diff --git a/packages/@angular/cli/models/webpack-configs/common.ts b/packages/@angular/cli/models/webpack-configs/common.ts
index 3bb619876df6..4a75f21e7703 100644
--- a/packages/@angular/cli/models/webpack-configs/common.ts
+++ b/packages/@angular/cli/models/webpack-configs/common.ts
@@ -10,7 +10,6 @@ const autoprefixer = require('autoprefixer');
 const ProgressPlugin = require('webpack/lib/ProgressPlugin');
 const HtmlWebpackPlugin = require('html-webpack-plugin');
 const ExtractTextPlugin = require('extract-text-webpack-plugin');
-const SilentError = require('silent-error');
 
 /**
  * Enumerate loaders and their dependencies from this file to let the dependency validator
@@ -71,25 +70,6 @@ export function getCommonConfig(wco: WebpackConfigOptions) {
     }));
   }
 
-  // process environment file replacement
-  if (appConfig.environments) {
-    if (!('source' in appConfig.environments)) {
-      throw new SilentError(`Environment configuration does not contain "source" entry.`);
-    }
-    if (!(buildOptions.environment in appConfig.environments)) {
-      throw new SilentError(`Environment "${buildOptions.environment}" does not exist.`);
-    }
-
-    extraPlugins.push(new webpack.NormalModuleReplacementPlugin(
-      // This plugin is responsible for swapping the environment files.
-      // Since it takes a RegExp as first parameter, we need to escape the path.
-      // See https://webpack.github.io/docs/list-of-plugins.html#normalmodulereplacementplugin
-      new RegExp(path.resolve(appRoot, appConfig.environments['source'])
-        .replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, '\\$&')),
-      path.resolve(appRoot, appConfig.environments[buildOptions.environment])
-    ));
-  }
-
   // process asset entries
   if (appConfig.assets) {
     extraPlugins.push(new GlobCopyWebpackPlugin({
diff --git a/packages/@angular/cli/models/webpack-configs/typescript.ts b/packages/@angular/cli/models/webpack-configs/typescript.ts
index cba5a918b719..8f3b241d196b 100644
--- a/packages/@angular/cli/models/webpack-configs/typescript.ts
+++ b/packages/@angular/cli/models/webpack-configs/typescript.ts
@@ -1,7 +1,10 @@
+import * as fs from 'fs';
 import * as path from 'path';
-import {AotPlugin} from '@ngtools/webpack';
+import {AotPlugin, AotPluginOptions} from '@ngtools/webpack';
 import { WebpackConfigOptions } from '../webpack-config';
 
+const SilentError = require('silent-error');
+
 
 const g: any = global;
 const webpackLoader: string = g['angularCliIsLocal']
@@ -9,6 +12,39 @@ const webpackLoader: string = g['angularCliIsLocal']
   : '@ngtools/webpack';
 
 
+function _createAotPlugin(wco: WebpackConfigOptions, options: any) {
+  const { appConfig, projectRoot, buildOptions } = wco;
+
+  // Read the environment, and set it in the compiler host.
+  let hostOverrideFileSystem: any = {};
+  // process environment file replacement
+  if (appConfig.environments) {
+    if (!('source' in appConfig.environments)) {
+      throw new SilentError(`Environment configuration does not contain "source" entry.`);
+    }
+    if (!(buildOptions.environment in appConfig.environments)) {
+      throw new SilentError(`Environment "${buildOptions.environment}" does not exist.`);
+    }
+
+    const appRoot = path.resolve(projectRoot, appConfig.root);
+    const sourcePath = appConfig.environments['source'];
+    const envFile = appConfig.environments[buildOptions.environment];
+    const environmentContent = fs.readFileSync(path.join(appRoot, envFile)).toString();
+
+    hostOverrideFileSystem = { [path.join(appRoot, sourcePath)]: environmentContent };
+  }
+
+  return new AotPlugin(Object.assign({}, {
+      tsConfigPath: path.resolve(projectRoot, appConfig.root, appConfig.tsconfig),
+      mainPath: path.join(projectRoot, appConfig.root, appConfig.main),
+      i18nFile: buildOptions.i18nFile,
+      i18nFormat: buildOptions.i18nFormat,
+      locale: buildOptions.locale,
+      hostOverrideFileSystem
+    }, options));
+}
+
+
 export const getNonAotConfig = function(wco: WebpackConfigOptions) {
   const { projectRoot, appConfig } = wco;
   let exclude = [ '**/*.spec.ts' ];
@@ -24,18 +60,13 @@ export const getNonAotConfig = function(wco: WebpackConfigOptions) {
       ]
     },
     plugins: [
-      new AotPlugin({
-        tsConfigPath: path.resolve(projectRoot, appConfig.root, appConfig.tsconfig),
-        mainPath: path.join(projectRoot, appConfig.root, appConfig.main),
-        exclude: exclude,
-        skipCodeGeneration: true
-      }),
+      _createAotPlugin(wco, { exclude, skipCodeGeneration: true }),
     ]
   };
 };
 
 export const getAotConfig = function(wco: WebpackConfigOptions) {
-  const { projectRoot, buildOptions, appConfig } = wco;
+  const { projectRoot, appConfig } = wco;
   let exclude = [ '**/*.spec.ts' ];
   if (appConfig.test) { exclude.push(path.join(projectRoot, appConfig.root, appConfig.test)); };
   return {
@@ -49,14 +80,7 @@ export const getAotConfig = function(wco: WebpackConfigOptions) {
       ]
     },
     plugins: [
-      new AotPlugin({
-        tsConfigPath: path.resolve(projectRoot, appConfig.root, appConfig.tsconfig),
-        mainPath: path.join(projectRoot, appConfig.root, appConfig.main),
-        i18nFile: buildOptions.i18nFile,
-        i18nFormat: buildOptions.i18nFormat,
-        locale: buildOptions.locale,
-        exclude: exclude
-      })
+      _createAotPlugin(wco, { exclude })
     ]
   };
 };
diff --git a/packages/@ngtools/webpack/src/plugin.ts b/packages/@ngtools/webpack/src/plugin.ts
index acf7e2b2f629..8387e4c9536f 100644
--- a/packages/@ngtools/webpack/src/plugin.ts
+++ b/packages/@ngtools/webpack/src/plugin.ts
@@ -24,6 +24,7 @@ export interface AotPluginOptions {
   mainPath?: string;
   typeChecking?: boolean;
   skipCodeGeneration?: boolean;
+  hostOverrideFileSystem?: { [path: string]: string };
   i18nFile?: string;
   i18nFormat?: string;
   locale?: string;
@@ -167,6 +168,14 @@ export class AotPlugin implements Tapable {
     }
 
     this._compilerHost = new WebpackCompilerHost(this._compilerOptions, this._basePath);
+
+    // Override some files in the FileSystem.
+    if (options.hasOwnProperty('hostOverrideFileSystem')) {
+      for (const filePath of Object.keys(options.hostOverrideFileSystem)) {
+        this._compilerHost.writeFile(filePath, options.hostOverrideFileSystem[filePath], false);
+      }
+    }
+
     this._program = ts.createProgram(
       this._rootFilePath, this._compilerOptions, this._compilerHost);