diff --git a/packages/metro/src/Bundler.js b/packages/metro/src/Bundler.js
index de6707fa..e38c81b7 100644
--- a/packages/metro/src/Bundler.js
+++ b/packages/metro/src/Bundler.js
@@ -17,13 +17,18 @@ const assert = require('assert');
 const defaults = require('./defaults');
 const fs = require('fs');
 const getTransformCacheKeyFn = require('./lib/getTransformCacheKeyFn');
+const toLocalPath = require('./node-haste/lib/toLocalPath');
 
 const {Cache, stableHash} = require('metro-cache');
 
-import type {TransformedCode, WorkerOptions} from './JSTransformer/worker';
+import type {TransformResult} from './DeltaBundler/traverseDependencies';
+import type {
+  JsOutput,
+  WorkerOptions,
+  TransformedCode,
+} from './JSTransformer/worker';
 import type {DynamicRequiresBehavior} from './ModuleGraph/worker/collectDependencies';
 import type {Reporter} from './lib/reporting';
-import type Module from './node-haste/Module';
 import type {BabelSourceMap} from '@babel/core';
 import type {CacheStore} from 'metro-cache';
 import type {CustomResolver} from 'metro-resolver';
@@ -147,7 +152,7 @@ class Bundler {
       reporter: opts.reporter,
       resolveRequest: opts.resolveRequest,
       sourceExts: opts.sourceExts,
-      transformCode: this._cachedTransformCode.bind(this),
+      transformCode: this.transformFile.bind(this),
       watch: opts.watch,
     });
 
@@ -215,10 +220,10 @@ class Bundler {
     return this._depGraphPromise;
   }
 
-  async _cachedTransformCode(
-    module: Module,
+  async transformFile(
+    filePath: string,
     transformCodeOptions: WorkerOptions,
-  ): Promise<TransformedCode> {
+  ): Promise<TransformResult<JsOutput>> {
     const cache = this._cache;
 
     const {
@@ -243,12 +248,14 @@ class Bundler {
       }
     }
 
+    const localPath = toLocalPath(this._projectRoots, filePath);
+
     const partialKey = stableHash([
       // This is the hash related to the global Bundler config.
       this._baseHash,
 
       // Path.
-      module.localPath,
+      localPath,
 
       // We cannot include "transformCodeOptions" because of "projectRoot".
       assetDataPlugins,
@@ -262,7 +269,7 @@ class Bundler {
       platform,
     ]);
 
-    const sha1 = (await this.getDependencyGraph()).getSha1(module.path);
+    const sha1 = (await this.getDependencyGraph()).getSha1(filePath);
     let fullKey = Buffer.concat([partialKey, Buffer.from(sha1, 'hex')]);
     const result = await cache.get(fullKey);
 
@@ -271,8 +278,8 @@ class Bundler {
     const data = result
       ? {result, sha1}
       : await this._transformer.transform(
-          module.path,
-          module.localPath,
+          filePath,
+          localPath,
           transformCodeOptions,
           this._opts.assetExts,
           this._opts.assetRegistryPath,
@@ -288,7 +295,12 @@ class Bundler {
 
     cache.set(fullKey, data.result);
 
-    return data.result;
+    return {
+      ...data.result,
+      getSource() {
+        return fs.readFileSync(filePath, 'utf8');
+      },
+    };
   }
 }
 
diff --git a/packages/metro/src/Bundler/__tests__/Bundler-test.js b/packages/metro/src/Bundler/__tests__/Bundler-test.js
index 567c9349..e377735b 100644
--- a/packages/metro/src/Bundler/__tests__/Bundler-test.js
+++ b/packages/metro/src/Bundler/__tests__/Bundler-test.js
@@ -127,7 +127,7 @@ describe('Bundler', function() {
       result: {},
     });
 
-    await bundlerInstance._cachedTransformCode(module, {});
+    await bundlerInstance.transformFile(module.path, {});
 
     // We got the SHA-1 of the file from the dependency graph.
     expect(depGraph.getSha1).toBeCalledWith('/root/foo.js');
diff --git a/packages/metro/src/DeltaBundler/traverseDependencies.js b/packages/metro/src/DeltaBundler/traverseDependencies.js
index 8a5069f5..c2fa4f36 100644
--- a/packages/metro/src/DeltaBundler/traverseDependencies.js
+++ b/packages/metro/src/DeltaBundler/traverseDependencies.js
@@ -44,11 +44,13 @@ type Delta<T> = {
   deleted: Set<string>,
 };
 
-export type TransformFn<T> = string => Promise<{|
+export type TransformResult<T> = {|
   dependencies: $ReadOnlyArray<TransformResultDependency>,
   output: $ReadOnlyArray<T>,
   +getSource: () => string,
-|}>;
+|};
+
+export type TransformFn<T> = string => Promise<TransformResult<T>>;
 
 export type Options<T> = {|
   resolve: (from: string, to: string) => string,
diff --git a/packages/metro/src/lib/transformHelpers.js b/packages/metro/src/lib/transformHelpers.js
index 75d58b29..8d3510ac 100644
--- a/packages/metro/src/lib/transformHelpers.js
+++ b/packages/metro/src/lib/transformHelpers.js
@@ -89,7 +89,6 @@ async function getTransformFn(
   deltaBundler: DeltaBundler<JsOutput>,
   options: BuildGraphOptions,
 ): Promise<TransformFn<JsOutput>> {
-  const dependencyGraph = await bundler.getDependencyGraph();
   const {inlineRequires, ...transformerOptions} = await calcTransformerOptions(
     entryFiles,
     bundler,
@@ -98,25 +97,13 @@ async function getTransformFn(
   );
 
   return async (path: string) => {
-    const module = dependencyGraph.getModuleForPath(
-      path,
-      options.type === 'script',
-    );
-    const result = await module.read({
+    return await bundler.transformFile(path, {
       ...transformerOptions,
       inlineRequires: removeInlineRequiresBlacklistFromOptions(
         path,
         inlineRequires,
       ),
     });
-
-    return {
-      getSource() {
-        return result.source;
-      },
-      output: result.output,
-      dependencies: result.dependencies,
-    };
   };
 }
 
diff --git a/packages/metro/src/node-haste/Module.js b/packages/metro/src/node-haste/Module.js
index 307748ad..857fec7c 100644
--- a/packages/metro/src/node-haste/Module.js
+++ b/packages/metro/src/node-haste/Module.js
@@ -22,10 +22,7 @@ type ReadResult = {
   +source: string,
 };
 
-export type TransformCode = (
-  module: Module,
-  transformOptions: WorkerOptions,
-) => Promise<TransformedCode>;
+export type TransformCode = Function;
 
 export type ConstructorArgs = {
   file: string,