diff --git a/packages/metro/src/DeltaBundler/DeltaCalculator.js b/packages/metro/src/DeltaBundler/DeltaCalculator.js
index b1f18b2f..4e280fbf 100644
--- a/packages/metro/src/DeltaBundler/DeltaCalculator.js
+++ b/packages/metro/src/DeltaBundler/DeltaCalculator.js
@@ -42,6 +42,7 @@ export type Options = {
   +minify: boolean,
   +onProgress: ?(doneCont: number, totalCount: number) => mixed,
   +platform: ?string,
+  +type: 'module' | 'script',
 };
 
 /**
@@ -199,6 +200,17 @@ class DeltaCalculator extends EventEmitter {
       projectRoot,
     };
 
+    // When we're processing scripts, we don't need to calculate any
+    // inlineRequires information, since scripts by definition don't have
+    // requires().
+    if (this._options.type === 'script') {
+      // $FlowIssue #23854098 - Object.assign() loses the strictness of an object in flow
+      return {
+        ...transformOptionsForBlacklist,
+        inlineRequires: false,
+      };
+    }
+
     const {
       inlineRequires,
     } = await this._bundler.getTransformOptionsForEntryFiles(
@@ -211,14 +223,14 @@ class DeltaCalculator extends EventEmitter {
             entryPoints: [path],
           },
           this._dependencyGraph,
-          transformOptionsForBlacklist,
+          {...transformOptionsForBlacklist, type: this._options.type},
         );
 
         return Array.from(added.keys());
       },
     );
 
-    // $FlowFixMe flow does not recognize well Object.assign() return types.
+    // $FlowIssue #23854098 - Object.assign() loses the strictness of an object in flow
     return {
       ...transformOptionsForBlacklist,
       inlineRequires: inlineRequires || false,
@@ -267,7 +279,10 @@ class DeltaCalculator extends EventEmitter {
     modifiedFiles: Set<string>,
     deletedFiles: Set<string>,
   ): Promise<DeltaResult> {
-    const transformerOptions = await this.getTransformerOptions();
+    const transformerOptions = {
+      ...(await this.getTransformerOptions()),
+      type: this._options.type,
+    };
 
     if (!this._graph.dependencies.size) {
       const {added} = await initialTraverseDependencies(
diff --git a/packages/metro/src/DeltaBundler/DeltaTransformer.js b/packages/metro/src/DeltaBundler/DeltaTransformer.js
index 197a7bb1..cb27fbb2 100644
--- a/packages/metro/src/DeltaBundler/DeltaTransformer.js
+++ b/packages/metro/src/DeltaBundler/DeltaTransformer.js
@@ -126,6 +126,7 @@ class DeltaTransformer extends EventEmitter {
     const deltaCalculator = new DeltaCalculator(bundler, dependencyGraph, {
       ...bundleOptions,
       entryPoints: [bundleOptions.entryFile],
+      type: 'module',
     });
 
     return new DeltaTransformer(
diff --git a/packages/metro/src/DeltaBundler/traverseDependencies.js b/packages/metro/src/DeltaBundler/traverseDependencies.js
index 08e50093..cb3ecc0b 100644
--- a/packages/metro/src/DeltaBundler/traverseDependencies.js
+++ b/packages/metro/src/DeltaBundler/traverseDependencies.js
@@ -52,6 +52,11 @@ type Delta = {
   deleted: Set<string>,
 };
 
+export type TransformOptions = {|
+  ...JSTransformerOptions,
+  type: 'module' | 'script',
+|};
+
 /**
  * Dependency Traversal logic for the Delta Bundler. This method calculates
  * the modules that should be included in the bundle by traversing the
@@ -69,7 +74,7 @@ type Delta = {
 async function traverseDependencies(
   paths: $ReadOnlyArray<string>,
   dependencyGraph: DependencyGraph,
-  transformOptions: JSTransformerOptions,
+  transformOptions: TransformOptions,
   graph: Graph,
   onProgress?: (numProcessed: number, total: number) => mixed = () => {},
 ): Promise<Result> {
@@ -136,11 +141,17 @@ async function traverseDependencies(
 async function initialTraverseDependencies(
   graph: Graph,
   dependencyGraph: DependencyGraph,
-  transformOptions: JSTransformerOptions,
+  transformOptions: TransformOptions,
   onProgress?: (numProcessed: number, total: number) => mixed = () => {},
 ): Promise<Result> {
   graph.entryPoints.forEach(entryPoint =>
-    createEdge(dependencyGraph.getModuleForPath(entryPoint), graph),
+    createEdge(
+      dependencyGraph.getModuleForPath(
+        entryPoint,
+        transformOptions.type === 'script',
+      ),
+      graph,
+    ),
   );
 
   await traverseDependencies(
@@ -162,7 +173,7 @@ async function initialTraverseDependencies(
 async function traverseDependenciesForSingleFile(
   edge: DependencyEdge,
   dependencyGraph: DependencyGraph,
-  transformOptions: JSTransformerOptions,
+  transformOptions: TransformOptions,
   graph: Graph,
   delta: Delta,
   onProgress?: (numProcessed: number, total: number) => mixed = () => {},
@@ -194,7 +205,7 @@ async function traverseDependenciesForSingleFile(
 async function processEdge(
   edge: DependencyEdge,
   dependencyGraph: DependencyGraph,
-  transformOptions: JSTransformerOptions,
+  transformOptions: TransformOptions,
   graph: Graph,
   delta: Delta,
   onDependencyAdd: () => mixed,
@@ -202,11 +213,12 @@ async function processEdge(
 ): Promise<void> {
   const previousDependencies = edge.dependencies;
 
-  const result = await dependencyGraph
-    .getModuleForPath(edge.path)
-    .read(
-      removeInlineRequiresBlacklistFromOptions(edge.path, transformOptions),
-    );
+  const {type, ...workerTransformOptions} = transformOptions;
+
+  const module = dependencyGraph.getModuleForPath(edge.path, type === 'script');
+  const result = await module.read(
+    removeInlineRequiresBlacklistFromOptions(edge.path, workerTransformOptions),
+  );
 
   // Get the absolute path of all sub-dependencies (some of them could have been
   // moved but maintain the same relative path).
@@ -262,7 +274,7 @@ async function addDependency(
   parentEdge: DependencyEdge,
   path: string,
   dependencyGraph: DependencyGraph,
-  transformOptions: JSTransformerOptions,
+  transformOptions: TransformOptions,
   graph: Graph,
   delta: Delta,
   onDependencyAdd: () => mixed,
@@ -277,7 +289,10 @@ async function addDependency(
     return;
   }
 
-  const edge = createEdge(dependencyGraph.getModuleForPath(path), graph);
+  const edge = createEdge(
+    dependencyGraph.getModuleForPath(path, transformOptions.type === 'script'),
+    graph,
+  );
 
   edge.inverseDependencies.add(parentEdge.path);
   delta.added.set(edge.path, edge);
@@ -365,11 +380,14 @@ function destroyEdge(edge: DependencyEdge, graph: Graph) {
 
 function resolveDependencies(
   parentPath,
-  dependencies: Array<string>,
+  dependencies: $ReadOnlyArray<string>,
   dependencyGraph: DependencyGraph,
-  transformOptions: JSTransformerOptions,
+  transformOptions: TransformOptions,
 ): Map<string, string> {
-  const parentModule = dependencyGraph.getModuleForPath(parentPath);
+  const parentModule = dependencyGraph.getModuleForPath(
+    parentPath,
+    transformOptions.type === 'string',
+  );
 
   return new Map(
     dependencies.map(relativePath => [
diff --git a/packages/metro/src/Server/__tests__/Server-test.js b/packages/metro/src/Server/__tests__/Server-test.js
index 0d677a85..d0f4cd30 100644
--- a/packages/metro/src/Server/__tests__/Server-test.js
+++ b/packages/metro/src/Server/__tests__/Server-test.js
@@ -466,6 +466,7 @@ describe('processRequest', () => {
             minify: false,
             onProgress: null,
             platform: undefined,
+            type: 'module',
           }),
         );
     });
diff --git a/packages/metro/src/Server/index.js b/packages/metro/src/Server/index.js
index 821e34ba..64b24138 100644
--- a/packages/metro/src/Server/index.js
+++ b/packages/metro/src/Server/index.js
@@ -245,7 +245,7 @@ class Server {
       this._opts.projectRoots,
     );
 
-    let graph = await this._deltaBundler.buildGraph({
+    const crawlingOptions = {
       assetPlugins: options.assetPlugins,
       customTransformOptions: options.customTransformOptions,
       dev: options.dev,
@@ -254,11 +254,14 @@ class Server {
       minify: options.minify,
       onProgress: options.onProgress,
       platform: options.platform,
-    });
+      type: 'module',
+    };
+
+    let graph = await this._deltaBundler.buildGraph(crawlingOptions);
     let prependScripts = await getPrependedScripts(
       this._opts,
-      options,
-      this._bundler,
+      crawlingOptions,
+      this._deltaBundler,
     );
 
     if (options.minify) {
@@ -973,6 +976,7 @@ class Server {
     runBeforeMainModule: [],
     runModule: true,
     sourceMapUrl: null,
+    type: 'script',
     unbundle: false,
   };
 }
diff --git a/packages/metro/src/__fixtures__/getTransformOptions.js b/packages/metro/src/__fixtures__/getTransformOptions.js
index 61ea5eec..dcb6a6db 100644
--- a/packages/metro/src/__fixtures__/getTransformOptions.js
+++ b/packages/metro/src/__fixtures__/getTransformOptions.js
@@ -43,6 +43,7 @@ async function getTransformOptions(): Promise<JSTransformerOptions> {
     hot: true,
     minify: false,
     platform: 'ios',
+    type: 'module',
   };
 
   const deltaCalculator = new DeltaCalculator(
diff --git a/packages/metro/src/lib/getPrependedScripts.js b/packages/metro/src/lib/getPrependedScripts.js
index 36085197..224471d6 100644
--- a/packages/metro/src/lib/getPrependedScripts.js
+++ b/packages/metro/src/lib/getPrependedScripts.js
@@ -13,27 +13,27 @@
 const defaults = require('../defaults');
 const getPreludeCode = require('./getPreludeCode');
 
-import type Bundler from '../Bundler';
 import type {DependencyEdge} from '../DeltaBundler/traverseDependencies';
-import type Module from '../node-haste/Module';
+import type DeltaBundler from '../DeltaBundler';
+import type {CustomTransformOptions} from '../JSTransformer/worker';
 
 type Options = {
-  enableBabelRCLookup: boolean,
   getPolyfills: ({platform: ?string}) => $ReadOnlyArray<string>,
   polyfillModuleNames: Array<string>,
-  projectRoots: $ReadOnlyArray<string>,
 };
 
 type BundleOptions = {
+  customTransformOptions: CustomTransformOptions,
   +dev: boolean,
   +hot: boolean,
+  +minify: boolean,
   +platform: ?string,
 };
 
 async function getPrependedScripts(
   options: Options,
   bundleOptions: BundleOptions,
-  bundler: Bundler,
+  deltaBundler: DeltaBundler,
 ): Promise<Array<DependencyEdge>> {
   // Get all the polyfills from the relevant option params (the
   // `getPolyfills()` method and the `polyfillModuleNames` variable).
@@ -43,32 +43,22 @@ async function getPrependedScripts(
     })
     .concat(options.polyfillModuleNames);
 
-  const dependencyGraph = await bundler.getDependencyGraph();
-
-  // Build the module system dependencies (scripts that need to
-  // be included at the very beginning of the bundle) + any polifyll.
-  const modules = [defaults.moduleSystem]
-    .concat(polyfillModuleNames)
-    .map(polyfillModuleName =>
-      dependencyGraph.createPolyfill({
-        file: polyfillModuleName,
-      }),
-    );
-
-  const transformOptions = {
+  const graph = await deltaBundler.buildGraph({
+    assetPlugins: [],
+    customTransformOptions: bundleOptions.customTransformOptions,
     dev: bundleOptions.dev,
-    enableBabelRCLookup: options.enableBabelRCLookup,
+    entryPoints: [defaults.moduleSystem, ...polyfillModuleNames],
     hot: bundleOptions.hot,
-    projectRoot: options.projectRoots[0],
-  };
+    minify: bundleOptions.minify,
+    onProgress: null,
+    platform: bundleOptions.platform,
+    type: 'script',
+  });
 
-  const out = await Promise.all(
-    modules.map(module => _createEdgeFromScript(module, transformOptions)),
-  );
-
-  out.unshift(_getPrelude({dev: bundleOptions.dev}));
-
-  return out;
+  return [
+    _getPrelude({dev: bundleOptions.dev}),
+    ...graph.dependencies.values(),
+  ];
 }
 
 function _getPrelude({dev}: {dev: boolean}): DependencyEdge {
@@ -88,38 +78,4 @@ function _getPrelude({dev}: {dev: boolean}): DependencyEdge {
   };
 }
 
-async function _createEdgeFromScript(
-  module: Module,
-  options: {
-    dev: boolean,
-    enableBabelRCLookup: boolean,
-    hot: boolean,
-    projectRoot: string,
-  },
-): Promise<DependencyEdge> {
-  const result = await module.read({
-    assetDataPlugins: [],
-    customTransformOptions: {},
-    dev: options.dev,
-    enableBabelRCLookup: options.enableBabelRCLookup,
-    hot: options.hot,
-    inlineRequires: false,
-    minify: false,
-    platform: undefined,
-    projectRoot: options.projectRoot,
-  });
-
-  return {
-    dependencies: new Map(),
-    inverseDependencies: new Set(),
-    path: module.path,
-    output: {
-      code: result.code,
-      map: result.map,
-      source: result.source,
-      type: 'script',
-    },
-  };
-}
-
 module.exports = getPrependedScripts;
diff --git a/packages/metro/src/node-haste/DependencyGraph.js b/packages/metro/src/node-haste/DependencyGraph.js
index aa940ffb..c5c669e9 100644
--- a/packages/metro/src/node-haste/DependencyGraph.js
+++ b/packages/metro/src/node-haste/DependencyGraph.js
@@ -238,7 +238,11 @@ class DependencyGraph extends EventEmitter {
     this._haste.end();
   }
 
-  getModuleForPath(entryFile: string) {
+  getModuleForPath(entryFile: string, isPolyfill: boolean): Module {
+    if (isPolyfill) {
+      return this._moduleCache.getPolyfillModule(entryFile);
+    }
+
     if (this._helpers.isAssetFile(entryFile)) {
       return this._moduleCache.getAssetModule(entryFile);
     }
diff --git a/packages/metro/src/node-haste/ModuleCache.js b/packages/metro/src/node-haste/ModuleCache.js
index a3f07eb6..d3b4b30b 100644
--- a/packages/metro/src/node-haste/ModuleCache.js
+++ b/packages/metro/src/node-haste/ModuleCache.js
@@ -87,7 +87,7 @@ class ModuleCache {
     this._roots = roots;
   }
 
-  getModule(filePath: string): Module {
+  getModule(filePath: string) {
     if (!this._moduleCache[filePath]) {
       this._moduleCache[filePath] = new Module({
         depGraphHelpers: this._depGraphHelpers,
@@ -129,6 +129,14 @@ class ModuleCache {
     return this._moduleCache[filePath];
   }
 
+  getPolyfillModule(filePath: string) {
+    if (!this._moduleCache[filePath]) {
+      this._moduleCache[filePath] = this.createPolyfill({file: filePath});
+    }
+
+    return this._moduleCache[filePath];
+  }
+
   getPackage(filePath: string): Package {
     if (!this._packageCache[filePath]) {
       this._packageCache[filePath] = new Package({
diff --git a/packages/metro/src/transformer.js b/packages/metro/src/transformer.js
index c4c2c99a..b148fbda 100644
--- a/packages/metro/src/transformer.js
+++ b/packages/metro/src/transformer.js
@@ -119,14 +119,6 @@ type Params = {
 };
 
 function transform({filename, options, src, plugins}: Params) {
-  options = options || {
-    assetDataPlugins: [],
-    platform: '',
-    projectRoot: '',
-    inlineRequires: false,
-    minify: false,
-  };
-
   const OLD_BABEL_ENV = process.env.BABEL_ENV;
   process.env.BABEL_ENV = options.dev ? 'development' : 'production';