diff --git a/.gitignore b/.gitignore
index 361b9c43c..8dbf46fa1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,8 +10,6 @@ coverage.lcov
 *.swp
 *.bak
 *.tgz
-packages/now-cli/.builders
-packages/now-cli/assets
 packages/now-cli/src/util/dev/templates/*.ts
 packages/now-cli/src/util/constants.ts
 packages/now-cli/test/**/yarn.lock
diff --git a/api/frameworks.ts b/api/frameworks.ts
index 683fa2c12..7f2b8da75 100644
--- a/api/frameworks.ts
+++ b/api/frameworks.ts
@@ -21,6 +21,9 @@ export default withApiHandler(async function(
 ) {
   res.setHeader('Access-Control-Allow-Origin', '*');
   res.setHeader('Access-Control-Allow-Methods', 'GET');
-  res.setHeader('Access-Control-Allow-Headers', 'Authorization, Accept, Content-Type');
+  res.setHeader(
+    'Access-Control-Allow-Headers',
+    'Authorization, Accept, Content-Type'
+  );
   return res.status(200).json(frameworks);
 });
diff --git a/packages/now-build-utils/src/types.ts b/packages/now-build-utils/src/types.ts
index 2edc685ef..368eba513 100644
--- a/packages/now-build-utils/src/types.ts
+++ b/packages/now-build-utils/src/types.ts
@@ -188,6 +188,34 @@ export interface ShouldServeOptions {
   config: Config;
 }
 
+export interface StartDevServerOptions {
+  /**
+   * Name of entrypoint file for this particular build job. Value
+   * `files[entrypoint]` is guaranteed to exist and be a valid File reference.
+   * `entrypoint` is always a discrete file and never a glob, since globs are
+   * expanded into separate builds at deployment time.
+   */
+  entrypoint: string;
+
+  /**
+   * A writable temporary directory where you are encouraged to perform your
+   * build process. This directory will be populated with the restored cache.
+   */
+  workPath: string;
+
+  /**
+   * An arbitrary object passed by the user in the build definition defined
+   * in `now.json`.
+   */
+  config: Config;
+
+  /**
+   * Runtime environment variables configuration from the project's `now.json`
+   * and local `.env` file.
+   */
+  env: Env;
+}
+
 export interface StartDevServerSuccess {
   /**
    * Port number where the dev server can be connected to, assumed to be running
@@ -213,7 +241,7 @@ export type StartDevServerResult = StartDevServerSuccess | null;
  * Source: https://gist.github.com/iainreid820/5c1cc527fe6b5b7dba41fec7fe54bf6e
  */
 // eslint-disable-next-line @typescript-eslint/no-namespace
-namespace PackageJson {
+export namespace PackageJson {
   /**
    * An author or contributor
    */
diff --git a/packages/now-cli/package.json b/packages/now-cli/package.json
index 02f068ae4..34bd44250 100644
--- a/packages/now-cli/package.json
+++ b/packages/now-cli/package.json
@@ -61,9 +61,19 @@
   "engines": {
     "node": ">= 10"
   },
+  "dependencies": {
+    "@vercel/build-utils": "2.3.1",
+    "@vercel/go": "1.1.1",
+    "@vercel/next": "2.6.1",
+    "@vercel/node": "1.6.1",
+    "@vercel/python": "1.2.1",
+    "@vercel/ruby": "1.2.1",
+    "@vercel/static-build": "0.17.1"
+  },
   "devDependencies": {
     "@sentry/node": "5.5.0",
     "@sindresorhus/slugify": "0.11.0",
+    "@tootallnate/once": "1.1.2",
     "@types/ansi-escapes": "3.0.0",
     "@types/ansi-regex": "4.0.0",
     "@types/async-retry": "1.2.1",
@@ -179,7 +189,6 @@
     "which": "2.0.2",
     "which-promise": "1.0.0",
     "write-json-file": "2.2.0",
-    "xdg-app-paths": "5.1.0",
-    "yarn": "1.22.0"
+    "xdg-app-paths": "5.1.0"
   }
 }
diff --git a/packages/now-cli/scripts/build.ts b/packages/now-cli/scripts/build.ts
index 6568e0c77..aeab8aad4 100644
--- a/packages/now-cli/scripts/build.ts
+++ b/packages/now-cli/scripts/build.ts
@@ -1,58 +1,10 @@
 import cpy from 'cpy';
-import tar from 'tar-fs';
 import execa from 'execa';
 import { join } from 'path';
-import pipe from 'promisepipe';
-import { createGzip } from 'zlib';
-import {
-  createWriteStream,
-  mkdirp,
-  remove,
-  writeJSON,
-  writeFile,
-} from 'fs-extra';
-
-import { getDistTag } from '../src/util/get-dist-tag';
-import pkg from '../package.json';
-import { getBundledBuilders } from '../src/util/dev/get-bundled-builders';
+import { remove, writeFile } from 'fs-extra';
 
 const dirRoot = join(__dirname, '..');
 
-async function createBuildersTarball() {
-  const distTag = getDistTag(pkg.version);
-  const builders = Array.from(getBundledBuilders()).map(b => `${b}@${distTag}`);
-  console.log(`Creating builders tarball with: ${builders.join(', ')}`);
-
-  const buildersDir = join(dirRoot, '.builders');
-  const assetsDir = join(dirRoot, 'assets');
-  await mkdirp(buildersDir);
-  await mkdirp(assetsDir);
-
-  const buildersTarballPath = join(assetsDir, 'builders.tar.gz');
-
-  try {
-    const buildersPkg = join(buildersDir, 'package.json');
-    await writeJSON(buildersPkg, { private: true }, { flag: 'wx' });
-  } catch (err) {
-    if (err.code !== 'EEXIST') {
-      throw err;
-    }
-  }
-
-  const yarn = join(dirRoot, '../../node_modules/yarn/bin/yarn.js');
-  await execa(process.execPath, [yarn, 'add', '--no-lockfile', ...builders], {
-    cwd: buildersDir,
-    stdio: 'inherit',
-  });
-
-  const packer = tar.pack(buildersDir);
-  await pipe(
-    packer,
-    createGzip(),
-    createWriteStream(buildersTarballPath)
-  );
-}
-
 async function createConstants() {
   console.log('Creating constants.ts');
   const filename = join(dirRoot, 'src/util/constants.ts');
@@ -81,10 +33,6 @@ async function main() {
     // During local development, these secrets will be empty.
     await createConstants();
 
-    // Create a tarball from all the `@now` scoped builders which will be bundled
-    // with Now CLI
-    await createBuildersTarball();
-
     // `now dev` uses chokidar to watch the filesystem, but opts-out of the
     // `fsevents` feature using `useFsEvents: false`, so delete the module here so
     // that it is not compiled by ncc, which makes the npm package size larger
diff --git a/packages/now-cli/src/commands/dev/dev.ts b/packages/now-cli/src/commands/dev/dev.ts
index d29ea1194..26d91fde3 100644
--- a/packages/now-cli/src/commands/dev/dev.ts
+++ b/packages/now-cli/src/commands/dev/dev.ts
@@ -84,6 +84,7 @@ export default async function dev(
   });
 
   process.once('SIGINT', () => devServer.stop());
+  process.once('SIGTERM', () => devServer.stop());
 
   await devServer.start(...listen);
 }
diff --git a/packages/now-cli/src/util/dev/builder-cache.ts b/packages/now-cli/src/util/dev/builder-cache.ts
index 17a7094e3..6bb9996a5 100644
--- a/packages/now-cli/src/util/dev/builder-cache.ts
+++ b/packages/now-cli/src/util/dev/builder-cache.ts
@@ -1,23 +1,13 @@
 import execa from 'execa';
 import semver from 'semver';
-import pipe from 'promisepipe';
 import retry from 'async-retry';
 import npa from 'npm-package-arg';
 import pluralize from 'pluralize';
-import { extract } from 'tar-fs';
-import { createHash } from 'crypto';
-import { createGunzip } from 'zlib';
-import { join } from 'path';
+import { basename, join } from 'path';
+import { PackageJson } from '@vercel/build-utils';
 import XDGAppPaths from 'xdg-app-paths';
-import { PackageJson, isStaticRuntime } from '@vercel/build-utils';
-import {
-  createReadStream,
-  mkdirp,
-  readFile,
-  readJSON,
-  writeFile,
-} from 'fs-extra';
-import pkg from '../../../package.json';
+import { mkdirp, readJSON, writeJSON } from 'fs-extra';
+import nowCliPkg from '../pkg';
 
 import { NoBuilderCacheError } from '../errors-ts';
 import { Output } from '../output';
@@ -34,6 +24,7 @@ const registryTypes = new Set(['version', 'tag', 'range']);
 const createStaticBuilder = (scope: string): BuilderWithPackage => {
   return {
     runInProcess: true,
+    requirePath: `${scope}/static`,
     builder: Object.freeze(staticBuilder),
     package: Object.freeze({ name: `@${scope}/static`, version: '' }),
   };
@@ -44,36 +35,10 @@ const localBuilders: { [key: string]: BuilderWithPackage } = {
   '@vercel/static': createStaticBuilder('vercel'),
 };
 
-const distTag = getDistTag(pkg.version);
+const distTag = nowCliPkg.version ? getDistTag(nowCliPkg.version) : 'canary';
 
 export const cacheDirPromise = prepareCacheDir();
 export const builderDirPromise = prepareBuilderDir();
-export const builderModulePathPromise = prepareBuilderModulePath();
-
-function readFileOrNull(
-  filePath: string,
-  encoding?: null
-): Promise<Buffer | null>;
-function readFileOrNull(
-  filePath: string,
-  encoding: string
-): Promise<string | null>;
-async function readFileOrNull(
-  filePath: string,
-  encoding?: string | null
-): Promise<Buffer | string | null> {
-  try {
-    if (encoding) {
-      return await readFile(filePath, encoding);
-    }
-    return await readFile(filePath);
-  } catch (err) {
-    if (err.code === 'ENOENT') {
-      return null;
-    }
-    throw err;
-  }
-}
 
 /**
  * Prepare cache directory for installing now-builders
@@ -94,51 +59,19 @@ export async function prepareBuilderDir() {
   const builderDir = join(await cacheDirPromise, 'builders');
   await mkdirp(builderDir);
 
-  // Extract the bundled `builders.tar.gz` file, if necessary
-  const bundledTarballPath = join(__dirname, '../../../assets/builders.tar.gz');
-
-  const existingPackageJson =
-    (await readFileOrNull(join(builderDir, 'package.json'), 'utf8')) || '{}';
-  const { dependencies = {} } = JSON.parse(existingPackageJson);
-
-  if (!hasBundledBuilders(dependencies)) {
-    const extractor = extract(builderDir);
-    await pipe(
-      createReadStream(bundledTarballPath),
-      createGunzip(),
-      extractor
-    );
+  // Create an empty `package.json` file, only if one does not already exist
+  try {
+    const buildersPkg = join(builderDir, 'package.json');
+    await writeJSON(buildersPkg, { private: true }, { flag: 'wx' });
+  } catch (err) {
+    if (err.code !== 'EEXIST') {
+      throw err;
+    }
   }
 
   return builderDir;
 }
 
-export async function prepareBuilderModulePath() {
-  const [builderDir, builderContents] = await Promise.all([
-    builderDirPromise,
-    readFile(join(__dirname, 'builder-worker.js')),
-  ]);
-  let needsWrite = false;
-  const builderSha = getSha(builderContents);
-  const cachedBuilderPath = join(builderDir, 'builder.js');
-
-  const cachedBuilderContents = await readFileOrNull(cachedBuilderPath);
-  if (cachedBuilderContents) {
-    const cachedBuilderSha = getSha(cachedBuilderContents);
-    if (builderSha !== cachedBuilderSha) {
-      needsWrite = true;
-    }
-  } else {
-    needsWrite = true;
-  }
-
-  if (needsWrite) {
-    await writeFile(cachedBuilderPath, builderContents);
-  }
-
-  return cachedBuilderPath;
-}
-
 function getNpmVersion(use = ''): string {
   const parsed = npa(use);
   if (registryTypes.has(parsed.type)) {
@@ -168,12 +101,20 @@ function parseVersionSafe(rawSpec: string) {
 export function filterPackage(
   builderSpec: string,
   distTag: string,
-  buildersPkg: PackageJson
+  buildersPkg: PackageJson,
+  nowCliPkg: PackageJson
 ) {
   if (builderSpec in localBuilders) return false;
   const parsed = npa(builderSpec);
   const parsedVersion = parseVersionSafe(parsed.rawSpec);
-  // skip install of already installed Runtime
+
+  // If it's a builder that is part of Now CLI's `dependencies` then
+  // the builder is already installed into `node_modules`
+  if (isBundledBuilder(parsed, nowCliPkg)) {
+    return false;
+  }
+
+  // Skip install of already installed Runtime
   if (
     parsed.name &&
     parsed.type === 'version' &&
@@ -215,7 +156,6 @@ export function filterPackage(
  */
 export async function installBuilders(
   packagesSet: Set<string>,
-  yarnDir: string,
   output: Output,
   builderDir?: string
 ): Promise<void> {
@@ -231,9 +171,12 @@ export async function installBuilders(
   if (!builderDir) {
     builderDir = await builderDirPromise;
   }
-  const yarnPath = join(yarnDir, 'yarn');
   const buildersPkgPath = join(builderDir, 'package.json');
   const buildersPkgBefore = await readJSON(buildersPkgPath);
+  const depsBefore = {
+    ...buildersPkgBefore.devDependencies,
+    ...buildersPkgBefore.dependencies,
+  };
 
   packages.push(
     getBuildUtils(packages, 'vercel'),
@@ -242,7 +185,7 @@ export async function installBuilders(
 
   // Filter out any packages that come packaged with `now-cli`
   const packagesToInstall = packages.filter(p =>
-    filterPackage(p, distTag, buildersPkgBefore)
+    filterPackage(p, distTag, buildersPkgBefore, nowCliPkg)
   );
 
   if (packagesToInstall.length === 0) {
@@ -261,14 +204,11 @@ export async function installBuilders(
     await retry(
       () =>
         execa(
-          process.execPath,
+          'npm',
           [
-            yarnPath,
-            'add',
-            '--exact',
-            '--no-lockfile',
-            '--non-interactive',
-            '--ignore-workspace-root-check',
+            'install',
+            '--save-exact',
+            '--no-package-lock',
             ...packagesToInstall,
           ],
           {
@@ -283,8 +223,12 @@ export async function installBuilders(
 
   const updatedPackages: string[] = [];
   const buildersPkgAfter = await readJSON(buildersPkgPath);
-  for (const [name, version] of Object.entries(buildersPkgAfter.dependencies)) {
-    if (version !== buildersPkgBefore.dependencies[name]) {
+  const depsAfter = {
+    ...buildersPkgAfter.devDependencies,
+    ...buildersPkgAfter.dependencies,
+  };
+  for (const [name, version] of Object.entries(depsAfter)) {
+    if (version !== depsBefore[name]) {
       output.debug(`Runtime "${name}" updated to version \`${version}\``);
       updatedPackages.push(name);
     }
@@ -295,7 +239,6 @@ export async function installBuilders(
 
 export async function updateBuilders(
   packagesSet: Set<string>,
-  yarnDir: string,
   output: Output,
   builderDir?: string
 ): Promise<string[]> {
@@ -303,46 +246,59 @@ export async function updateBuilders(
     builderDir = await builderDirPromise;
   }
 
+  const updatedPackages: string[] = [];
   const packages = Array.from(packagesSet);
-  const yarnPath = join(yarnDir, 'yarn');
   const buildersPkgPath = join(builderDir, 'package.json');
   const buildersPkgBefore = await readJSON(buildersPkgPath);
+  const depsBefore = {
+    ...buildersPkgBefore.devDependencies,
+    ...buildersPkgBefore.dependencies,
+  };
 
-  packages.push(
-    getBuildUtils(packages, 'vercel'),
-    getBuildUtils(packages, 'now')
-  );
+  const packagesToUpdate = packages.filter(p => {
+    if (p in localBuilders) return false;
 
-  await retry(
-    () =>
-      execa(
-        process.execPath,
-        [
-          yarnPath,
-          'add',
-          '--exact',
-          '--no-lockfile',
-          '--non-interactive',
-          '--ignore-workspace-root-check',
-          ...packages.filter(p => !isStaticRuntime(p)),
-        ],
-        {
-          cwd: builderDir,
-        }
-      ),
-    { retries: 2 }
-  );
-
-  const updatedPackages: string[] = [];
-  const buildersPkgAfter = await readJSON(buildersPkgPath);
-  for (const [name, version] of Object.entries(buildersPkgAfter.dependencies)) {
-    if (version !== buildersPkgBefore.dependencies[name]) {
-      output.debug(`Runtime "${name}" updated to version \`${version}\``);
-      updatedPackages.push(name);
+    // If it's a builder that is part of Now CLI's `dependencies` then
+    // don't update it
+    if (isBundledBuilder(npa(p), nowCliPkg)) {
+      return false;
     }
-  }
 
-  purgeRequireCache(updatedPackages, builderDir, output);
+    return true;
+  });
+
+  if (packagesToUpdate.length > 0) {
+    packages.push(
+      getBuildUtils(packages, 'vercel'),
+      getBuildUtils(packages, 'now')
+    );
+
+    await retry(
+      () =>
+        execa(
+          'npm',
+          ['install', '--save-exact', '--no-package-lock', ...packagesToUpdate],
+          {
+            cwd: builderDir,
+          }
+        ),
+      { retries: 2 }
+    );
+
+    const buildersPkgAfter = await readJSON(buildersPkgPath);
+    const depsAfter = {
+      ...buildersPkgAfter.devDependencies,
+      ...buildersPkgAfter.dependencies,
+    };
+    for (const [name, version] of Object.entries(depsAfter)) {
+      if (version !== depsBefore[name]) {
+        output.debug(`Runtime "${name}" updated to version \`${version}\``);
+        updatedPackages.push(name);
+      }
+    }
+
+    purgeRequireCache(updatedPackages, builderDir, output);
+  }
 
   return updatedPackages;
 }
@@ -352,7 +308,6 @@ export async function updateBuilders(
  */
 export async function getBuilder(
   builderPkg: string,
-  yarnDir: string,
   output: Output,
   builderDir?: string,
   isRetry = false
@@ -362,34 +317,74 @@ export async function getBuilder(
     if (!builderDir) {
       builderDir = await builderDirPromise;
     }
+    let requirePath: string;
     const parsed = npa(builderPkg);
-    const buildersPkg = await readJSON(join(builderDir, 'package.json'));
-    const pkgName = getPackageName(parsed, buildersPkg) || builderPkg;
-    const dest = join(builderDir, 'node_modules', pkgName);
+
+    // First check if it's a bundled Runtime in Now CLI's `node_modules`
+    const bundledBuilder = isBundledBuilder(parsed, nowCliPkg);
+    if (bundledBuilder && parsed.name) {
+      requirePath = parsed.name;
+    } else {
+      const buildersPkg = await readJSON(join(builderDir, 'package.json'));
+      const pkgName = getPackageName(parsed, buildersPkg) || builderPkg;
+      requirePath = join(builderDir, 'node_modules', pkgName);
+    }
+
     try {
-      const mod = require(dest);
-      const pkg = require(join(dest, 'package.json'));
+      output.debug(`Requiring runtime: "${requirePath}"`);
+      const mod = require(requirePath);
+      const pkg = require(join(requirePath, 'package.json'));
       builderWithPkg = {
+        requirePath,
         builder: Object.freeze(mod),
         package: Object.freeze(pkg),
       };
     } catch (err) {
       if (err.code === 'MODULE_NOT_FOUND' && !isRetry) {
         output.debug(
-          `Attempted to require ${builderPkg}, but it is not installed`
+          `Attempted to require ${requirePath}, but it is not installed`
         );
         const pkgSet = new Set([builderPkg]);
-        await installBuilders(pkgSet, yarnDir, output, builderDir);
+        await installBuilders(pkgSet, output, builderDir);
 
         // Run `getBuilder()` again now that the builder has been installed
-        return getBuilder(builderPkg, yarnDir, output, builderDir, true);
+        return getBuilder(builderPkg, output, builderDir, true);
       }
       throw err;
     }
+
+    // If it's a bundled builder, then cache the require call
+    if (bundledBuilder) {
+      localBuilders[builderPkg] = builderWithPkg;
+    }
   }
   return builderWithPkg;
 }
 
+export function isBundledBuilder(
+  parsed: npa.Result,
+  pkg: PackageJson
+): boolean {
+  if (!parsed.name || !pkg.dependencies) {
+    return false;
+  }
+
+  const bundledVersion = pkg.dependencies[parsed.name];
+  if (bundledVersion) {
+    if (parsed.type === 'tag') {
+      if (parsed.fetchSpec === 'canary') {
+        return bundledVersion.includes('canary');
+      } else if (parsed.fetchSpec === 'latest') {
+        return !bundledVersion.includes('canary');
+      }
+    } else if (parsed.type === 'version') {
+      return parsed.fetchSpec === bundledVersion;
+    }
+  }
+
+  return false;
+}
+
 function getPackageName(
   parsed: npa.Result,
   buildersPkg: PackageJson
@@ -397,30 +392,18 @@ function getPackageName(
   if (registryTypes.has(parsed.type)) {
     return parsed.name;
   }
-  const deps = { ...buildersPkg.devDependencies, ...buildersPkg.dependencies };
+  const deps: { [name: string]: string } = {
+    ...buildersPkg.devDependencies,
+    ...buildersPkg.dependencies,
+  };
   for (const [name, dep] of Object.entries(deps)) {
-    if (dep === parsed.raw) {
+    if (dep === parsed.raw || basename(dep) === basename(parsed.raw)) {
       return name;
     }
   }
   return null;
 }
 
-function getSha(buffer: Buffer): string {
-  const hash = createHash('sha256');
-  hash.update(buffer);
-  return hash.digest('hex');
-}
-
-function hasBundledBuilders(dependencies: { [name: string]: string }): boolean {
-  for (const name of getBundledBuilders()) {
-    if (!(name in dependencies)) {
-      return false;
-    }
-  }
-  return true;
-}
-
 function purgeRequireCache(
   packages: string[],
   builderDir: string,
diff --git a/packages/now-cli/src/util/dev/builder-worker.js b/packages/now-cli/src/util/dev/builder-worker.js
index 664ee6466..a6ffdb38d 100644
--- a/packages/now-cli/src/util/dev/builder-worker.js
+++ b/packages/now-cli/src/util/dev/builder-worker.js
@@ -1,10 +1,10 @@
 /**
- * This file gets copied out of the `pkg` snapshot filesystem into the `now dev`
+ * This file gets copied out of the `pkg` snapshot filesystem into the `vc dev`
  * builder cache directory, so it's very important that it does not rely on any
  * modules from npm that would not be available in that directory (so basically,
- * only Now builders and `@now/build-utils`.
+ * only Vercel Runtimes and `@vercel/build-utils`.
  */
-const { FileFsRef } = require('@now/build-utils');
+const { FileFsRef } = require('@vercel/build-utils');
 
 process.on('unhandledRejection', err => {
   console.error('Exiting builder due to build error:');
@@ -24,21 +24,21 @@ function onMessage(message) {
 }
 
 async function processMessage(message) {
-  const { builderName, buildParams } = message;
-  const builder = require(builderName);
+  const { requirePath, buildOptions } = message;
+  const builder = require(requirePath);
 
   // Convert the `files` to back into `FileFsRef` instances
-  for (const name of Object.keys(buildParams.files)) {
+  for (const name of Object.keys(buildOptions.files)) {
     const ref = Object.assign(
       Object.create(FileFsRef.prototype),
-      buildParams.files[name]
+      buildOptions.files[name]
     );
-    buildParams.files[name] = ref;
+    buildOptions.files[name] = ref;
   }
 
-  const result = await builder.build(buildParams);
+  const result = await builder.build(buildOptions);
 
-  // `@now/next` sets this, but it causes "Converting circular
+  // `@vercel/next` sets this, but it causes "Converting circular
   // structure to JSON" errors, so delete the property...
   delete result.childProcesses;
 
diff --git a/packages/now-cli/src/util/dev/builder.ts b/packages/now-cli/src/util/dev/builder.ts
index 98ebb41d3..c31bdbe9d 100644
--- a/packages/now-cli/src/util/dev/builder.ts
+++ b/packages/now-cli/src/util/dev/builder.ts
@@ -2,12 +2,13 @@
 /* eslint-disable @typescript-eslint/no-non-null-assertion */
 import ms from 'ms';
 import bytes from 'bytes';
-import { promisify } from 'util';
 import { delimiter, dirname, join } from 'path';
 import { fork, ChildProcess } from 'child_process';
 import { createFunction } from '@zeit/fun';
 import {
   Builder,
+  BuildOptions,
+  Env,
   File,
   Lambda,
   FileBlob,
@@ -16,17 +17,16 @@ import {
 } from '@vercel/build-utils';
 import plural from 'pluralize';
 import minimatch from 'minimatch';
-import _treeKill from 'tree-kill';
 
 import { Output } from '../output';
 import highlight from '../output/highlight';
+import { treeKill } from '../tree-kill';
 import { relative } from '../path-helpers';
 import { LambdaSizeExceededError } from '../errors-ts';
 
 import DevServer from './server';
-import { builderModulePathPromise, getBuilder } from './builder-cache';
+import { getBuilder } from './builder-cache';
 import {
-  EnvConfig,
   NowConfig,
   BuildMatch,
   BuildResult,
@@ -34,7 +34,6 @@ import {
   BuilderOutput,
   BuildResultV3,
   BuilderOutputs,
-  BuilderParams,
   EnvConfigs,
 } from './types';
 import { normalizeRoutes } from '@vercel/routing-utils';
@@ -51,27 +50,18 @@ interface BuildMessageResult extends BuildMessage {
   error?: object;
 }
 
-const treeKill = promisify(_treeKill);
-
 async function createBuildProcess(
   match: BuildMatch,
   envConfigs: EnvConfigs,
   workPath: string,
-  output: Output,
-  yarnPath?: string
+  output: Output
 ): Promise<ChildProcess> {
-  const { execPath } = process;
-  const modulePath = await builderModulePathPromise;
+  const builderWorkerPath = join(__dirname, 'builder-worker.js');
 
   // Ensure that `node` is in the builder's `PATH`
-  let PATH = `${dirname(execPath)}${delimiter}${process.env.PATH}`;
+  let PATH = `${dirname(process.execPath)}${delimiter}${process.env.PATH}`;
 
-  // Ensure that `yarn` is in the builder's `PATH`
-  if (yarnPath) {
-    PATH = `${yarnPath}${delimiter}${PATH}`;
-  }
-
-  const env: EnvConfig = {
+  const env: Env = {
     ...process.env,
     PATH,
     ...envConfigs.allEnv,
@@ -79,11 +69,9 @@ async function createBuildProcess(
     VERCEL_REGION: 'dev1',
   };
 
-  const buildProcess = fork(modulePath, [], {
+  const buildProcess = fork(builderWorkerPath, [], {
     cwd: workPath,
     env,
-    execPath,
-    execArgv: [],
   });
   match.buildProcess = buildProcess;
 
@@ -117,10 +105,10 @@ export async function executeBuild(
   filesRemoved?: string[]
 ): Promise<void> {
   const {
-    builderWithPkg: { runInProcess, builder, package: pkg },
+    builderWithPkg: { runInProcess, requirePath, builder, package: pkg },
   } = match;
   const { entrypoint } = match;
-  const { debug, envConfigs, yarnPath, cwd: workPath } = devServer;
+  const { debug, envConfigs, cwd: workPath } = devServer;
 
   const startTime = Date.now();
   const showBuildTimestamp =
@@ -144,15 +132,14 @@ export async function executeBuild(
       match,
       envConfigs,
       workPath,
-      devServer.output,
-      yarnPath
+      devServer.output
     );
   }
 
   const vercelDir = getVercelDirectory(workPath);
   const devCacheDir = join(vercelDir, 'cache');
 
-  const buildParams: BuilderParams = {
+  const buildOptions: BuildOptions = {
     files,
     entrypoint,
     workPath,
@@ -174,8 +161,8 @@ export async function executeBuild(
   if (buildProcess) {
     buildProcess.send({
       type: 'build',
-      builderName: pkg.name,
-      buildParams,
+      requirePath,
+      buildOptions,
     });
 
     buildResultOrOutputs = await new Promise((resolve, reject) => {
@@ -206,7 +193,7 @@ export async function executeBuild(
       buildProcess!.on('message', onMessage);
     });
   } else {
-    buildResultOrOutputs = await builder.build(buildParams);
+    buildResultOrOutputs = await builder.build(buildOptions);
   }
 
   // Sort out build result to builder v2 shape
@@ -404,7 +391,6 @@ export async function executeBuild(
 export async function getBuildMatches(
   nowConfig: NowConfig,
   cwd: string,
-  yarnDir: string,
   output: Output,
   devServer: DevServer,
   fileList: string[]
@@ -456,7 +442,7 @@ export async function getBuildMatches(
 
     for (const file of files) {
       src = relative(cwd, file);
-      const builderWithPkg = await getBuilder(use, yarnDir, output);
+      const builderWithPkg = await getBuilder(use, output);
       matches.push({
         ...buildConfig,
         src,
diff --git a/packages/now-cli/src/util/dev/router.ts b/packages/now-cli/src/util/dev/router.ts
index 69900ccc4..759da2fcc 100644
--- a/packages/now-cli/src/util/dev/router.ts
+++ b/packages/now-cli/src/util/dev/router.ts
@@ -4,7 +4,7 @@ import PCRE from 'pcre-to-regexp';
 import isURL from './is-url';
 import DevServer from './server';
 
-import { HttpHeadersConfig, RouteConfig, RouteResult } from './types';
+import { HttpHeadersConfig, RouteResult } from './types';
 import { isHandler, Route, HandleValue } from '@vercel/routing-utils';
 
 export function resolveRouteParameters(
@@ -48,10 +48,10 @@ export function getRoutesTypes(routes: Route[] = []) {
 export async function devRouter(
   reqUrl: string = '/',
   reqMethod?: string,
-  routes?: RouteConfig[],
+  routes?: Route[],
   devServer?: DevServer,
   previousHeaders?: HttpHeadersConfig,
-  missRoutes?: RouteConfig[],
+  missRoutes?: Route[],
   phase?: HandleValue | null
 ): Promise<RouteResult> {
   let result: RouteResult | undefined;
diff --git a/packages/now-cli/src/util/dev/server.ts b/packages/now-cli/src/util/dev/server.ts
index e7e6bfc95..d256b70cf 100644
--- a/packages/now-cli/src/util/dev/server.ts
+++ b/packages/now-cli/src/util/dev/server.ts
@@ -12,6 +12,7 @@ import serveHandler from 'serve-handler';
 import { watch, FSWatcher } from 'chokidar';
 import { parse as parseDotenv } from 'dotenv';
 import { basename, dirname, extname, join } from 'path';
+import once from '@tootallnate/once';
 import directoryTemplate from 'serve-handler/src/directory';
 import getPort from 'get-port';
 import { ChildProcess } from 'child_process';
@@ -23,9 +24,12 @@ import {
   getTransformedRoutes,
   appendRoutesToPhase,
   HandleValue,
+  Route,
 } from '@vercel/routing-utils';
 import {
   Builder,
+  Env,
+  StartDevServerResult,
   FileFsRef,
   PackageJson,
   detectBuilders,
@@ -35,7 +39,6 @@ import {
   isOfficialRuntime,
 } from '@vercel/build-utils';
 
-import { once } from '../once';
 import link from '../output/link';
 import { Output } from '../output';
 import { relative } from '../path-helpers';
@@ -57,10 +60,13 @@ import {
 
 import { devRouter, getRoutesTypes } from './router';
 import getMimeType from './mime-type';
-import { getYarnPath } from './yarn-installer';
 import { executeBuild, getBuildMatches, shutdownBuilder } from './builder';
 import { generateErrorMessage, generateHttpStatusDescription } from './errors';
-import { installBuilders, updateBuilders } from './builder-cache';
+import {
+  installBuilders,
+  updateBuilders,
+  builderDirPromise,
+} from './builder-cache';
 
 // HTML templates
 import errorTemplate from './templates/error';
@@ -70,7 +76,6 @@ import errorTemplate502 from './templates/error_502';
 import redirectTemplate from './templates/redirect';
 
 import {
-  EnvConfig,
   NowConfig,
   DevServerOptions,
   BuildMatch,
@@ -81,7 +86,6 @@ import {
   InvokePayload,
   InvokeResult,
   ListenSpec,
-  RouteConfig,
   RouteResult,
   HttpHeadersConfig,
   EnvConfigs,
@@ -111,7 +115,6 @@ export default class DevServer {
   public envConfigs: EnvConfigs;
   public frameworkSlug: string | null;
   public files: BuilderInputs;
-  public yarnPath: string;
   public address: string;
 
   private cachedNowConfig: NowConfig | null;
@@ -131,6 +134,7 @@ export default class DevServer {
   private devCommand?: string;
   private devProcess?: ChildProcess;
   private devProcessPort?: number;
+  private devServerPids: Set<number>;
 
   private getNowConfigPromise: Promise<NowConfig> | null;
   private blockingBuildsPromise: Promise<void> | null;
@@ -145,14 +149,10 @@ export default class DevServer {
     this.address = '';
     this.devCommand = options.devCommand;
     this.frameworkSlug = options.frameworkSlug;
-
-    // This gets updated when `start()` is invoked
-    this.yarnPath = '/';
-
     this.cachedNowConfig = null;
     this.caseSensitive = false;
     this.apiDir = null;
-    this.apiExtensions = new Set<string>();
+    this.apiExtensions = new Set();
     this.server = http.createServer(this.devServerHandler);
     this.server.timeout = 0; // Disable timeout
     this.stopping = false;
@@ -171,6 +171,8 @@ export default class DevServer {
     this.podId = Math.random()
       .toString(32)
       .slice(-5);
+
+    this.devServerPids = new Set();
   }
 
   async exit(code = 1) {
@@ -357,7 +359,6 @@ export default class DevServer {
     const matches = await getBuildMatches(
       nowConfig,
       this.cwd,
-      this.yarnPath,
       this.output,
       this,
       fileList
@@ -449,11 +450,11 @@ export default class DevServer {
     await this.updateBuildMatches(nowConfig);
   }
 
-  async getLocalEnv(fileName: string, base?: EnvConfig): Promise<EnvConfig> {
+  async getLocalEnv(fileName: string, base?: Env): Promise<Env> {
     // TODO: use the file watcher to only invalidate the env `dotfile`
     // once a change to the `fileName` occurs
     const filePath = join(this.cwd, fileName);
-    let env: EnvConfig = {};
+    let env: Env = {};
     try {
       const dotenv = await fs.readFile(filePath, 'utf8');
       this.output.debug(`Using local env: ${filePath}`);
@@ -583,7 +584,7 @@ export default class DevServer {
         config.builds = config.builds || [];
         config.builds.push(...builders);
 
-        const routes: RouteConfig[] = [];
+        const routes: Route[] = [];
         const { routes: nowConfigRoutes } = config;
         routes.push(...(redirectRoutes || []));
         routes.push(
@@ -656,6 +657,7 @@ export default class DevServer {
     if (config.version === 1) {
       this.output.error('Only `version: 2` is supported by `now dev`');
       await this.exit(1);
+      return;
     }
 
     await this.tryValidateOrExit(config, validateNowConfigBuilds);
@@ -668,13 +670,8 @@ export default class DevServer {
     await this.tryValidateOrExit(config, validateNowConfigFunctions);
   }
 
-  validateEnvConfig(
-    type: string,
-    env: EnvConfig = {},
-    localEnv: EnvConfig = {}
-  ): EnvConfig {
+  validateEnvConfig(type: string, env: Env = {}, localEnv: Env = {}): Env {
     // Validate if there are any missing env vars defined in `vercel.json`,
-
     // but not in the `.env` / `.build.env` file
     const missing: string[] = Object.entries(env)
       .filter(
@@ -689,7 +686,7 @@ export default class DevServer {
       throw new MissingDotenvVarsError(type, missing);
     }
 
-    const merged: EnvConfig = { ...env, ...localEnv };
+    const merged: Env = { ...env, ...localEnv };
 
     // Validate that the env var name matches what AWS Lambda allows:
     //   - https://docs.aws.amazon.com/lambda/latest/dg/env_variables.html
@@ -737,7 +734,6 @@ export default class DevServer {
     }
 
     const { ig } = await getVercelIgnore(this.cwd);
-    this.yarnPath = await getYarnPath(this.output);
     this.filter = ig.createFilter();
 
     // Retrieve the path of the native module
@@ -770,16 +766,12 @@ export default class DevServer {
         .map((b: Builder) => b.use)
     );
 
-    await installBuilders(builders, this.yarnPath, this.output);
+    await installBuilders(builders, this.output);
     await this.updateBuildMatches(nowConfig, true);
 
     // Updating builders happens lazily, and any builders that were updated
     // get their "build matches" invalidated so that the new version is used.
-    this.updateBuildersPromise = updateBuilders(
-      builders,
-      this.yarnPath,
-      this.output
-    )
+    this.updateBuildersPromise = updateBuilders(builders, this.output)
       .then(updatedBuilders => {
         this.updateBuildersPromise = null;
         this.invalidateBuildMatches(nowConfig, updatedBuilders);
@@ -875,6 +867,7 @@ export default class DevServer {
    */
   async stop(exitCode?: number): Promise<void> {
     const { devProcess } = this;
+    const { debug } = this.output;
     if (this.stopping) return;
 
     this.stopping = true;
@@ -905,15 +898,22 @@ export default class DevServer {
     ops.push(close(this.server));
 
     if (this.watcher) {
-      this.output.debug(`Closing file watcher`);
+      debug(`Closing file watcher`);
       this.watcher.close();
     }
 
     if (this.updateBuildersPromise) {
-      this.output.debug(`Waiting for builders update to complete`);
+      debug(`Waiting for builders update to complete`);
       ops.push(this.updateBuildersPromise);
     }
 
+    for (const pid of this.devServerPids) {
+      ops.push(this.killBuilderDevServer(pid));
+    }
+
+    // Ensure that the builders module cache is created
+    ops.push(builderDirPromise);
+
     try {
       await Promise.all(ops);
     } catch (err) {
@@ -929,6 +929,18 @@ export default class DevServer {
     }
   }
 
+  async killBuilderDevServer(pid: number) {
+    const { debug } = this.output;
+    debug(`Killing builder dev server with PID ${pid}`);
+    this.devServerPids.delete(pid);
+    try {
+      process.kill(pid, 'SIGTERM');
+      debug(`Killed builder dev server with PID ${pid}`);
+    } catch (err) {
+      debug(`Failed to kill builder dev server with PID ${pid}: ${err}`);
+    }
+  }
+
   async send404(
     req: http.IncomingMessage,
     res: http.ServerResponse,
@@ -1222,9 +1234,11 @@ export default class DevServer {
     res: http.ServerResponse,
     nowRequestId: string,
     nowConfig: NowConfig,
-    routes: RouteConfig[] | undefined = nowConfig.routes,
+    routes: Route[] | undefined = nowConfig.routes,
     callLevel: number = 0
   ) => {
+    const { debug } = this.output;
+
     // If there is a double-slash present in the URL,
     // then perform a redirect to make it "clean".
     const parsed = url.parse(req.url || '/');
@@ -1241,16 +1255,16 @@ export default class DevServer {
         return;
       }
 
-      this.output.debug(`Rewriting URL from "${req.url}" to "${location}"`);
+      debug(`Rewriting URL from "${req.url}" to "${location}"`);
       req.url = location;
     }
 
-    await this.updateBuildMatches(nowConfig);
+    if (callLevel === 0) {
+      await this.updateBuildMatches(nowConfig);
+    }
 
     if (this.blockingBuildsPromise) {
-      this.output.debug(
-        'Waiting for builds to complete before handling request'
-      );
+      debug('Waiting for builds to complete before handling request');
       await this.blockingBuildsPromise;
     }
 
@@ -1291,7 +1305,7 @@ export default class DevServer {
         Object.assign(destParsed.query, routeResult.uri_args);
         const destUrl = url.format(destParsed);
 
-        this.output.debug(`ProxyPass: ${destUrl}`);
+        debug(`ProxyPass: ${destUrl}`);
         this.setResponseHeaders(res, nowRequestId);
         return proxyPass(req, res, destUrl, this.output);
       }
@@ -1382,15 +1396,25 @@ export default class DevServer {
     });
 
     if (statusCode) {
-      res.statusCode = statusCode;
+      // Set the `statusCode` as read-only so that `http-proxy`
+      // is not able to modify the value in the future
+      Object.defineProperty(res, 'statusCode', {
+        get() {
+          return statusCode;
+        },
+        /* eslint-disable @typescript-eslint/no-unused-vars */
+        set(_: number) {
+          /* ignore */
+        },
+      });
     }
 
     const requestPath = dest.replace(/^\//, '');
 
     if (!match) {
-      // if the dev command is started, proxy to it
+      // If the dev command is started, then proxy to it
       if (this.devProcessPort) {
-        this.output.debug('Proxy to dev command server');
+        debug('Proxying to frontend dev server');
         this.setResponseHeaders(res, nowRequestId);
         return proxyPass(
           req,
@@ -1423,7 +1447,7 @@ export default class DevServer {
       origUrl.pathname = dest;
       Object.assign(origUrl.query, uri_args);
       const newUrl = url.format(origUrl);
-      this.output.debug(
+      debug(
         `Checking build result's ${buildResult.routes.length} \`routes\` to match ${newUrl}`
       );
       const matchedRoute = await devRouter(
@@ -1433,9 +1457,7 @@ export default class DevServer {
         this
       );
       if (matchedRoute.found && callLevel === 0) {
-        this.output.debug(
-          `Found matching route ${matchedRoute.dest} for ${newUrl}`
-        );
+        debug(`Found matching route ${matchedRoute.dest} for ${newUrl}`);
         req.url = newUrl;
         await this.serveProjectAsNowV2(
           req,
@@ -1449,7 +1471,76 @@ export default class DevServer {
       }
     }
 
+    // Before doing any asset matching, check if this builder supports the
+    // `startDevServer()` "optimization". In this case, the now dev server invokes
+    // `startDevServer()` on the builder for every HTTP request so that it boots
+    // up a single-serve dev HTTP server that now dev will proxy this HTTP request
+    // to. Once the proxied request is finished, now dev shuts down the dev
+    // server child process.
+    const { builder, package: builderPkg } = match.builderWithPkg;
+    if (typeof builder.startDevServer === 'function') {
+      let devServerResult: StartDevServerResult = null;
+      try {
+        devServerResult = await builder.startDevServer({
+          entrypoint: match.entrypoint,
+          workPath: this.cwd,
+          config: match.config || {},
+          env: this.envConfigs.runEnv || {},
+        });
+      } catch (err) {
+        // `startDevServer()` threw an error. Most likely this means the dev
+        // server process exited before sending the port information message
+        // (missing dependency at runtime, for example).
+        debug(`Error starting "${builderPkg.name}" dev server: ${err}`);
+        await this.sendError(
+          req,
+          res,
+          nowRequestId,
+          'NO_STATUS_CODE_FROM_DEV_SERVER',
+          502
+        );
+        return;
+      }
+
+      if (devServerResult) {
+        // When invoking lambda functions, the region where the lambda was invoked
+        // is also included in the request ID. So use the same `dev1` fake region.
+        nowRequestId = generateRequestId(this.podId, true);
+
+        const { port, pid } = devServerResult;
+        this.devServerPids.add(pid);
+
+        res.once('close', () => {
+          this.killBuilderDevServer(pid);
+        });
+
+        debug(
+          `Proxying to "${builderPkg.name}" dev server (port=${port}, pid=${pid})`
+        );
+
+        // Mix in the routing based query parameters
+        const parsed = url.parse(req.url || '/', true);
+        Object.assign(parsed.query, uri_args);
+        req.url = url.format({
+          pathname: parsed.pathname,
+          query: parsed.query,
+        });
+
+        this.setResponseHeaders(res, nowRequestId);
+        return proxyPass(
+          req,
+          res,
+          `http://localhost:${port}`,
+          this.output,
+          false
+        );
+      } else {
+        debug(`Skipping \`startDevServer()\` for ${match.entrypoint}`);
+      }
+    }
+
     let foundAsset = findAsset(match, requestPath, nowConfig);
+
     if (!foundAsset && callLevel === 0) {
       await this.triggerBuild(match, buildRequestPath, req);
 
@@ -1464,7 +1555,7 @@ export default class DevServer {
       this.devProcessPort &&
       (!foundAsset || (foundAsset && foundAsset.asset.type !== 'Lambda'))
     ) {
-      this.output.debug('Proxy to dev command server');
+      debug('Proxying to frontend dev server');
       this.setResponseHeaders(res, nowRequestId);
       return proxyPass(
         req,
@@ -1481,7 +1572,7 @@ export default class DevServer {
     }
 
     const { asset, assetKey } = foundAsset;
-    this.output.debug(
+    debug(
       `Serving asset: [${asset.type}] ${assetKey} ${(asset as any)
         .contentType || ''}`
     );
@@ -1550,7 +1641,7 @@ export default class DevServer {
           body: body.toString('base64'),
         };
 
-        this.output.debug(`Invoking lambda: "${assetKey}" with ${path}`);
+        debug(`Invoking lambda: "${assetKey}" with ${path}`);
 
         let result: InvokeResult;
         try {
@@ -1699,7 +1790,7 @@ export default class DevServer {
 
     const port = await getPort();
 
-    const env: EnvConfig = {
+    const env: Env = {
       // Because of child process 'pipe' below, isTTY will be false.
       // Most frameworks use `chalk`/`supports-color` so we enable it anyway.
       FORCE_COLOR: process.stdout.isTTY ? '1' : '0',
@@ -1912,7 +2003,7 @@ async function shouldServe(
     const shouldServe = await builder.shouldServe({
       entrypoint: src,
       files,
-      config,
+      config: config || {},
       requestPath,
       workPath: devServer.cwd,
     });
diff --git a/packages/now-cli/src/util/dev/static-builder.ts b/packages/now-cli/src/util/dev/static-builder.ts
index b98150af2..9431094f6 100644
--- a/packages/now-cli/src/util/dev/static-builder.ts
+++ b/packages/now-cli/src/util/dev/static-builder.ts
@@ -1,5 +1,10 @@
 import { basename, extname, join } from 'path';
-import { BuilderParams, BuildResult, ShouldServeParams } from './types';
+import {
+  FileFsRef,
+  BuildOptions,
+  ShouldServeOptions,
+} from '@vercel/build-utils';
+import { BuildResult } from './types';
 
 export const version = 2;
 
@@ -7,7 +12,7 @@ export function build({
   files,
   entrypoint,
   config,
-}: BuilderParams): BuildResult {
+}: BuildOptions): BuildResult {
   let path = entrypoint;
   const outputDir = config.zeroConfig ? config.outputDirectory : '';
   const outputMatch = outputDir + '/';
@@ -16,7 +21,7 @@ export function build({
     path = path.slice(outputMatch.length);
   }
   const output = {
-    [path]: files[entrypoint],
+    [path]: files[entrypoint] as FileFsRef,
   };
   const watch = [path];
 
@@ -28,7 +33,7 @@ export function shouldServe({
   files,
   requestPath,
   config = {},
-}: ShouldServeParams) {
+}: ShouldServeOptions) {
   let outputPrefix = '';
   const outputDir = config.zeroConfig ? config.outputDirectory : '';
   const outputMatch = outputDir + '/';
diff --git a/packages/now-cli/src/util/dev/types.ts b/packages/now-cli/src/util/dev/types.ts
index 3f1833aeb..2d3a8b07d 100644
--- a/packages/now-cli/src/util/dev/types.ts
+++ b/packages/now-cli/src/util/dev/types.ts
@@ -3,12 +3,16 @@ import { ChildProcess } from 'child_process';
 import { Lambda as FunLambda } from '@zeit/fun';
 import {
   Builder as BuildConfig,
+  BuildOptions,
+  PrepareCacheOptions,
+  ShouldServeOptions,
+  StartDevServerOptions,
+  StartDevServerResult,
+  Env,
   FileBlob,
   FileFsRef,
   Lambda,
   PackageJson,
-  Config,
-  Meta,
 } from '@vercel/build-utils';
 import { NowConfig } from '@vercel/client';
 import { HandleValue, Route } from '@vercel/routing-utils';
@@ -23,25 +27,21 @@ export interface DevServerOptions {
   frameworkSlug: string | null;
 }
 
-export interface EnvConfig {
-  [name: string]: string | undefined;
-}
-
 export interface EnvConfigs {
   /**
    * environment variables from `.env.build` file (deprecated)
    */
-  buildEnv: EnvConfig;
+  buildEnv: Env;
 
   /**
    * environment variables from `.env` file
    */
-  runEnv: EnvConfig;
+  runEnv: Env;
 
   /**
    * environment variables from `.env` and `.env.build`
    */
-  allEnv: EnvConfig;
+  allEnv: Env;
 }
 
 export interface BuildMatch extends BuildConfig {
@@ -53,8 +53,6 @@ export interface BuildMatch extends BuildConfig {
   buildProcess?: ChildProcess;
 }
 
-export type RouteConfig = Route;
-
 export interface HttpHandler {
   (req: http.IncomingMessage, res: http.ServerResponse): void;
 }
@@ -63,9 +61,9 @@ export interface BuilderInputs {
   [path: string]: FileFsRef;
 }
 
-export type BuiltLambda = Lambda & {
+export interface BuiltLambda extends Lambda {
   fn?: FunLambda;
-};
+}
 
 export type BuilderOutput = BuiltLambda | FileFsRef | FileBlob;
 
@@ -79,21 +77,6 @@ export interface CacheOutputs {
   [path: string]: CacheOutput;
 }
 
-export interface BuilderParamsBase {
-  files: BuilderInputs;
-  entrypoint: string;
-  config: Config;
-  meta?: Meta;
-}
-
-export interface BuilderParams extends BuilderParamsBase {
-  workPath: string;
-}
-
-export interface PrepareCacheParams extends BuilderParams {
-  cachePath: string;
-}
-
 export interface BuilderConfigAttr {
   maxLambdaSize?: string | number;
 }
@@ -102,49 +85,43 @@ export interface Builder {
   version?: 1 | 2 | 3 | 4;
   config?: BuilderConfigAttr;
   build(
-    params: BuilderParams
+    opts: BuildOptions
   ):
     | BuilderOutputs
     | BuildResult
     | Promise<BuilderOutputs>
     | Promise<BuildResult>;
-  shouldServe?(params: ShouldServeParams): boolean | Promise<boolean>;
   prepareCache?(
-    params: PrepareCacheParams
+    opts: PrepareCacheOptions
   ): CacheOutputs | Promise<CacheOutputs>;
+  shouldServe?(params: ShouldServeOptions): boolean | Promise<boolean>;
+  startDevServer?(opts: StartDevServerOptions): Promise<StartDevServerResult>;
 }
 
 export interface BuildResult {
   output: BuilderOutputs;
-  routes: RouteConfig[];
+  routes: Route[];
   watch: string[];
   distPath?: string;
 }
 
 export interface BuildResultV3 {
   output: Lambda;
-  routes: RouteConfig[];
+  routes: Route[];
   watch: string[];
   distPath?: string;
 }
 
 export interface BuildResultV4 {
   output: { [filePath: string]: Lambda };
-  routes: RouteConfig[];
+  routes: Route[];
   watch: string[];
   distPath?: string;
 }
 
-export interface ShouldServeParams {
-  files: BuilderInputs;
-  entrypoint: string;
-  config?: Config;
-  requestPath: string;
-  workPath: string;
-}
-
 export interface BuilderWithPackage {
   runInProcess?: boolean;
+  requirePath: string;
   builder: Readonly<Builder>;
   package: Readonly<PackageJson>;
 }
@@ -167,7 +144,7 @@ export interface RouteResult {
   // "uri_args": <object (key=value) list of new uri args to be passed along to dest >
   uri_args?: { [key: string]: any };
   // "matched_route": <object of the route spec that matched>
-  matched_route?: RouteConfig;
+  matched_route?: Route;
   // "matched_route_idx": <integer of the index of the route matched>
   matched_route_idx?: number;
   // "userDest": <boolean in case the destination was user defined>
diff --git a/packages/now-cli/src/util/dev/yarn-installer.ts b/packages/now-cli/src/util/dev/yarn-installer.ts
deleted file mode 100644
index 7ea3d0807..000000000
--- a/packages/now-cli/src/util/dev/yarn-installer.ts
+++ /dev/null
@@ -1,103 +0,0 @@
-import { createHash } from 'crypto';
-import {
-  mkdirp,
-  createWriteStream,
-  writeFile,
-  statSync,
-  chmodSync,
-  createReadStream,
-} from 'fs-extra';
-import pipe from 'promisepipe';
-import { join } from 'path';
-import fetch from 'node-fetch';
-import { Output } from '../output/create-output';
-import { builderDirPromise } from './builder-cache';
-
-const YARN_VERSION = '1.17.3';
-const YARN_SHA = '77f28b2793ca7d0ab5bd5da072afc423f7fdf733';
-const YARN_URL = `https://github.com/yarnpkg/yarn/releases/download/v${YARN_VERSION}/yarn-${YARN_VERSION}.js`;
-
-function plusxSync(file: string): void {
-  const s = statSync(file);
-  const newMode = s.mode | 64 | 8 | 1;
-
-  if (s.mode === newMode) {
-    return;
-  }
-
-  const base8 = newMode.toString(8).slice(-3);
-  chmodSync(file, base8);
-}
-
-function getSha1(filePath: string): Promise<string | null> {
-  return new Promise((resolve, reject) => {
-    const hash = createHash('sha1');
-    const stream = createReadStream(filePath);
-    stream.on('error', err => {
-      if (err.code === 'ENOENT') {
-        resolve(null);
-      } else {
-        reject(err);
-      }
-    });
-    stream.on('data', chunk => hash.update(chunk));
-    stream.on('end', () => resolve(hash.digest('hex')));
-  });
-}
-
-async function installYarn(output: Output): Promise<string> {
-  // Loosely based on https://yarnpkg.com/install.sh
-  const dirName = await builderDirPromise;
-  const yarnBin = join(dirName, 'yarn');
-  const sha1 = await getSha1(yarnBin);
-
-  if (sha1 === YARN_SHA) {
-    output.debug('The yarn executable is already cached, not re-downloading');
-    return dirName;
-  }
-
-  output.debug(`Creating directory ${dirName}`);
-  await mkdirp(dirName);
-  output.debug(`Finished creating ${dirName}`);
-
-  output.debug(`Downloading ${YARN_URL}`);
-  const response = await fetch(YARN_URL, {
-    compress: false,
-    redirect: 'follow',
-  });
-
-  if (response.status !== 200) {
-    throw new Error(`Received invalid response: ${await response.text()}`);
-  }
-
-  const target = createWriteStream(yarnBin);
-  await pipe(
-    response.body,
-    target
-  );
-  output.debug(`Finished downloading yarn ${yarnBin}`);
-
-  output.debug(`Making the yarn binary executable`);
-  plusxSync(yarnBin);
-  output.debug(`Finished making the yarn binary executable`);
-
-  if (process.platform === 'win32') {
-    // The `yarn.cmd` file is necessary for `yarn` to be executable
-    // when running `now dev` through cmd.exe
-    await writeFile(
-      `${yarnBin}.cmd`,
-      [
-        '@echo off',
-        '@SETLOCAL',
-        '@SET PATHEXT=%PATHEXT:;.JS;=;%',
-        'node "%~dp0\\yarn" %*',
-      ].join('\r\n')
-    );
-  }
-
-  return dirName;
-}
-
-export async function getYarnPath(output: Output): Promise<string> {
-  return installYarn(output);
-}
diff --git a/packages/now-cli/src/util/once.ts b/packages/now-cli/src/util/once.ts
deleted file mode 100644
index 6d80bf831..000000000
--- a/packages/now-cli/src/util/once.ts
+++ /dev/null
@@ -1,20 +0,0 @@
-import { EventEmitter } from 'events';
-
-export function once<T>(emitter: EventEmitter, name: string): Promise<T> {
-  return new Promise((resolve, reject) => {
-    function cleanup() {
-      emitter.removeListener(name, onEvent);
-      emitter.removeListener('error', onError);
-    }
-    function onEvent(arg: T) {
-      cleanup();
-      resolve(arg);
-    }
-    function onError(err: Error) {
-      cleanup();
-      reject(err);
-    }
-    emitter.on(name, onEvent);
-    emitter.on('error', onError);
-  });
-}
diff --git a/packages/now-cli/src/util/pkg.ts b/packages/now-cli/src/util/pkg.ts
index 4ca82a681..387bf1747 100644
--- a/packages/now-cli/src/util/pkg.ts
+++ b/packages/now-cli/src/util/pkg.ts
@@ -1,13 +1,6 @@
-import path from 'path';
-import pkg from '../../package.json';
+import _pkg from '../../package.json';
+import { PackageJson } from '@vercel/build-utils';
 
-try {
-  const distDir = path.dirname(process.execPath);
-  // @ts-ignore
-  pkg._npmPkg = require(`${path.join(distDir, '../../package.json')}`);
-} catch (err) {
-  // @ts-ignore
-  pkg._npmPkg = null;
-}
+const pkg: PackageJson = _pkg;
 
 export default pkg;
diff --git a/packages/now-cli/src/util/tree-kill.ts b/packages/now-cli/src/util/tree-kill.ts
new file mode 100644
index 000000000..31ea894e4
--- /dev/null
+++ b/packages/now-cli/src/util/tree-kill.ts
@@ -0,0 +1,4 @@
+import _treeKill from 'tree-kill';
+import { promisify } from 'util';
+
+export const treeKill = promisify(_treeKill);
diff --git a/packages/now-cli/test/dev-builder.unit.js b/packages/now-cli/test/dev-builder.unit.js
index cd82d029c..2e0a48fca 100644
--- a/packages/now-cli/test/dev-builder.unit.js
+++ b/packages/now-cli/test/dev-builder.unit.js
@@ -1,17 +1,23 @@
 import test from 'ava';
-import { filterPackage } from '../src/util/dev/builder-cache';
+import npa from 'npm-package-arg';
+import { filterPackage, isBundledBuilder } from '../src/util/dev/builder-cache';
 
-test('[dev-builder] filter install "latest", cached canary', async t => {
+test('[dev-builder] filter install "latest", cached canary', t => {
   const buildersPkg = {
     dependencies: {
       '@vercel/build-utils': '0.0.1-canary.0',
     },
   };
-  const result = filterPackage('@vercel/build-utils', 'canary', buildersPkg);
+  const result = filterPackage(
+    '@vercel/build-utils',
+    'canary',
+    buildersPkg,
+    {}
+  );
   t.is(result, true);
 });
 
-test('[dev-builder] filter install "canary", cached stable', async t => {
+test('[dev-builder] filter install "canary", cached stable', t => {
   const buildersPkg = {
     dependencies: {
       '@vercel/build-utils': '0.0.1',
@@ -20,22 +26,28 @@ test('[dev-builder] filter install "canary", cached stable', async t => {
   const result = filterPackage(
     '@vercel/build-utils@canary',
     'latest',
-    buildersPkg
+    buildersPkg,
+    {}
   );
   t.is(result, true);
 });
 
-test('[dev-builder] filter install "latest", cached stable', async t => {
+test('[dev-builder] filter install "latest", cached stable', t => {
   const buildersPkg = {
     dependencies: {
       '@vercel/build-utils': '0.0.1',
     },
   };
-  const result = filterPackage('@vercel/build-utils', 'latest', buildersPkg);
+  const result = filterPackage(
+    '@vercel/build-utils',
+    'latest',
+    buildersPkg,
+    {}
+  );
   t.is(result, false);
 });
 
-test('[dev-builder] filter install "canary", cached canary', async t => {
+test('[dev-builder] filter install "canary", cached canary', t => {
   const buildersPkg = {
     dependencies: {
       '@vercel/build-utils': '0.0.1-canary.0',
@@ -44,87 +56,209 @@ test('[dev-builder] filter install "canary", cached canary', async t => {
   const result = filterPackage(
     '@vercel/build-utils@canary',
     'canary',
-    buildersPkg
+    buildersPkg,
+    {}
   );
   t.is(result, false);
 });
 
-test('[dev-builder] filter install URL, cached stable', async t => {
+test('[dev-builder] filter install URL, cached stable', t => {
   const buildersPkg = {
     dependencies: {
       '@vercel/build-utils': '0.0.1',
     },
   };
-  const result = filterPackage('https://tarball.now.sh', 'latest', buildersPkg);
+  const result = filterPackage(
+    'https://tarball.now.sh',
+    'latest',
+    buildersPkg,
+    {}
+  );
   t.is(result, true);
 });
 
-test('[dev-builder] filter install URL, cached canary', async t => {
+test('[dev-builder] filter install URL, cached canary', t => {
   const buildersPkg = {
     dependencies: {
       '@vercel/build-utils': '0.0.1-canary.0',
     },
   };
-  const result = filterPackage('https://tarball.now.sh', 'canary', buildersPkg);
+  const result = filterPackage(
+    'https://tarball.now.sh',
+    'canary',
+    buildersPkg,
+    {}
+  );
   t.is(result, true);
 });
 
-test('[dev-builder] filter install "latest", cached URL - stable', async t => {
+test('[dev-builder] filter install "latest", cached URL - stable', t => {
   const buildersPkg = {
     dependencies: {
       '@vercel/build-utils': 'https://tarball.now.sh',
     },
   };
-  const result = filterPackage('@vercel/build-utils', 'latest', buildersPkg);
+  const result = filterPackage(
+    '@vercel/build-utils',
+    'latest',
+    buildersPkg,
+    {}
+  );
   t.is(result, true);
 });
 
-test('[dev-builder] filter install "latest", cached URL - canary', async t => {
+test('[dev-builder] filter install "latest", cached URL - canary', t => {
   const buildersPkg = {
     dependencies: {
       '@vercel/build-utils': 'https://tarball.now.sh',
     },
   };
-  const result = filterPackage('@vercel/build-utils', 'canary', buildersPkg);
+  const result = filterPackage(
+    '@vercel/build-utils',
+    'canary',
+    buildersPkg,
+    {}
+  );
   t.is(result, true);
 });
 
-test('[dev-builder] filter install not bundled version, cached same version', async t => {
+test('[dev-builder] filter install not bundled version, cached same version', t => {
   const buildersPkg = {
     dependencies: {
       'not-bundled-package': '0.0.1',
     },
   };
-  const result = filterPackage('not-bundled-package@0.0.1', '_', buildersPkg);
+  const result = filterPackage(
+    'not-bundled-package@0.0.1',
+    '_',
+    buildersPkg,
+    {}
+  );
   t.is(result, false);
 });
 
-test('[dev-builder] filter install not bundled version, cached different version', async t => {
+test('[dev-builder] filter install not bundled version, cached different version', t => {
   const buildersPkg = {
     dependencies: {
       'not-bundled-package': '0.0.9',
     },
   };
-  const result = filterPackage('not-bundled-package@0.0.1', '_', buildersPkg);
+  const result = filterPackage(
+    'not-bundled-package@0.0.1',
+    '_',
+    buildersPkg,
+    {}
+  );
   t.is(result, true);
 });
 
-test('[dev-builder] filter install not bundled stable, cached version', async t => {
+test('[dev-builder] filter install not bundled stable, cached version', t => {
   const buildersPkg = {
     dependencies: {
       'not-bundled-package': '0.0.1',
     },
   };
-  const result = filterPackage('not-bundled-package', '_', buildersPkg);
+  const result = filterPackage('not-bundled-package', '_', buildersPkg, {});
   t.is(result, true);
 });
 
-test('[dev-builder] filter install not bundled tagged, cached tagged', async t => {
+test('[dev-builder] filter install not bundled tagged, cached tagged', t => {
   const buildersPkg = {
     dependencies: {
       'not-bundled-package': '16.9.0-alpha.0',
     },
   };
-  const result = filterPackage('not-bundled-package@alpha', '_', buildersPkg);
+  const result = filterPackage(
+    'not-bundled-package@alpha',
+    '_',
+    buildersPkg,
+    {}
+  );
   t.is(result, true);
 });
+
+test('[dev-builder] isBundledBuilder() - stable', t => {
+  const nowCliPkg = {
+    dependencies: {
+      '@now/node': '1.5.2',
+    },
+  };
+
+  // "canary" tag
+  {
+    const parsed = npa('@now/node@canary');
+    const result = isBundledBuilder(parsed, nowCliPkg);
+    t.is(result, false);
+  }
+
+  // "latest" tag
+  {
+    const parsed = npa('@now/node');
+    const result = isBundledBuilder(parsed, nowCliPkg);
+    t.is(result, true);
+  }
+
+  // specific matching version
+  {
+    const parsed = npa('@now/node@1.5.2');
+    const result = isBundledBuilder(parsed, nowCliPkg);
+    t.is(result, true);
+  }
+
+  // specific non-matching version
+  {
+    const parsed = npa('@now/node@1.5.1');
+    const result = isBundledBuilder(parsed, nowCliPkg);
+    t.is(result, false);
+  }
+
+  // URL
+  {
+    const parsed = npa('https://example.com');
+    const result = isBundledBuilder(parsed, nowCliPkg);
+    t.is(result, false);
+  }
+});
+
+test('[dev-builder] isBundledBuilder() - canary', t => {
+  const nowCliPkg = {
+    dependencies: {
+      '@now/node': '1.5.2-canary.3',
+    },
+  };
+
+  // "canary" tag
+  {
+    const parsed = npa('@now/node@canary');
+    const result = isBundledBuilder(parsed, nowCliPkg);
+    t.is(result, true);
+  }
+
+  // "latest" tag
+  {
+    const parsed = npa('@now/node');
+    const result = isBundledBuilder(parsed, nowCliPkg);
+    t.is(result, false);
+  }
+
+  // specific matching version
+  {
+    const parsed = npa('@now/node@1.5.2-canary.3');
+    const result = isBundledBuilder(parsed, nowCliPkg);
+    t.is(result, true);
+  }
+
+  // specific non-matching version
+  {
+    const parsed = npa('@now/node@1.5.2-canary.2');
+    const result = isBundledBuilder(parsed, nowCliPkg);
+    t.is(result, false);
+  }
+
+  // URL
+  {
+    const parsed = npa('https://example.com');
+    const result = isBundledBuilder(parsed, nowCliPkg);
+    t.is(result, false);
+  }
+});
diff --git a/packages/now-cli/test/dev-server.unit.js b/packages/now-cli/test/dev-server.unit.js
index b005af17a..8d8164be7 100644
--- a/packages/now-cli/test/dev-server.unit.js
+++ b/packages/now-cli/test/dev-server.unit.js
@@ -289,6 +289,7 @@ test(
   testFixture('now-dev-static-routes', async (t, server) => {
     {
       const res = await fetch(`${server.address}/`);
+      t.is(res.status, 200);
       const body = await res.text();
       t.is(body, '<body>Hello!</body>\n');
     }
@@ -300,6 +301,7 @@ test(
   testFixture('now-dev-static-build-routing', async (t, server) => {
     {
       const res = await fetch(`${server.address}/api/date`);
+      t.is(res.status, 200);
       const body = await res.text();
       t.is(body.startsWith('The current date:'), true);
     }
diff --git a/packages/now-cli/test/dev/fixtures/26-nextjs-secrets/yarn.lock b/packages/now-cli/test/dev/fixtures/26-nextjs-secrets/yarn.lock
index 24954e443..ab047df16 100644
--- a/packages/now-cli/test/dev/fixtures/26-nextjs-secrets/yarn.lock
+++ b/packages/now-cli/test/dev/fixtures/26-nextjs-secrets/yarn.lock
@@ -1074,11 +1074,6 @@
   resolved "https://registry.yarnpkg.com/@xtuc/long/-/long-4.2.2.tgz#d291c6a4e97989b5c61d9acf396ae4fe133a718d"
   integrity sha512-NuHqBY1PB/D8xU6s/thBgOAiAP7HOYDQ32+BFZILJ8ivkUkAHQnWfn6WhL79Owj1qmUnoN/YPhktdIoucipkAQ==
 
-abbrev@1:
-  version "1.1.1"
-  resolved "https://registry.yarnpkg.com/abbrev/-/abbrev-1.1.1.tgz#f8f2c887ad10bf67f634f005b6987fed3179aac8"
-  integrity sha512-nne9/IiQ/hzIhY6pdDnbBtz7DjPTKrY00P/zvPSm5pOFkl6xuGrGnXn/VtTNNfNtAfZ9/1RtehkszU9qcTii0Q==
-
 accepts@~1.3.5:
   version "1.3.7"
   resolved "https://registry.yarnpkg.com/accepts/-/accepts-1.3.7.tgz#531bc726517a3b2b41f850021c6cc15eaab507cd"
@@ -1147,11 +1142,6 @@ ansi-regex@^2.0.0:
   resolved "https://registry.yarnpkg.com/ansi-regex/-/ansi-regex-2.1.1.tgz#c3b33ab5ee360d86e0e628f0468ae7ef27d654df"
   integrity sha1-w7M6te42DYbg5ijwRorn7yfWVN8=
 
-ansi-regex@^3.0.0:
-  version "3.0.0"
-  resolved "https://registry.yarnpkg.com/ansi-regex/-/ansi-regex-3.0.0.tgz#ed0317c322064f79466c02966bddb605ab37d998"
-  integrity sha1-7QMXwyIGT3lGbAKWa922Bas32Zg=
-
 ansi-regex@^4.1.0:
   version "4.1.0"
   resolved "https://registry.yarnpkg.com/ansi-regex/-/ansi-regex-4.1.0.tgz#8b9f8f08cf1acb843756a839ca8c7e3168c51997"
@@ -1185,19 +1175,11 @@ anymatch@~3.1.1:
     normalize-path "^3.0.0"
     picomatch "^2.0.4"
 
-aproba@^1.0.3, aproba@^1.1.1:
+aproba@^1.1.1:
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/aproba/-/aproba-1.2.0.tgz#6802e6264efd18c790a1b0d517f0f2627bf2c94a"
   integrity sha512-Y9J6ZjXtoYh8RnXVCMOU/ttDmk1aBjunq9vO0ta5x85WDQiQfUF9sIPBITdbiiIVcBo03Hi3jMxigBtsddlXRw==
 
-are-we-there-yet@~1.1.2:
-  version "1.1.5"
-  resolved "https://registry.yarnpkg.com/are-we-there-yet/-/are-we-there-yet-1.1.5.tgz#4b35c2944f062a8bfcda66410760350fe9ddfc21"
-  integrity sha512-5hYdAkZlcG8tOLujVDTgCT+uPX0VnpAH28gWsLfzpXYm7wP6mp5Q/gYyR7YQ0cKVJcXJnl3j2kpBan13PtQf6w==
-  dependencies:
-    delegates "^1.0.0"
-    readable-stream "^2.0.6"
-
 argparse@^1.0.7:
   version "1.0.10"
   resolved "https://registry.yarnpkg.com/argparse/-/argparse-1.0.10.tgz#bcd6791ea5ae09725e17e5ad988134cd40b3d911"
@@ -1809,11 +1791,6 @@ clone@^1.0.2:
   resolved "https://registry.yarnpkg.com/clone/-/clone-1.0.4.tgz#da309cc263df15994c688ca902179ca3c7cd7c7e"
   integrity sha1-2jCcwmPfFZlMaIypAheco8fNfH4=
 
-code-point-at@^1.0.0:
-  version "1.1.0"
-  resolved "https://registry.yarnpkg.com/code-point-at/-/code-point-at-1.1.0.tgz#0d070b4d043a5bea33a2f1a40e2edb3d9a4ccf77"
-  integrity sha1-DQcLTQQ6W+ozovGkDi7bPZpMz3c=
-
 collection-visit@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/collection-visit/-/collection-visit-1.0.0.tgz#4bc0373c164bc3291b4d368c829cf1a80a59dca0"
@@ -1921,11 +1898,6 @@ console-browserify@^1.1.0:
   resolved "https://registry.yarnpkg.com/console-browserify/-/console-browserify-1.2.0.tgz#67063cef57ceb6cf4993a2ab3a55840ae8c49336"
   integrity sha512-ZMkYO/LkF17QvCPqM0gxw8yUzigAOZOSWSHg91FH6orS7vcEj5dVZTidN2fQ14yBSdg97RqhSNwLUXInd52OTA==
 
-console-control-strings@^1.0.0, console-control-strings@~1.1.0:
-  version "1.1.0"
-  resolved "https://registry.yarnpkg.com/console-control-strings/-/console-control-strings-1.1.0.tgz#3d7cf4464db6446ea644bf4b39507f9851008e8e"
-  integrity sha1-PXz0Rk22RG6mRL9LOVB/mFEAjo4=
-
 constants-browserify@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/constants-browserify/-/constants-browserify-1.0.0.tgz#c20b96d8c617748aaf1c16021760cd27fcb8cb75"
@@ -2154,7 +2126,7 @@ debug@2.6.9, debug@^2.2.0, debug@^2.3.3:
   dependencies:
     ms "2.0.0"
 
-debug@^3.0.0, debug@^3.2.6:
+debug@^3.0.0:
   version "3.2.6"
   resolved "https://registry.yarnpkg.com/debug/-/debug-3.2.6.tgz#e83d17de16d8a7efb7717edbe5fb10135eee629b"
   integrity sha512-mel+jf7nrtEl5Pn1Qx46zARXKDpBbvzezse7p7LqINmdoIk8PYP5SySaxEmYv6TZ0JyEKA1hsCId6DIhgITtWQ==
@@ -2173,11 +2145,6 @@ decode-uri-component@^0.2.0:
   resolved "https://registry.yarnpkg.com/decode-uri-component/-/decode-uri-component-0.2.0.tgz#eb3913333458775cb84cd1a1fae062106bb87545"
   integrity sha1-6zkTMzRYd1y4TNGh+uBiEGu4dUU=
 
-deep-extend@^0.6.0:
-  version "0.6.0"
-  resolved "https://registry.yarnpkg.com/deep-extend/-/deep-extend-0.6.0.tgz#c4fa7c95404a17a9c3e8ca7e1537312b736330ac"
-  integrity sha512-LOHxIOaPYdHlJRtCQfDIVZtfw/ufM8+rVj649RIHzcm/vGwQRXFt6OPqIFWsm2XEMrNIEtWR64sY1LEKD2vAOA==
-
 defaults@^1.0.3:
   version "1.0.3"
   resolved "https://registry.yarnpkg.com/defaults/-/defaults-1.0.3.tgz#c656051e9817d9ff08ed881477f3fe4019f3ef7d"
@@ -2226,11 +2193,6 @@ del@^3.0.0:
     pify "^3.0.0"
     rimraf "^2.2.8"
 
-delegates@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/delegates/-/delegates-1.0.0.tgz#84c6e159b81904fdca59a0ef44cd870d31250f9a"
-  integrity sha1-hMbhWbgZBP3KWaDvRM2HDTElD5o=
-
 depd@~1.1.2:
   version "1.1.2"
   resolved "https://registry.yarnpkg.com/depd/-/depd-1.1.2.tgz#9bcd52e14c097763e749b274c4346ed2e560b5a9"
@@ -2249,11 +2211,6 @@ destroy@~1.0.4:
   resolved "https://registry.yarnpkg.com/destroy/-/destroy-1.0.4.tgz#978857442c44749e4206613e37946205826abd80"
   integrity sha1-l4hXRCxEdJ5CBmE+N5RiBYJqvYA=
 
-detect-libc@^1.0.2:
-  version "1.0.3"
-  resolved "https://registry.yarnpkg.com/detect-libc/-/detect-libc-1.0.3.tgz#fa137c4bd698edf55cd5cd02ac559f91a4c4ba9b"
-  integrity sha1-+hN8S9aY7fVc1c0CrFWfkaTEups=
-
 devalue@2.0.1:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/devalue/-/devalue-2.0.1.tgz#5d368f9adc0928e47b77eea53ca60d2f346f9762"
@@ -2717,13 +2674,6 @@ from2@^2.1.0:
     inherits "^2.0.1"
     readable-stream "^2.0.0"
 
-fs-minipass@^1.2.5:
-  version "1.2.7"
-  resolved "https://registry.yarnpkg.com/fs-minipass/-/fs-minipass-1.2.7.tgz#ccff8570841e7fe4265693da88936c55aed7f7c7"
-  integrity sha512-GWSSJGFy4e9GUeCcbIkED+bgAoFyj7XF1mV8rma3QW4NIqX9Kyx79N/PF61H5udOV3aY1IaMLs6pGbH71nlCTA==
-  dependencies:
-    minipass "^2.6.0"
-
 fs-write-stream-atomic@^1.0.8:
   version "1.0.10"
   resolved "https://registry.yarnpkg.com/fs-write-stream-atomic/-/fs-write-stream-atomic-1.0.10.tgz#b47df53493ef911df75731e70a9ded0189db40c9"
@@ -2757,20 +2707,6 @@ function-bind@^1.1.1:
   resolved "https://registry.yarnpkg.com/function-bind/-/function-bind-1.1.1.tgz#a56899d3ea3c9bab874bb9773b7c5ede92f4895d"
   integrity sha512-yIovAzMX49sF8Yl58fSCWJ5svSLuaibPxXQJFLmBObTuCr0Mf1KiPopGM9NiFjiYBCbfaa2Fh6breQ6ANVTI0A==
 
-gauge@~2.7.3:
-  version "2.7.4"
-  resolved "https://registry.yarnpkg.com/gauge/-/gauge-2.7.4.tgz#2c03405c7538c39d7eb37b317022e325fb018bf7"
-  integrity sha1-LANAXHU4w51+s3sxcCLjJfsBi/c=
-  dependencies:
-    aproba "^1.0.3"
-    console-control-strings "^1.0.0"
-    has-unicode "^2.0.0"
-    object-assign "^4.1.0"
-    signal-exit "^3.0.0"
-    string-width "^1.0.1"
-    strip-ansi "^3.0.1"
-    wide-align "^1.1.0"
-
 get-value@^2.0.3, get-value@^2.0.6:
   version "2.0.6"
   resolved "https://registry.yarnpkg.com/get-value/-/get-value-2.0.6.tgz#dc15ca1c672387ca76bd37ac0a395ba2042a2c28"
@@ -2859,11 +2795,6 @@ has-symbols@^1.0.0:
   resolved "https://registry.yarnpkg.com/has-symbols/-/has-symbols-1.0.1.tgz#9f5214758a44196c406d9bd76cebf81ec2dd31e8"
   integrity sha512-PLcsoqu++dmEIZB+6totNFKq/7Do+Z0u4oT0zKOJNl3lYK6vGwwu2hjHs+68OEZbTjiUE9bgOABXbP/GvrS0Kg==
 
-has-unicode@^2.0.0:
-  version "2.0.1"
-  resolved "https://registry.yarnpkg.com/has-unicode/-/has-unicode-2.0.1.tgz#e0e6fe6a28cf51138855e086d1691e771de2a8b9"
-  integrity sha1-4Ob+aijPUROIVeCG0Wkedx3iqLk=
-
 has-value@^0.3.1:
   version "0.3.1"
   resolved "https://registry.yarnpkg.com/has-value/-/has-value-0.3.1.tgz#7b1f58bada62ca827ec0a2078025654845995e1f"
@@ -2984,7 +2915,7 @@ https-browserify@^1.0.0:
   resolved "https://registry.yarnpkg.com/https-browserify/-/https-browserify-1.0.0.tgz#ec06c10e0a34c0f2faf199f7fd7fc78fffd03c73"
   integrity sha1-7AbBDgo0wPL68Zn3/X/Hj//QPHM=
 
-iconv-lite@0.4.24, iconv-lite@^0.4.4:
+iconv-lite@0.4.24:
   version "0.4.24"
   resolved "https://registry.yarnpkg.com/iconv-lite/-/iconv-lite-0.4.24.tgz#2022b4b25fbddc21d2f524974a474aafe733908b"
   integrity sha512-v3MXnZAcvnywkTUEZomIActle7RXXeedOR31wwl7VlyoXO4Qi9arvSenNQWne1TcRwhCL1HwLI21bEqdpj8/rA==
@@ -3013,13 +2944,6 @@ ignore-loader@0.1.2:
   resolved "https://registry.yarnpkg.com/ignore-loader/-/ignore-loader-0.1.2.tgz#d81f240376d0ba4f0d778972c3ad25874117a463"
   integrity sha1-2B8kA3bQuk8Nd4lyw60lh0EXpGM=
 
-ignore-walk@^3.0.1:
-  version "3.0.3"
-  resolved "https://registry.yarnpkg.com/ignore-walk/-/ignore-walk-3.0.3.tgz#017e2447184bfeade7c238e4aefdd1e8f95b1e37"
-  integrity sha512-m7o6xuOaT1aqheYHKf8W6J5pYH85ZI9w077erOzLje3JsB1gkafkAhHHY19dqjulgIZHFm32Cp5uNZgcQqdJKw==
-  dependencies:
-    minimatch "^3.0.4"
-
 import-cwd@^2.0.0:
   version "2.1.0"
   resolved "https://registry.yarnpkg.com/import-cwd/-/import-cwd-2.1.0.tgz#aa6cf36e722761285cb371ec6519f53e2435b0a9"
@@ -3080,11 +3004,6 @@ inherits@2.0.3:
   resolved "https://registry.yarnpkg.com/inherits/-/inherits-2.0.3.tgz#633c2c83e3da42a502f52466022480f4208261de"
   integrity sha1-Yzwsg+PaQqUC9SRmAiSA9CCCYd4=
 
-ini@~1.3.0:
-  version "1.3.5"
-  resolved "https://registry.yarnpkg.com/ini/-/ini-1.3.5.tgz#eee25f56db1c9ec6085e0c22778083f596abf927"
-  integrity sha512-RZY5huIKCMRWDUqZlEi72f/lmXKMvuszcMBduliQ3nnWbx9X/ZBQO7DijMEYS9EhHBb2qacRUMtC7svLwe0lcw==
-
 invariant@^2.2.2:
   version "2.2.4"
   resolved "https://registry.yarnpkg.com/invariant/-/invariant-2.2.4.tgz#610f3c92c9359ce1db616e538008d23ff35158e6"
@@ -3189,18 +3108,6 @@ is-extglob@^2.1.0, is-extglob@^2.1.1:
   resolved "https://registry.yarnpkg.com/is-extglob/-/is-extglob-2.1.1.tgz#a88c02535791f02ed37c76a1b9ea9773c833f8c2"
   integrity sha1-qIwCU1eR8C7TfHahueqXc8gz+MI=
 
-is-fullwidth-code-point@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/is-fullwidth-code-point/-/is-fullwidth-code-point-1.0.0.tgz#ef9e31386f031a7f0d643af82fde50c457ef00cb"
-  integrity sha1-754xOG8DGn8NZDr4L95QxFfvAMs=
-  dependencies:
-    number-is-nan "^1.0.0"
-
-is-fullwidth-code-point@^2.0.0:
-  version "2.0.0"
-  resolved "https://registry.yarnpkg.com/is-fullwidth-code-point/-/is-fullwidth-code-point-2.0.0.tgz#a3b30a5c4f199183167aaab93beefae3ddfb654f"
-  integrity sha1-o7MKXE8ZkYMWeqq5O+764937ZU8=
-
 is-glob@^3.1.0:
   version "3.1.0"
   resolved "https://registry.yarnpkg.com/is-glob/-/is-glob-3.1.0.tgz#7ba5ae24217804ac70707b96922567486cc3e84a"
@@ -3749,21 +3656,6 @@ minimist@^1.2.0, minimist@^1.2.5:
   resolved "https://registry.yarnpkg.com/minimist/-/minimist-1.2.5.tgz#67d66014b66a6a8aaa0c083c5fd58df4e4e97602"
   integrity sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw==
 
-minipass@^2.6.0, minipass@^2.8.6, minipass@^2.9.0:
-  version "2.9.0"
-  resolved "https://registry.yarnpkg.com/minipass/-/minipass-2.9.0.tgz#e713762e7d3e32fed803115cf93e04bca9fcc9a6"
-  integrity sha512-wxfUjg9WebH+CUDX/CdbRlh5SmfZiy/hpkxaRI16Y9W56Pa75sWgd/rvFilSgrauD9NyFymP/+JFV3KwzIsJeg==
-  dependencies:
-    safe-buffer "^5.1.2"
-    yallist "^3.0.0"
-
-minizlib@^1.2.1:
-  version "1.3.3"
-  resolved "https://registry.yarnpkg.com/minizlib/-/minizlib-1.3.3.tgz#2290de96818a34c29551c8a8d301216bd65a861d"
-  integrity sha512-6ZYMOEnmVsdCeTJVE0W9ZD+pVnE8h9Hma/iOwwRDsdQoePpoX56/8B6z3P9VNwppJuBKNRuFDRNRqRWexT9G9Q==
-  dependencies:
-    minipass "^2.9.0"
-
 mississippi@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/mississippi/-/mississippi-3.0.0.tgz#ea0a3291f97e0b5e8776b363d5f0a12d94c67022"
@@ -3795,7 +3687,7 @@ mkdirp@0.5.1:
   dependencies:
     minimist "0.0.8"
 
-mkdirp@^0.5.0, mkdirp@^0.5.1:
+mkdirp@^0.5.1:
   version "0.5.5"
   resolved "https://registry.yarnpkg.com/mkdirp/-/mkdirp-0.5.5.tgz#d91cefd62d1436ca0f41620e251288d420099def"
   integrity sha512-NKmAlESf6jMGym1++R0Ra7wvhV+wFW63FaSOFPwRahvea0gMUcGUhVeAg/0BC0wiv9ih5NYPB1Wn1UEI1/L+xQ==
@@ -3851,15 +3743,6 @@ nanomatch@^1.2.9:
     snapdragon "^0.8.1"
     to-regex "^3.0.1"
 
-needle@^2.2.1:
-  version "2.4.1"
-  resolved "https://registry.yarnpkg.com/needle/-/needle-2.4.1.tgz#14af48732463d7475696f937626b1b993247a56a"
-  integrity sha512-x/gi6ijr4B7fwl6WYL9FwlCvRQKGlUNvnceho8wxkwXqN8jvVmmmATTmZPRRG7b/yC1eode26C2HO9jl78Du9g==
-  dependencies:
-    debug "^3.2.6"
-    iconv-lite "^0.4.4"
-    sax "^1.2.4"
-
 negotiator@0.6.2:
   version "0.6.2"
   resolved "https://registry.yarnpkg.com/negotiator/-/negotiator-0.6.2.tgz#feacf7ccf525a77ae9634436a64883ffeca346fb"
@@ -4007,35 +3890,11 @@ node-libs-browser@^2.2.1:
     util "^0.11.0"
     vm-browserify "^1.0.1"
 
-node-pre-gyp@*:
-  version "0.14.0"
-  resolved "https://registry.yarnpkg.com/node-pre-gyp/-/node-pre-gyp-0.14.0.tgz#9a0596533b877289bcad4e143982ca3d904ddc83"
-  integrity sha512-+CvDC7ZttU/sSt9rFjix/P05iS43qHCOOGzcr3Ry99bXG7VX953+vFyEuph/tfqoYu8dttBkE86JSKBO2OzcxA==
-  dependencies:
-    detect-libc "^1.0.2"
-    mkdirp "^0.5.1"
-    needle "^2.2.1"
-    nopt "^4.0.1"
-    npm-packlist "^1.1.6"
-    npmlog "^4.0.2"
-    rc "^1.2.7"
-    rimraf "^2.6.1"
-    semver "^5.3.0"
-    tar "^4.4.2"
-
 node-releases@^1.1.44, node-releases@^1.1.53:
   version "1.1.53"
   resolved "https://registry.yarnpkg.com/node-releases/-/node-releases-1.1.53.tgz#2d821bfa499ed7c5dffc5e2f28c88e78a08ee3f4"
   integrity sha512-wp8zyQVwef2hpZ/dJH7SfSrIPD6YoJz6BDQDpGEkcA0s3LpAQoxBIYmfIq6QAhC1DhwsyCgTaTTcONwX8qzCuQ==
 
-nopt@^4.0.1:
-  version "4.0.3"
-  resolved "https://registry.yarnpkg.com/nopt/-/nopt-4.0.3.tgz#a375cad9d02fd921278d954c2254d5aa57e15e48"
-  integrity sha512-CvaGwVMztSMJLOeXPrez7fyfObdZqNUK1cPAEzLHrTybIua9pMdmmPR5YwtfNftIOMv3DPUhFaxsZMNTQO20Kg==
-  dependencies:
-    abbrev "1"
-    osenv "^0.1.4"
-
 normalize-html-whitespace@1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/normalize-html-whitespace/-/normalize-html-whitespace-1.0.0.tgz#5e3c8e192f1b06c3b9eee4b7e7f28854c7601e34"
@@ -4078,47 +3937,11 @@ normalize-url@1.9.1:
     query-string "^4.1.0"
     sort-keys "^1.0.0"
 
-npm-bundled@^1.0.1:
-  version "1.1.1"
-  resolved "https://registry.yarnpkg.com/npm-bundled/-/npm-bundled-1.1.1.tgz#1edd570865a94cdb1bc8220775e29466c9fb234b"
-  integrity sha512-gqkfgGePhTpAEgUsGEgcq1rqPXA+tv/aVBlgEzfXwA1yiUJF7xtEt3CtVwOjNYQOVknDk0F20w58Fnm3EtG0fA==
-  dependencies:
-    npm-normalize-package-bin "^1.0.1"
-
-npm-normalize-package-bin@^1.0.1:
-  version "1.0.1"
-  resolved "https://registry.yarnpkg.com/npm-normalize-package-bin/-/npm-normalize-package-bin-1.0.1.tgz#6e79a41f23fd235c0623218228da7d9c23b8f6e2"
-  integrity sha512-EPfafl6JL5/rU+ot6P3gRSCpPDW5VmIzX959Ob1+ySFUuuYHWHekXpwdUZcKP5C+DS4GEtdJluwBjnsNDl+fSA==
-
-npm-packlist@^1.1.6:
-  version "1.4.8"
-  resolved "https://registry.yarnpkg.com/npm-packlist/-/npm-packlist-1.4.8.tgz#56ee6cc135b9f98ad3d51c1c95da22bbb9b2ef3e"
-  integrity sha512-5+AZgwru5IevF5ZdnFglB5wNlHG1AOOuw28WhUq8/8emhBmLv6jX5by4WJCh7lW0uSYZYS6DXqIsyZVIXRZU9A==
-  dependencies:
-    ignore-walk "^3.0.1"
-    npm-bundled "^1.0.1"
-    npm-normalize-package-bin "^1.0.1"
-
-npmlog@^4.0.2:
-  version "4.1.2"
-  resolved "https://registry.yarnpkg.com/npmlog/-/npmlog-4.1.2.tgz#08a7f2a8bf734604779a9efa4ad5cc717abb954b"
-  integrity sha512-2uUqazuKlTaSI/dC8AzicUck7+IrEaOnN/e0jd3Xtt1KcGpwx30v50mL7oPyr/h9bL3E4aZccVwpwP+5W9Vjkg==
-  dependencies:
-    are-we-there-yet "~1.1.2"
-    console-control-strings "~1.1.0"
-    gauge "~2.7.3"
-    set-blocking "~2.0.0"
-
 num2fraction@^1.2.2:
   version "1.2.2"
   resolved "https://registry.yarnpkg.com/num2fraction/-/num2fraction-1.2.2.tgz#6f682b6a027a4e9ddfa4564cd2589d1d4e669ede"
   integrity sha1-b2gragJ6Tp3fpFZM0lidHU5mnt4=
 
-number-is-nan@^1.0.0:
-  version "1.0.1"
-  resolved "https://registry.yarnpkg.com/number-is-nan/-/number-is-nan-1.0.1.tgz#097b602b53422a522c1afb8790318336941a011d"
-  integrity sha1-CXtgK1NCKlIsGvuHkDGDNpQaAR0=
-
 object-assign@4.1.1, object-assign@^4.0.1, object-assign@^4.1.0, object-assign@^4.1.1:
   version "4.1.1"
   resolved "https://registry.yarnpkg.com/object-assign/-/object-assign-4.1.1.tgz#2109adc7965887cfc05cbbd442cac8bfbb360863"
@@ -4210,24 +4033,6 @@ os-browserify@^0.3.0:
   resolved "https://registry.yarnpkg.com/os-browserify/-/os-browserify-0.3.0.tgz#854373c7f5c2315914fc9bfc6bd8238fdda1ec27"
   integrity sha1-hUNzx/XCMVkU/Jv8a9gjj92h7Cc=
 
-os-homedir@^1.0.0:
-  version "1.0.2"
-  resolved "https://registry.yarnpkg.com/os-homedir/-/os-homedir-1.0.2.tgz#ffbc4988336e0e833de0c168c7ef152121aa7fb3"
-  integrity sha1-/7xJiDNuDoM94MFox+8VISGqf7M=
-
-os-tmpdir@^1.0.0:
-  version "1.0.2"
-  resolved "https://registry.yarnpkg.com/os-tmpdir/-/os-tmpdir-1.0.2.tgz#bbe67406c79aa85c5cfec766fe5734555dfa1274"
-  integrity sha1-u+Z0BseaqFxc/sdm/lc0VV36EnQ=
-
-osenv@^0.1.4:
-  version "0.1.5"
-  resolved "https://registry.yarnpkg.com/osenv/-/osenv-0.1.5.tgz#85cdfafaeb28e8677f416e287592b5f3f49ea410"
-  integrity sha512-0CWcCECdMVc2Rw3U5w9ZjqX6ga6ubk1xDVKxtBQPK7wis/0F2r9T6k4ydGYhecl7YUBxBVxhL5oisPsNxAPe2g==
-  dependencies:
-    os-homedir "^1.0.0"
-    os-tmpdir "^1.0.0"
-
 p-limit@^1.1.0:
   version "1.3.0"
   resolved "https://registry.yarnpkg.com/p-limit/-/p-limit-1.3.0.tgz#b86bd5f0c25690911c7590fcbfc2010d54b3ccb8"
@@ -4991,16 +4796,6 @@ raw-body@2.4.0:
     iconv-lite "0.4.24"
     unpipe "1.0.0"
 
-rc@^1.2.7:
-  version "1.2.8"
-  resolved "https://registry.yarnpkg.com/rc/-/rc-1.2.8.tgz#cd924bf5200a075b83c188cd6b9e211b7fc0d3ed"
-  integrity sha512-y3bGgqKj3QBdxLbLkomlohkvsA8gdAiUQlSBJnBhfn+BPxg4bc62d8TcBW15wavDfgexCgccckhcZvywyQYPOw==
-  dependencies:
-    deep-extend "^0.6.0"
-    ini "~1.3.0"
-    minimist "^1.2.0"
-    strip-json-comments "~2.0.1"
-
 react-dom@16.13.0:
   version "16.13.0"
   resolved "https://registry.yarnpkg.com/react-dom/-/react-dom-16.13.0.tgz#cdde54b48eb9e8a0ca1b3dc9943d9bb409b81866"
@@ -5044,7 +4839,7 @@ read-pkg@^2.0.0:
     normalize-package-data "^2.3.2"
     path-type "^2.0.0"
 
-"readable-stream@1 || 2", readable-stream@^2.0.0, readable-stream@^2.0.1, readable-stream@^2.0.2, readable-stream@^2.0.6, readable-stream@^2.1.5, readable-stream@^2.2.2, readable-stream@^2.3.3, readable-stream@^2.3.6, readable-stream@~2.3.6:
+"readable-stream@1 || 2", readable-stream@^2.0.0, readable-stream@^2.0.1, readable-stream@^2.0.2, readable-stream@^2.1.5, readable-stream@^2.2.2, readable-stream@^2.3.3, readable-stream@^2.3.6, readable-stream@~2.3.6:
   version "2.3.7"
   resolved "https://registry.yarnpkg.com/readable-stream/-/readable-stream-2.3.7.tgz#1eca1cf711aef814c04f62252a36a62f6cb23b57"
   integrity sha512-Ebho8K4jIbHAxnuxi7o42OrZgF/ZTNcsZj6nRKyUmkhLFq8CHItp/fy6hQZuZmP/n3yZ9VBUbp4zz/mX8hmYPw==
@@ -5248,7 +5043,7 @@ rework@1.0.1:
     convert-source-map "^0.3.3"
     css "^2.0.0"
 
-rimraf@^2.2.8, rimraf@^2.5.4, rimraf@^2.6.1, rimraf@^2.6.3:
+rimraf@^2.2.8, rimraf@^2.5.4, rimraf@^2.6.3:
   version "2.7.1"
   resolved "https://registry.yarnpkg.com/rimraf/-/rimraf-2.7.1.tgz#35797f13a7fdadc566142c29d4f07ccad483e3ec"
   integrity sha512-uWjbaKIK3T1OSVptzX7Nl6PvQ3qAGtKEtVRjRuazjfL3Bx5eI409VZSqgND+4UNnmzLVdPj9FqFJNPqBZFve4w==
@@ -5303,11 +5098,6 @@ sass-loader@8.0.2:
     schema-utils "^2.6.1"
     semver "^6.3.0"
 
-sax@^1.2.4:
-  version "1.2.4"
-  resolved "https://registry.yarnpkg.com/sax/-/sax-1.2.4.tgz#2816234e2378bddc4e5354fab5caa895df7100d9"
-  integrity sha512-NqVDv9TpANUjFm0N8uM5GxL36UgKi9/atZw+x7YFnQ8ckwFGKrl4xX4yWtrey3UJm5nP1kUbnYgLopqWNSRhWw==
-
 scheduler@^0.19.0:
   version "0.19.1"
   resolved "https://registry.yarnpkg.com/scheduler/-/scheduler-0.19.1.tgz#4f3e2ed2c1a7d65681f4c854fa8c5a1ccb40f196"
@@ -5333,7 +5123,7 @@ schema-utils@^2.0.0, schema-utils@^2.0.1, schema-utils@^2.6.0, schema-utils@^2.6
     ajv "^6.12.0"
     ajv-keywords "^3.4.1"
 
-"semver@2 || 3 || 4 || 5", semver@^5.3.0, semver@^5.4.1, semver@^5.5.0, semver@^5.5.1, semver@^5.6.0:
+"semver@2 || 3 || 4 || 5", semver@^5.4.1, semver@^5.5.0, semver@^5.5.1, semver@^5.6.0:
   version "5.7.1"
   resolved "https://registry.yarnpkg.com/semver/-/semver-5.7.1.tgz#a954f931aeba508d307bbf069eff0c01c96116f7"
   integrity sha512-sauaDf/PZdVgrLTNYHRtpXa1iRiKcaebiKQ1BJdpQlWH2lCvexQdX55snPFyK7QzpudqbCI0qXFfOasHdyNDGQ==
@@ -5372,11 +5162,6 @@ serialize-javascript@^2.1.2:
   resolved "https://registry.yarnpkg.com/serialize-javascript/-/serialize-javascript-2.1.2.tgz#ecec53b0e0317bdc95ef76ab7074b7384785fa61"
   integrity sha512-rs9OggEUF0V4jUSecXazOYsLfu7OGK2qIn3c7IPBiffz32XniEp/TX9Xmc9LQfK2nQ2QKHvZ2oygKUGU0lG4jQ==
 
-set-blocking@~2.0.0:
-  version "2.0.0"
-  resolved "https://registry.yarnpkg.com/set-blocking/-/set-blocking-2.0.0.tgz#045f9782d011ae9a6803ddd382b24392b3d890f7"
-  integrity sha1-BF+XgtARrppoA93TgrJDkrPYkPc=
-
 set-value@^2.0.0, set-value@^2.0.1:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/set-value/-/set-value-2.0.1.tgz#a18d40530e6f07de4228c7defe4227af8cad005b"
@@ -5417,7 +5202,7 @@ shell-quote@^1.6.1:
   resolved "https://registry.yarnpkg.com/shell-quote/-/shell-quote-1.7.2.tgz#67a7d02c76c9da24f99d20808fcaded0e0e04be2"
   integrity sha512-mRz/m/JVscCrkMyPqHc/bczi3OQHkLTqXHEFu0zDhK/qfv3UcOA4SVmRCLmos4bhjr9ekVQubj/R7waKapmiQg==
 
-signal-exit@^3.0.0, signal-exit@^3.0.2:
+signal-exit@^3.0.2:
   version "3.0.3"
   resolved "https://registry.yarnpkg.com/signal-exit/-/signal-exit-3.0.3.tgz#a1410c2edd8f077b08b4e253c8eacfcaf057461c"
   integrity sha512-VUJ49FC8U1OxwZLxIbTTrDvLnf/6TDgxZcK8wxR8zs13xpx7xbG60ndBlhNrFi2EMuFRoeDoJO7wthSLq42EjA==
@@ -5603,23 +5388,6 @@ string-hash@1.1.3:
   resolved "https://registry.yarnpkg.com/string-hash/-/string-hash-1.1.3.tgz#e8aafc0ac1855b4666929ed7dd1275df5d6c811b"
   integrity sha1-6Kr8CsGFW0Zmkp7X3RJ1311sgRs=
 
-string-width@^1.0.1:
-  version "1.0.2"
-  resolved "https://registry.yarnpkg.com/string-width/-/string-width-1.0.2.tgz#118bdf5b8cdc51a2a7e70d211e07e2b0b9b107d3"
-  integrity sha1-EYvfW4zcUaKn5w0hHgfisLmxB9M=
-  dependencies:
-    code-point-at "^1.0.0"
-    is-fullwidth-code-point "^1.0.0"
-    strip-ansi "^3.0.0"
-
-"string-width@^1.0.2 || 2":
-  version "2.1.1"
-  resolved "https://registry.yarnpkg.com/string-width/-/string-width-2.1.1.tgz#ab93f27a8dc13d28cac815c462143a6d9012ae9e"
-  integrity sha512-nOqH59deCq9SRHlxq1Aw85Jnt4w6KvLKqWVik6oA9ZklXLNIOlqg4F2yrT1MVaTjAqvVwdfeZ7w7aCvJD7ugkw==
-  dependencies:
-    is-fullwidth-code-point "^2.0.0"
-    strip-ansi "^4.0.0"
-
 string_decoder@^1.0.0, string_decoder@^1.1.1:
   version "1.3.0"
   resolved "https://registry.yarnpkg.com/string_decoder/-/string_decoder-1.3.0.tgz#42f114594a46cf1a8e30b0a84f56c78c3edac21e"
@@ -5641,30 +5409,18 @@ strip-ansi@5.2.0, strip-ansi@^5.2.0:
   dependencies:
     ansi-regex "^4.1.0"
 
-strip-ansi@^3.0.0, strip-ansi@^3.0.1:
+strip-ansi@^3.0.0:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/strip-ansi/-/strip-ansi-3.0.1.tgz#6a385fb8853d952d5ff05d0e8aaf94278dc63dcf"
   integrity sha1-ajhfuIU9lS1f8F0Oiq+UJ43GPc8=
   dependencies:
     ansi-regex "^2.0.0"
 
-strip-ansi@^4.0.0:
-  version "4.0.0"
-  resolved "https://registry.yarnpkg.com/strip-ansi/-/strip-ansi-4.0.0.tgz#a8479022eb1ac368a871389b635262c505ee368f"
-  integrity sha1-qEeQIusaw2iocTibY1JixQXuNo8=
-  dependencies:
-    ansi-regex "^3.0.0"
-
 strip-bom@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/strip-bom/-/strip-bom-3.0.0.tgz#2334c18e9c759f7bdd56fdef7e9ae3d588e68ed3"
   integrity sha1-IzTBjpx1n3vdVv3vfprj1YjmjtM=
 
-strip-json-comments@~2.0.1:
-  version "2.0.1"
-  resolved "https://registry.yarnpkg.com/strip-json-comments/-/strip-json-comments-2.0.1.tgz#3c531942e908c2697c0ec344858c286c7ca0a60a"
-  integrity sha1-PFMZQukIwml8DsNEhYwobHygpgo=
-
 style-loader@1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/style-loader/-/style-loader-1.0.0.tgz#1d5296f9165e8e2c85d24eee0b7caf9ec8ca1f82"
@@ -5721,19 +5477,6 @@ tapable@^1.0.0, tapable@^1.1.3:
   resolved "https://registry.yarnpkg.com/tapable/-/tapable-1.1.3.tgz#a1fccc06b58db61fd7a45da2da44f5f3a3e67ba2"
   integrity sha512-4WK/bYZmj8xLr+HUCODHGF1ZFzsYffasLUgEiMBY4fgtltdO6B4WJtlSbPaDTLpYTcGVwM2qLnFTICEcNxs3kA==
 
-tar@^4.4.2:
-  version "4.4.13"
-  resolved "https://registry.yarnpkg.com/tar/-/tar-4.4.13.tgz#43b364bc52888d555298637b10d60790254ab525"
-  integrity sha512-w2VwSrBoHa5BsSyH+KxEqeQBAllHhccyMFVHtGtdMpF4W7IRWfZjFiQceJPChOeTsSDVUpER2T8FA93pr0L+QA==
-  dependencies:
-    chownr "^1.1.1"
-    fs-minipass "^1.2.5"
-    minipass "^2.8.6"
-    minizlib "^1.2.1"
-    mkdirp "^0.5.0"
-    safe-buffer "^5.1.2"
-    yallist "^3.0.3"
-
 terser-webpack-plugin@^1.4.1:
   version "1.4.3"
   resolved "https://registry.yarnpkg.com/terser-webpack-plugin/-/terser-webpack-plugin-1.4.3.tgz#5ecaf2dbdc5fb99745fd06791f46fc9ddb1c9a7c"
@@ -6148,13 +5891,6 @@ whatwg-fetch@3.0.0:
   resolved "https://registry.yarnpkg.com/whatwg-fetch/-/whatwg-fetch-3.0.0.tgz#fc804e458cc460009b1a2b966bc8817d2578aefb"
   integrity sha512-9GSJUgz1D4MfyKU7KRqwOjXCXTqWdFNvEr7eUBYchQiVc744mqK/MzXPNR2WsPkmkOa4ywfg8C2n8h+13Bey1Q==
 
-wide-align@^1.1.0:
-  version "1.1.3"
-  resolved "https://registry.yarnpkg.com/wide-align/-/wide-align-1.1.3.tgz#ae074e6bdc0c14a431e804e624549c633b000457"
-  integrity sha512-QGkOQc8XL6Bt5PwnsExKBPuMKBxnGxWWW3fU55Xt4feHozMUhdUMaBCk290qpm/wG5u/RSKzwdAC4i51YigihA==
-  dependencies:
-    string-width "^1.0.2 || 2"
-
 worker-farm@^1.7.0:
   version "1.7.0"
   resolved "https://registry.yarnpkg.com/worker-farm/-/worker-farm-1.7.0.tgz#26a94c5391bbca926152002f69b84a4bf772e5a8"
@@ -6194,7 +5930,7 @@ y18n@^4.0.0:
   resolved "https://registry.yarnpkg.com/y18n/-/y18n-4.0.0.tgz#95ef94f85ecc81d007c264e190a120f0a3c8566b"
   integrity sha512-r9S/ZyXu/Xu9q1tYlpsLIsa3EeLXXk0VwlxqTcFRfg9EhMW+17kbt9G0NrgCmhGb5vT2hyhJZLfDGx+7+5Uj/w==
 
-yallist@^3.0.0, yallist@^3.0.2, yallist@^3.0.3:
+yallist@^3.0.2:
   version "3.1.1"
   resolved "https://registry.yarnpkg.com/yallist/-/yallist-3.1.1.tgz#dbb7daf9bfd8bac9ab45ebf602b8cbad0d5d08fd"
   integrity sha512-a4UGQaWPH59mOXUYnAG2ewncQS4i4F43Tv3JoAM+s2VDAmS9NsK8GpDMLrCHPksFT7h3K6TOoUNn2pb7RoXx4g==
diff --git a/packages/now-cli/test/dev/fixtures/27-zero-config-env/package.json b/packages/now-cli/test/dev/fixtures/27-zero-config-env/package.json
index 73b9a9b98..b1b562898 100644
--- a/packages/now-cli/test/dev/fixtures/27-zero-config-env/package.json
+++ b/packages/now-cli/test/dev/fixtures/27-zero-config-env/package.json
@@ -1,6 +1,6 @@
 {
   "private": true,
   "scripts": {
-    "build": "mkdir public && echo $FOO > public/index.html"
+    "build": "mkdir -p public && echo $FOO > public/index.html"
   }
 }
diff --git a/packages/now-cli/test/dev/fixtures/public-and-api/api/date.js b/packages/now-cli/test/dev/fixtures/public-and-api/api/date.js
index f08b8c196..c279c7f4c 100644
--- a/packages/now-cli/test/dev/fixtures/public-and-api/api/date.js
+++ b/packages/now-cli/test/dev/fixtures/public-and-api/api/date.js
@@ -1,3 +1,3 @@
-export default (_req, res) => {
+module.exports = (_req, res) => {
   res.end('current date: ' + new Date().toISOString());
 };
diff --git a/packages/now-cli/test/dev/fixtures/public-and-api/api/rand.js b/packages/now-cli/test/dev/fixtures/public-and-api/api/rand.js
index 47f067b12..dab352f96 100644
--- a/packages/now-cli/test/dev/fixtures/public-and-api/api/rand.js
+++ b/packages/now-cli/test/dev/fixtures/public-and-api/api/rand.js
@@ -1,3 +1,3 @@
-export default (_req, res) => {
+module.exports = (_req, res) => {
   res.end('random number: ' + Math.random());
 };
diff --git a/packages/now-cli/test/dev/integration.js b/packages/now-cli/test/dev/integration.js
index 628edc83c..6c5d7c791 100644
--- a/packages/now-cli/test/dev/integration.js
+++ b/packages/now-cli/test/dev/integration.js
@@ -110,7 +110,10 @@ async function exec(directory, args = []) {
 
 async function runNpmInstall(fixturePath) {
   if (await fs.exists(join(fixturePath, 'package.json'))) {
-    return execa('yarn', ['install'], { cwd: fixturePath, shell: true });
+    await execa('yarn', ['install'], {
+      cwd: fixturePath,
+      shell: true,
+    });
   }
 }
 
@@ -282,6 +285,9 @@ function testFixtureStdio(
         env,
       });
 
+      dev.stdout.pipe(process.stdout);
+      dev.stderr.pipe(process.stderr);
+
       dev.stdout.on('data', data => {
         stdoutList.push(data);
       });
diff --git a/packages/now-node/build.sh b/packages/now-node/build.sh
index 241220148..dd8dc18bb 100755
--- a/packages/now-node/build.sh
+++ b/packages/now-node/build.sh
@@ -30,14 +30,6 @@ ncc build ../../node_modules/source-map-support/register -e @vercel/build-utils
 mv dist/source-map-support/index.js dist/source-map-support.js
 rm -rf dist/source-map-support
 
-# build typescript
-ncc build ../../node_modules/typescript/lib/typescript -e @vercel/build-utils -e @now/build-utils -o dist/typescript
-mv dist/typescript/index.js dist/typescript.js
-mkdir -p dist/typescript/lib
-mv dist/typescript/typescript/lib/*.js dist/typescript/lib/
-mv dist/typescript/typescript/lib/*.d.ts dist/typescript/lib/
-rm -r dist/typescript/typescript
-
-ncc build src/index.ts -e @vercel/build-utils -e @now/build-utils -o dist/main
+ncc build src/index.ts -e @vercel/build-utils -e @now/build-utils -e typescript -o dist/main
 mv dist/main/index.js dist/index.js
 rm -rf dist/main
diff --git a/packages/now-node/package.json b/packages/now-node/package.json
index bbb43d2c3..ecc782a21 100644
--- a/packages/now-node/package.json
+++ b/packages/now-node/package.json
@@ -19,11 +19,14 @@
     "dist"
   ],
   "dependencies": {
-    "@types/node": "*"
+    "@types/node": "*",
+    "ts-node": "8.9.1",
+    "typescript": "3.8.3"
   },
   "devDependencies": {
     "@babel/core": "7.5.0",
     "@babel/plugin-transform-modules-commonjs": "7.5.0",
+    "@tootallnate/once": "1.1.2",
     "@types/aws-lambda": "8.10.19",
     "@types/content-type": "1.1.3",
     "@types/cookie": "0.3.3",
@@ -36,7 +39,6 @@
     "etag": "1.8.1",
     "node-fetch": "2.6.0",
     "source-map-support": "0.5.12",
-    "test-listen": "1.1.0",
-    "typescript": "3.5.2"
+    "test-listen": "1.1.0"
   }
 }
diff --git a/packages/now-node/src/dev-server.ts b/packages/now-node/src/dev-server.ts
new file mode 100644
index 000000000..d009f97d2
--- /dev/null
+++ b/packages/now-node/src/dev-server.ts
@@ -0,0 +1,75 @@
+import { register } from 'ts-node';
+
+// Use the project's version of TypeScript if available,
+// otherwise fall back to using the copy that `@now/node` uses.
+let compiler: string;
+try {
+  compiler = require.resolve('typescript', {
+    paths: [process.cwd(), __dirname],
+  });
+} catch (e) {
+  compiler = 'typescript';
+}
+
+register({
+  compiler,
+  compilerOptions: {
+    allowJs: true,
+    esModuleInterop: true,
+    jsx: 'react',
+  },
+  transpileOnly: true,
+});
+
+import http from 'http';
+import path from 'path';
+import { createServerWithHelpers } from './helpers';
+
+function listen(
+  server: http.Server,
+  port: number,
+  host: string
+): Promise<void> {
+  return new Promise(resolve => {
+    server.listen(port, host, () => {
+      resolve();
+    });
+  });
+}
+
+async function main() {
+  const entrypoint = process.env.NOW_DEV_ENTRYPOINT;
+  delete process.env.NOW_DEV_ENTRYPOINT;
+
+  if (!entrypoint) {
+    throw new Error('`NOW_DEV_ENTRYPOINT` must be defined');
+  }
+
+  const config = JSON.parse(process.env.NOW_DEV_CONFIG || '{}');
+  delete process.env.NOW_DEV_CONFIG;
+
+  const shouldAddHelpers = !(
+    config.helpers === false || process.env.NODEJS_HELPERS === '0'
+  );
+
+  const entrypointPath = path.join(process.cwd(), entrypoint);
+  const handler = await import(entrypointPath);
+
+  const server = shouldAddHelpers
+    ? createServerWithHelpers(handler.default)
+    : http.createServer(handler.default);
+
+  await listen(server, 0, '127.0.0.1');
+
+  const address = server.address();
+  if (typeof process.send === 'function') {
+    process.send(address);
+  } else {
+    console.log('Dev server listening:', address);
+  }
+}
+
+main().catch(err => {
+  console.error(err);
+  process.exit(1);
+});
diff --git a/packages/now-node/src/helpers.ts b/packages/now-node/src/helpers.ts
index d708b94be..a18c421ef 100644
--- a/packages/now-node/src/helpers.ts
+++ b/packages/now-node/src/helpers.ts
@@ -6,6 +6,7 @@ import {
   NowRequestBody,
 } from './types';
 import { Server } from 'http';
+import { Readable } from 'stream';
 import { Bridge } from './bridge';
 
 function getBodyParser(req: NowRequest, body: Buffer) {
@@ -81,6 +82,7 @@ function setCharset(type: string, charset: string) {
   return format(parsed);
 }
 
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
 function createETag(body: any, encoding: 'utf8' | undefined) {
   // eslint-disable-next-line @typescript-eslint/no-var-requires
   const etag = require('etag');
@@ -88,6 +90,7 @@ function createETag(body: any, encoding: 'utf8' | undefined) {
   return etag(buf, { weak: true });
 }
 
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
 function send(req: NowRequest, res: NowResponse, body: any): NowResponse {
   let chunk: unknown = body;
   let encoding: 'utf8' | undefined;
@@ -185,6 +188,7 @@ function send(req: NowRequest, res: NowResponse, body: any): NowResponse {
   return res;
 }
 
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
 function json(req: NowRequest, res: NowResponse, jsonBody: any): NowResponse {
   const body = JSON.stringify(jsonBody);
 
@@ -233,9 +237,24 @@ function setLazyProp<T>(req: NowRequest, prop: string, getter: () => T) {
   });
 }
 
+export function rawBody(readable: Readable): Promise<Buffer> {
+  return new Promise((resolve, reject) => {
+    let bytes = 0;
+    const chunks: Buffer[] = [];
+    readable.on('error', reject);
+    readable.on('data', chunk => {
+      chunks.push(chunk);
+      bytes += chunk.length;
+    });
+    readable.on('end', () => {
+      resolve(Buffer.concat(chunks, bytes));
+    });
+  });
+}
+
 export function createServerWithHelpers(
-  listener: (req: NowRequest, res: NowResponse) => void | Promise<void>,
-  bridge: Bridge
+  handler: (req: NowRequest, res: NowResponse) => void | Promise<void>,
+  bridge?: Bridge
 ) {
   const server = new Server(async (_req, _res) => {
     const req = _req as NowRequest;
@@ -247,21 +266,23 @@ export function createServerWithHelpers(
       // don't expose this header to the client
       delete req.headers['x-now-bridge-request-id'];
 
-      if (typeof reqId !== 'string') {
-        throw new ApiError(500, 'Internal Server Error');
+      let body: Buffer;
+      if (typeof reqId === 'string' && bridge) {
+        const event = bridge.consumeEvent(reqId);
+        body = event.body;
+      } else {
+        body = await rawBody(req);
       }
 
-      const event = bridge.consumeEvent(reqId);
-
       setLazyProp<NowRequestCookies>(req, 'cookies', getCookieParser(req));
       setLazyProp<NowRequestQuery>(req, 'query', getQueryParser(req));
-      setLazyProp<NowRequestBody>(req, 'body', getBodyParser(req, event.body));
+      setLazyProp<NowRequestBody>(req, 'body', getBodyParser(req, body));
 
       res.status = statusCode => status(res, statusCode);
       res.send = body => send(req, res, body);
       res.json = jsonBody => json(req, res, jsonBody);
 
-      await listener(req, res);
+      await handler(req, res);
     } catch (err) {
       if (err instanceof ApiError) {
         sendError(res, err.statusCode, err.message);
diff --git a/packages/now-node/src/index.ts b/packages/now-node/src/index.ts
index 96e4e7ca8..807fff4f3 100644
--- a/packages/now-node/src/index.ts
+++ b/packages/now-node/src/index.ts
@@ -1,12 +1,22 @@
+import { fork, spawn } from 'child_process';
+import {
+  readFileSync,
+  lstatSync,
+  readlinkSync,
+  statSync,
+  promises as fsp,
+} from 'fs';
 import {
   basename,
   dirname,
+  extname,
   join,
   relative,
   resolve,
   sep,
   parse as parsePath,
 } from 'path';
+import once from '@tootallnate/once';
 import nodeFileTrace from '@zeit/node-file-trace';
 import buildUtils from './build-utils';
 import {
@@ -16,6 +26,8 @@ import {
   PrepareCacheOptions,
   BuildOptions,
   Config,
+  StartDevServerOptions,
+  StartDevServerResult,
 } from '@vercel/build-utils';
 const {
   glob,
@@ -30,12 +42,13 @@ const {
   shouldServe,
   debug,
   isSymbolicLink,
+  walkParentDirs,
 } = buildUtils;
+import { makeNowLauncher, makeAwsLauncher } from './launcher';
+import { Register, register } from './typescript';
+
 export { shouldServe };
 export { NowRequest, NowResponse } from './types';
-import { makeNowLauncher, makeAwsLauncher } from './launcher';
-import { readFileSync, lstatSync, readlinkSync, statSync } from 'fs';
-import { Register, register } from './typescript';
 
 interface CompilerConfig {
   debug?: boolean;
@@ -51,6 +64,19 @@ interface DownloadOptions {
   meta: Meta;
 }
 
+interface PortInfo {
+  port: number;
+}
+
+function isPortInfo(v: any): v is PortInfo {
+  return v && typeof v.port === 'number';
+}
+
+const tscPath = resolve(
+  dirname(require.resolve(eval('"typescript"'))),
+  '../bin/tsc'
+);
+
 // eslint-disable-next-line no-useless-escape
 const libPathRegEx = /^node_modules|[\/\\]node_modules[\/\\]/;
 
@@ -317,6 +343,7 @@ export async function build({
   const shouldAddHelpers = !(
     config.helpers === false || process.env.NODEJS_HELPERS === '0'
   );
+
   const awsLambdaHandler = getAWSLambdaHandler(entrypoint, config);
 
   const {
@@ -396,3 +423,89 @@ export async function prepareCache({
   const cache = await glob('node_modules/**', workPath);
   return cache;
 }
+
+export async function startDevServer(
+  opts: StartDevServerOptions
+): Promise<StartDevServerResult> {
+  const { entrypoint, workPath, config, env } = opts;
+  const devServerPath = join(__dirname, 'dev-server.js');
+  const child = fork(devServerPath, [], {
+    cwd: workPath,
+    env: {
+      ...process.env,
+      ...env,
+      NOW_DEV_ENTRYPOINT: entrypoint,
+      NOW_DEV_CONFIG: JSON.stringify(config),
+    },
+  });
+
+  const { pid } = child;
+  const onMessage = once<{ port: number }>(child, 'message');
+  const onExit = once.spread<[number, string | null]>(child, 'exit');
+  const result = await Promise.race([onMessage, onExit]);
+  onExit.cancel();
+  onMessage.cancel();
+
+  if (isPortInfo(result)) {
+    // "message" event
+
+    const ext = extname(entrypoint);
+    if (ext === '.ts' || ext === '.tsx') {
+      // Invoke `tsc --noEmit` asynchronously in the background, so
+      // that the HTTP request is not blocked by the type checking.
+      doTypeCheck(opts).catch((err: Error) => {
+        console.error('Type check for %j failed:', entrypoint, err);
+      });
+    }
+
+    return { port: result.port, pid };
+  } else {
+    // "exit" event
+    throw new Error(
+      `Failed to start dev server for "${entrypoint}" (code=${result[0]}, signal=${result[1]})`
+    );
+  }
+}
+
+async function doTypeCheck({
+  entrypoint,
+  workPath,
+}: StartDevServerOptions): Promise<void> {
+  // In order to type-check a single file, a temporary tsconfig
+  // file needs to be created that inherits from the base one :(
+  // See: https://stackoverflow.com/a/44748041/376773
+  const id = Math.random()
+    .toString(32)
+    .substring(2);
+  const tempConfigName = `.tsconfig-${id}.json`;
+  const projectTsConfig = await walkParentDirs({
+    base: workPath,
+    start: join(workPath, dirname(entrypoint)),
+    filename: 'tsconfig.json',
+  });
+  const tsconfig = {
+    extends: projectTsConfig || undefined,
+    include: [entrypoint],
+  };
+  await fsp.writeFile(tempConfigName, JSON.stringify(tsconfig));
+
+  const child = spawn(
+    process.execPath,
+    [
+      tscPath,
+      '--project',
+      tempConfigName,
+      '--noEmit',
+      '--allowJs',
+      '--esModuleInterop',
+      '--jsx',
+      'react',
+    ],
+    {
+      cwd: workPath,
+      stdio: 'inherit',
+    }
+  );
+  await once.spread<[number, string | null]>(child, 'exit');
+  await fsp.unlink(tempConfigName);
+}
diff --git a/packages/now-node/src/typescript.ts b/packages/now-node/src/typescript.ts
index 3254a219e..4abb6cc1c 100644
--- a/packages/now-node/src/typescript.ts
+++ b/packages/now-node/src/typescript.ts
@@ -157,7 +157,7 @@ export function register(opts: Options = {}): Register {
       paths: [options.project || cwd, nowNodeBase],
     });
   } catch (e) {
-    compiler = require.resolve(eval('"./typescript"'));
+    compiler = require.resolve(eval('"typescript"'));
   }
   //eslint-disable-next-line @typescript-eslint/no-var-requires
   const ts: typeof _ts = require(compiler);
diff --git a/yarn.lock b/yarn.lock
index a42d79ce0..12f75359c 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1422,10 +1422,10 @@
   dependencies:
     defer-to-connect "^1.0.1"
 
-"@tootallnate/once@1":
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/@tootallnate/once/-/once-1.0.0.tgz#9c13c2574c92d4503b005feca8f2e16cc1611506"
-  integrity sha512-KYyTT/T6ALPkIRd2Ge080X/BsXvy9O0hcWTtMWkPvwAwF99+vn6Dv4GzrFT/Nn1LePr+FFDbRXXlqmsy9lw2zA==
+"@tootallnate/once@1", "@tootallnate/once@1.1.2":
+  version "1.1.2"
+  resolved "https://registry.yarnpkg.com/@tootallnate/once/-/once-1.1.2.tgz#ccb91445360179a04e7fe6aff78c00ffc1eeaf82"
+  integrity sha512-RbzJvlNzmRq5c3O09UipeuXno4tA1FE6ikOjxZK0tuxVv3412l64l5t1W5pj4+rJq9vpkm/kwiR07aZXnsKPxw==
 
 "@types/ansi-escapes@3.0.0":
   version "3.0.0"
@@ -9963,6 +9963,14 @@ source-map-support@^0.5.12, source-map-support@^0.5.6:
     buffer-from "^1.0.0"
     source-map "^0.6.0"
 
+source-map-support@^0.5.17:
+  version "0.5.19"
+  resolved "https://registry.yarnpkg.com/source-map-support/-/source-map-support-0.5.19.tgz#a98b62f86dcaf4f67399648c085291ab9e8fed61"
+  integrity sha512-Wonm7zOCIJzBGQdB+thsPar0kYuCIzYvxZwlBa87yi/Mdjv7Tip2cyVbLj5o0cFPN4EVkuTwb3GDDyUx2DGnGw==
+  dependencies:
+    buffer-from "^1.0.0"
+    source-map "^0.6.0"
+
 source-map-url@^0.4.0:
   version "0.4.0"
   resolved "https://registry.yarnpkg.com/source-map-url/-/source-map-url-0.4.0.tgz#3e935d7ddd73631b97659956d55128e87b5084a3"
@@ -10775,6 +10783,17 @@ ts-node@8.3.0:
     source-map-support "^0.5.6"
     yn "^3.0.0"
 
+ts-node@8.9.1:
+  version "8.9.1"
+  resolved "https://registry.yarnpkg.com/ts-node/-/ts-node-8.9.1.tgz#2f857f46c47e91dcd28a14e052482eb14cfd65a5"
+  integrity sha512-yrq6ODsxEFTLz0R3BX2myf0WBCSQh9A+py8PBo1dCzWIOcvisbyH6akNKqDHMgXePF2kir5mm5JXJTH3OUJYOQ==
+  dependencies:
+    arg "^4.1.0"
+    diff "^4.0.1"
+    make-error "^1.1.1"
+    source-map-support "^0.5.17"
+    yn "3.1.1"
+
 tslib@^1.8.1, tslib@^1.9.0, tslib@^1.9.3:
   version "1.10.0"
   resolved "https://registry.yarnpkg.com/tslib/-/tslib-1.10.0.tgz#c3c19f95973fb0a62973fb09d90d961ee43e5c8a"
@@ -10858,6 +10877,11 @@ typescript@3.6.4:
   resolved "https://registry.yarnpkg.com/typescript/-/typescript-3.6.4.tgz#b18752bb3792bc1a0281335f7f6ebf1bbfc5b91d"
   integrity sha512-unoCll1+l+YK4i4F8f22TaNVPRHcD9PA3yCuZ8g5e0qGqlVlJ/8FSateOLLSagn+Yg5+ZwuPkL8LFUc0Jcvksg==
 
+typescript@3.8.3:
+  version "3.8.3"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-3.8.3.tgz#409eb8544ea0335711205869ec458ab109ee1061"
+  integrity sha512-MYlEfn5VrLNsgudQTVJeNaQFUAI7DkhnOjdpAp4T+ku1TfQClewlbSuTVHiA+8skNBgaf02TL/kLOvig4y3G8w==
+
 uglify-js@^3.1.4:
   version "3.7.3"
   resolved "https://registry.yarnpkg.com/uglify-js/-/uglify-js-3.7.3.tgz#f918fce9182f466d5140f24bb0ff35c2d32dcc6a"
@@ -11486,11 +11510,6 @@ yargs@^13.3.0:
     y18n "^4.0.0"
     yargs-parser "^13.1.1"
 
-yarn@1.22.0:
-  version "1.22.0"
-  resolved "https://registry.yarnpkg.com/yarn/-/yarn-1.22.0.tgz#acf82906e36bcccd1ccab1cfb73b87509667c881"
-  integrity sha512-KMHP/Jq53jZKTY9iTUt3dIVl/be6UPs2INo96+BnZHLKxYNTfwMmlgHTaMWyGZoO74RI4AIFvnWhYrXq2USJkg==
-
 yauzl-clone@^1.0.4:
   version "1.0.4"
   resolved "https://registry.yarnpkg.com/yauzl-clone/-/yauzl-clone-1.0.4.tgz#8bc6d293b17cc98802bbbed2e289d18e7697c96c"
@@ -11527,7 +11546,7 @@ yazl@2.4.3:
   dependencies:
     buffer-crc32 "~0.2.3"
 
-yn@^3.0.0:
+yn@3.1.1, yn@^3.0.0:
   version "3.1.1"
   resolved "https://registry.yarnpkg.com/yn/-/yn-3.1.1.tgz#1e87401a09d767c1d5eab26a6e4c185182d2eb50"
   integrity sha512-Ux4ygGWsu2c7isFWe8Yu1YluJmqVhxqK2cLXNQA5AcC3QfbGNpM7fu0Y8b/z16pXLnFxZYvWhd3fhBY9DLmC6Q==