angular
diff --git a/packages/angular_devkit/build_angular/src/builders/browser/specs/vendor-source-map_spec.ts b/packages/angular_devkit/build_angular/src/builders/browser/specs/vendor-source-map_spec.ts
@@ -10,6 +10,10 @@ import { Architect } from '@angular-devkit/architect';
 import * as path from 'path';
 import { browserBuild, createArchitect, host } from '../../../testing/test-utils';
 
+// Following the naming conventions from
+// https://sourcemaps.info/spec.html#h.ghqpj1ytqjbm
+const IGNORE_LIST = 'x_google_ignoreList';
+
 describe('Browser Builder external source map', () => {
   const target = { project: 'app', target: 'build' };
   let architect: Architect;
@@ -50,3 +54,70 @@ describe('Browser Builder external source map', () => {
     expect(hasTsSourcePaths).toBe(false, `vendor.js.map not should have '.ts' extentions`);
   });
 });
+
+describe('Identifying third-party code in source maps', () => {
+  interface SourceMap {
+    sources: string[];
+    [IGNORE_LIST]: number[];
+  }
+
+  const target = { project: 'app', target: 'build' };
+  let architect: Architect;
+
+  beforeEach(async () => {
+    await host.initialize().toPromise();
+    architect = (await createArchitect(host.root())).architect;
+  });
+  afterEach(async () => host.restore().toPromise());
+
+  it('specifies which sources are third party when vendor processing is disabled', async () => {
+    const overrides = {
+      sourceMap: {
+        scripts: true,
+        vendor: false,
+      },
+    };
+
+    const { files } = await browserBuild(architect, host, target, overrides);
+    const mainMap: SourceMap = JSON.parse(await files['main.js.map']);
+    const polyfillsMap: SourceMap = JSON.parse(await files['polyfills.js.map']);
+    const runtimeMap: SourceMap = JSON.parse(await files['runtime.js.map']);
+    const vendorMap: SourceMap = JSON.parse(await files['vendor.js.map']);
+
+    expect(mainMap[IGNORE_LIST]).not.toBeUndefined();
+    expect(polyfillsMap[IGNORE_LIST]).not.toBeUndefined();
+    expect(runtimeMap[IGNORE_LIST]).not.toBeUndefined();
+    expect(vendorMap[IGNORE_LIST]).not.toBeUndefined();
+
+    expect(mainMap[IGNORE_LIST].length).toEqual(0);
+    expect(polyfillsMap[IGNORE_LIST].length).not.toEqual(0);
+    expect(runtimeMap[IGNORE_LIST].length).not.toEqual(0);
+    expect(vendorMap[IGNORE_LIST].length).not.toEqual(0);
+
+    const thirdPartyInMain = mainMap.sources.some((s) => s.includes('node_modules'));
+    const thirdPartyInPolyfills = polyfillsMap.sources.some((s) => s.includes('node_modules'));
+    const thirdPartyInRuntime = runtimeMap.sources.some((s) => s.includes('webpack'));
+    const thirdPartyInVendor = vendorMap.sources.some((s) => s.includes('node_modules'));
+    expect(thirdPartyInMain).toBe(false, `main.js.map should not include any node modules`);
+    expect(thirdPartyInPolyfills).toBe(true, `polyfills.js.map should include some node modules`);
+    expect(thirdPartyInRuntime).toBe(true, `runtime.js.map should include some webpack code`);
+    expect(thirdPartyInVendor).toBe(true, `vendor.js.map should include some node modules`);
+
+    // All sources in the main map are first-party.
+    expect(mainMap.sources.filter((_, i) => !mainMap[IGNORE_LIST].includes(i))).toEqual([
+      './src/app/app.component.ts',
+      './src/app/app.module.ts',
+      './src/environments/environment.ts',
+      './src/main.ts',
+    ]);
+
+    // Only some sources in the polyfills map are first-party.
+    expect(polyfillsMap.sources.filter((_, i) => !polyfillsMap[IGNORE_LIST].includes(i))).toEqual([
+      './src/polyfills.ts',
+    ]);
+
+    // None of the sources in the runtime and vendor maps are first-party.
+    expect(runtimeMap.sources.filter((_, i) => !runtimeMap[IGNORE_LIST].includes(i))).toEqual([]);
+    expect(vendorMap.sources.filter((_, i) => !vendorMap[IGNORE_LIST].includes(i))).toEqual([]);
+  });
+});
diff --git a/packages/angular_devkit/build_angular/src/webpack/configs/common.ts b/packages/angular_devkit/build_angular/src/webpack/configs/common.ts
@@ -29,6 +29,7 @@ import {
   JsonStatsPlugin,
   ScriptsWebpackPlugin,
 } from '../plugins';
+import { DevToolsIgnorePlugin } from '../plugins/devtools-ignore-plugin';
 import { NamedChunksPlugin } from '../plugins/named-chunks-plugin';
 import { ProgressPlugin } from '../plugins/progress-plugin';
 import { TransferSizePlugin } from '../plugins/transfer-size-plugin';
@@ -45,6 +46,8 @@ import {
   globalScriptsByBundleName,
 } from '../utils/helpers';
 
+const VENDORS_TEST = /[\\/]node_modules[\\/]/;
+
 // eslint-disable-next-line max-lines-per-function
 export async function getCommonConfig(wco: WebpackConfigOptions): Promise<Configuration> {
   const {
@@ -190,6 +193,8 @@ export async function getCommonConfig(wco: WebpackConfigOptions): Promise<Config
       include.push(/css$/);
     }
 
+    extraPlugins.push(new DevToolsIgnorePlugin());
+
     extraPlugins.push(
       new SourceMapDevToolPlugin({
         filename: '[file].map',
@@ -434,7 +439,7 @@ export async function getCommonConfig(wco: WebpackConfigOptions): Promise<Config
             name: 'vendor',
             chunks: (chunk) => chunk.name === 'main',
             enforce: true,
-            test: /[\\/]node_modules[\\/]/,
+            test: VENDORS_TEST,
           },
         },
       },

diff --git a/packages/angular_devkit/build_angular/src/webpack/plugins/devtools-ignore-plugin.ts b/packages/angular_devkit/build_angular/src/webpack/plugins/devtools-ignore-plugin.ts
@@ -0,0 +1,69 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import { Compilation, Compiler } from 'webpack';
+
+// Following the naming conventions from
+// https://sourcemaps.info/spec.html#h.ghqpj1ytqjbm
+const IGNORE_LIST = 'x_google_ignoreList';
+
+const PLUGIN_NAME = 'devtools-ignore-plugin';
+
+interface SourceMap {
+  sources: string[];
+  [IGNORE_LIST]: number[];
+}
+
+/**
+ * This plugin adds a field to source maps that identifies which sources are
+ * vendored or runtime-injected (aka third-party) sources. These are consumed by
+ * Chrome DevTools to automatically ignore-list sources.
+ */
+export class DevToolsIgnorePlugin {
+  apply(compiler: Compiler) {
+    const { RawSource } = compiler.webpack.sources;
+
+    compiler.hooks.compilation.tap(PLUGIN_NAME, (compilation) => {
+      compilation.hooks.processAssets.tap(
+        {
+          name: PLUGIN_NAME,
+          stage: Compilation.PROCESS_ASSETS_STAGE_DEV_TOOLING,
+          additionalAssets: true,
+        },
+        (assets) => {
+          for (const [name, asset] of Object.entries(assets)) {
+            // Instead of using `asset.map()` to fetch the source maps from
+            // SourceMapSource assets, process them directly as a RawSource.
+            // This is because `.map()` is slow and can take several seconds.
+            if (!name.endsWith('.map')) {
+              // Ignore non source map files.
+              continue;
+            }
+
+            const mapContent = asset.source().toString();
+            if (!mapContent) {
+              continue;
+            }
+
+            const map = JSON.parse(mapContent) as SourceMap;
+            const ignoreList = [];
+
+            for (const [index, path] of map.sources.entries()) {
+              if (path.includes('/node_modules/') || path.startsWith('webpack/')) {
+                ignoreList.push(index);
+              }
+            }
+
+            map[IGNORE_LIST] = ignoreList;
+            compilation.updateAsset(name, new RawSource(JSON.stringify(map)));
+          }
+        },
+      );
+    });
+  }
+}