diff --git a/packages/angular/cli/lib/config/schema.json b/packages/angular/cli/lib/config/schema.json
index c8e163d12103..fe0cdfea4ff6 100644
--- a/packages/angular/cli/lib/config/schema.json
+++ b/packages/angular/cli/lib/config/schema.json
@@ -970,12 +970,6 @@
               },
               "default": []
             },
-            "rebaseRootRelativeCssUrls": {
-              "description": "Change root relative URLs in stylesheets to include base HREF and deploy URL. Use only for compatibility and transition. The behavior of this option is non-standard and will be removed in the next major release.",
-              "type": "boolean",
-              "default": false,
-              "x-deprecated": true
-            },
             "webWorkerTsConfig": {
               "type": "string",
               "description": "TypeScript configuration for Web Worker modules."
diff --git a/packages/angular_devkit/build_angular/src/browser/schema.json b/packages/angular_devkit/build_angular/src/browser/schema.json
index 628b5dcd8dd8..70d7c8302036 100644
--- a/packages/angular_devkit/build_angular/src/browser/schema.json
+++ b/packages/angular_devkit/build_angular/src/browser/schema.json
@@ -348,12 +348,6 @@
       },
       "default": []
     },
-    "rebaseRootRelativeCssUrls": {
-      "description": "Change root relative URLs in stylesheets to include base HREF and deploy URL. Use only for compatibility and transition. The behavior of this option is non-standard and will be removed in the next major release.",
-      "type": "boolean",
-      "default": false,
-      "x-deprecated": true
-    },
     "webWorkerTsConfig": {
       "type": "string",
       "description": "TypeScript configuration for Web Worker modules."
diff --git a/packages/angular_devkit/build_angular/src/browser/specs/styles_spec.ts b/packages/angular_devkit/build_angular/src/browser/specs/styles_spec.ts
index 7da64970b00e..577ca5a55c41 100644
--- a/packages/angular_devkit/build_angular/src/browser/specs/styles_spec.ts
+++ b/packages/angular_devkit/build_angular/src/browser/specs/styles_spec.ts
@@ -354,7 +354,7 @@ describe('Browser Builder styles', () => {
   });
 
   // TODO: consider making this a unit test in the url processing plugins.
-  it(`supports baseHref/deployUrl in resource urls without rebaseRootRelativeCssUrls`, async () => {
+  it(`supports baseHref/deployUrl in resource urls`, async () => {
     // Use a large image for the relative ref so it cannot be inlined.
     host.copyFile('src/spectrum.png', './src/assets/global-img-relative.png');
     host.copyFile('src/spectrum.png', './src/assets/component-img-relative.png');
@@ -458,118 +458,6 @@ describe('Browser Builder styles', () => {
     expect(main).toContain(`url('/assets/component-img-absolute.svg')`);
   }, 90000);
 
-  it(`supports baseHref/deployUrl in resource urls with rebaseRootRelativeCssUrls`, async () => {
-    // Use a large image for the relative ref so it cannot be inlined.
-    host.copyFile('src/spectrum.png', './src/assets/global-img-relative.png');
-    host.copyFile('src/spectrum.png', './src/assets/component-img-relative.png');
-    host.writeMultipleFiles({
-      'src/styles.css': `
-        h1 { background: url('/assets/global-img-absolute.svg'); }
-        h2 { background: url('./assets/global-img-relative.png'); }
-      `,
-      'src/app/app.component.css': `
-        h3 { background: url('/assets/component-img-absolute.svg'); }
-        h4 { background: url('../assets/component-img-relative.png'); }
-      `,
-      'src/assets/global-img-absolute.svg': imgSvg,
-      'src/assets/component-img-absolute.svg': imgSvg,
-    });
-
-    // Check base paths are correctly generated.
-    const overrides = {
-      extractCss: true,
-      rebaseRootRelativeCssUrls: true,
-    };
-    let { files } = await browserBuild(architect, host, target, {
-      ...overrides,
-      aot: true,
-    });
-
-    let styles = await files['styles.css'];
-    let main = await files['main.js'];
-    expect(styles).toContain(`url('/assets/global-img-absolute.svg')`);
-    expect(styles).toContain(`url('global-img-relative.png')`);
-    expect(main).toContain(`url('/assets/component-img-absolute.svg')`);
-    expect(main).toContain(`url('component-img-relative.png')`);
-    expect(host.scopedSync().exists(normalize('dist/assets/global-img-absolute.svg'))).toBe(true);
-    expect(host.scopedSync().exists(normalize('dist/global-img-relative.png'))).toBe(true);
-    expect(host.scopedSync().exists(normalize('dist/assets/component-img-absolute.svg'))).toBe(
-      true,
-    );
-    expect(host.scopedSync().exists(normalize('dist/component-img-relative.png'))).toBe(true);
-
-    // Check urls with deploy-url scheme are used as is.
-    files = (await browserBuild(architect, host, target, {
-      ...overrides,
-      baseHref: '/base/',
-      deployUrl: 'http://deploy.url/',
-    })).files;
-
-    styles = await files['styles.css'];
-    main = await files['main.js'];
-    expect(styles).toContain(`url('http://deploy.url/assets/global-img-absolute.svg')`);
-    expect(main).toContain(`url('http://deploy.url/assets/component-img-absolute.svg')`);
-
-    // Check urls with base-href scheme are used as is (with deploy-url).
-    files = (await browserBuild(architect, host, target, {
-      ...overrides,
-      baseHref: 'http://base.url/',
-      deployUrl: 'deploy/',
-    })).files;
-
-    styles = await files['styles.css'];
-    main = await files['main.js'];
-    expect(styles).toContain(`url('http://base.url/deploy/assets/global-img-absolute.svg')`);
-    expect(main).toContain(`url('http://base.url/deploy/assets/component-img-absolute.svg')`);
-
-    // Check urls with deploy-url and base-href scheme only use deploy-url.
-    files = (await browserBuild(architect, host, target, {
-      ...overrides,
-      baseHref: 'http://base.url/',
-      deployUrl: 'http://deploy.url/',
-    })).files;
-
-    styles = await files['styles.css'];
-    main = await files['main.js'];
-    expect(styles).toContain(`url('http://deploy.url/assets/global-img-absolute.svg')`);
-    expect(main).toContain(`url('http://deploy.url/assets/component-img-absolute.svg')`);
-
-    // Check with schemeless base-href and deploy-url flags.
-    files = (await browserBuild(architect, host, target, {
-      ...overrides,
-      baseHref: '/base/',
-      deployUrl: 'deploy/',
-    })).files;
-
-    styles = await files['styles.css'];
-    main = await files['main.js'];
-    expect(styles).toContain(`url('/base/deploy/assets/global-img-absolute.svg')`);
-    expect(main).toContain(`url('/base/deploy/assets/component-img-absolute.svg')`);
-
-    // Check with identical base-href and deploy-url flags.
-    files = (await browserBuild(architect, host, target, {
-      ...overrides,
-      baseHref: '/base/',
-      deployUrl: '/base/',
-    })).files;
-
-    styles = await files['styles.css'];
-    main = await files['main.js'];
-    expect(styles).toContain(`url('/base/assets/global-img-absolute.svg')`);
-    expect(main).toContain(`url('/base/assets/component-img-absolute.svg')`);
-
-    // Check with only base-href flag.
-    files = (await browserBuild(architect, host, target, {
-      ...overrides,
-      baseHref: '/base/',
-    })).files;
-
-    styles = await files['styles.css'];
-    main = await files['main.js'];
-    expect(styles).toContain(`url('/base/assets/global-img-absolute.svg')`);
-    expect(main).toContain(`url('/base/assets/component-img-absolute.svg')`);
-  }, 90000);
-
   it(`supports bootstrap@4 with full path`, async () => {
     const bootstrapPath = dirname(require.resolve('bootstrap/package.json'));
 
diff --git a/packages/angular_devkit/build_angular/src/utils/build-options.ts b/packages/angular_devkit/build_angular/src/utils/build-options.ts
index 386c3a89436c..0063bf0775e4 100644
--- a/packages/angular_devkit/build_angular/src/utils/build-options.ts
+++ b/packages/angular_devkit/build_angular/src/utils/build-options.ts
@@ -75,8 +75,6 @@ export interface BuildOptions {
   lazyModules: string[];
   platform?: 'browser' | 'server';
   fileReplacements: NormalizedFileReplacement[];
-  /** @deprecated use only for compatibility in 8.x; will be removed in 9.0 */
-  rebaseRootRelativeCssUrls?: boolean;
 
   experimentalRollupPass?: boolean;
   allowedCommonJsDependencies?: string[];
diff --git a/packages/angular_devkit/build_angular/src/webpack/configs/styles.ts b/packages/angular_devkit/build_angular/src/webpack/configs/styles.ts
index 002c7ecb699b..835712ba23bf 100644
--- a/packages/angular_devkit/build_angular/src/webpack/configs/styles.ts
+++ b/packages/angular_devkit/build_angular/src/webpack/configs/styles.ts
@@ -184,7 +184,6 @@ export function getStylesConfig(wco: WebpackConfigOptions) {
           deployUrl: buildOptions.deployUrl,
           resourcesOutputPath: buildOptions.resourcesOutputPath,
           loader,
-          rebaseRootRelative: buildOptions.rebaseRootRelativeCssUrls,
           filename: `[name]${hashFormat.file}.[ext]`,
           emitFile: buildOptions.platform !== 'server',
           extracted,
diff --git a/packages/angular_devkit/build_angular/src/webpack/plugins/postcss-cli-resources.ts b/packages/angular_devkit/build_angular/src/webpack/plugins/postcss-cli-resources.ts
index 3fbda764a394..db6af3669628 100644
--- a/packages/angular_devkit/build_angular/src/webpack/plugins/postcss-cli-resources.ts
+++ b/packages/angular_devkit/build_angular/src/webpack/plugins/postcss-cli-resources.ts
@@ -57,22 +57,19 @@ export default postcss.plugin('postcss-cli-resources', (options: PostcssCliResou
     deployUrl = '',
     baseHref = '',
     resourcesOutputPath = '',
-    rebaseRootRelative = false,
     filename,
     loader,
     emitFile,
     extracted,
   } = options;
 
-  const dedupeSlashes = (url: string) => url.replace(/\/\/+/g, '/');
-
   const process = async (inputUrl: string, context: string, resourceCache: Map<string, string>) => {
     // If root-relative, absolute or protocol relative url, leave as is
     if (/^((?:\w+:)?\/\/|data:|chrome:|#)/.test(inputUrl)) {
       return inputUrl;
     }
 
-    if (!rebaseRootRelative && /^\//.test(inputUrl)) {
+    if (/^\//.test(inputUrl)) {
       return inputUrl;
     }
 
@@ -88,24 +85,6 @@ export default postcss.plugin('postcss-cli-resources', (options: PostcssCliResou
       return cachedUrl;
     }
 
-    if (rebaseRootRelative && inputUrl.startsWith('/')) {
-      let outputUrl = '';
-      if (deployUrl.match(/:\/\//) || deployUrl.startsWith('/')) {
-        // If deployUrl is absolute or root relative, ignore baseHref & use deployUrl as is.
-        outputUrl = `${deployUrl.replace(/\/$/, '')}${inputUrl}`;
-      } else if (baseHref.match(/:\/\//)) {
-        // If baseHref contains a scheme, include it as is.
-        outputUrl = baseHref.replace(/\/$/, '') + dedupeSlashes(`/${deployUrl}/${inputUrl}`);
-      } else {
-        // Join together base-href, deploy-url and the original URL.
-        outputUrl = dedupeSlashes(`/${baseHref}/${deployUrl}/${inputUrl}`);
-      }
-
-      resourceCache.set(cacheKey, outputUrl);
-
-      return outputUrl;
-    }
-
     if (inputUrl.startsWith('~')) {
       inputUrl = inputUrl.substr(1);
     }