diff --git a/packages/metro/src/Bundler.js b/packages/metro/src/Bundler.js
index 0b9691fe..0e0b3fda 100644
--- a/packages/metro/src/Bundler.js
+++ b/packages/metro/src/Bundler.js
@@ -291,12 +291,6 @@ class Bundler {
       }
     }
 
-    if (!cache && code == null) {
-      throw new Error(
-        'When not using experimental caches, code should always be provided',
-      );
-    }
-
     // Second, if there was no result, compute it ourselves.
     if (!data) {
       data = await this._transformer.transform(
diff --git a/packages/metro/src/DeltaBundler/__tests__/__snapshots__/traverseDependencies-integration-test.js.snap b/packages/metro/src/DeltaBundler/__tests__/__snapshots__/traverseDependencies-integration-test.js.snap
index 3269d478..c4473ec8 100644
--- a/packages/metro/src/DeltaBundler/__tests__/__snapshots__/traverseDependencies-integration-test.js.snap
+++ b/packages/metro/src/DeltaBundler/__tests__/__snapshots__/traverseDependencies-integration-test.js.snap
@@ -7,7 +7,7 @@ Array [
       "a",
       "b",
     ],
-    "id": "index",
+    "id": "index.js",
     "isAsset": false,
     "isPolyfill": false,
     "path": "/root/index.js",
@@ -15,7 +15,7 @@ Array [
   },
   Object {
     "dependencies": Array [],
-    "id": "a",
+    "id": "a.js",
     "isAsset": false,
     "isPolyfill": false,
     "path": "/root/a.js",
@@ -23,7 +23,7 @@ Array [
   },
   Object {
     "dependencies": Array [],
-    "id": "b",
+    "id": "b.js",
     "isAsset": false,
     "isPolyfill": false,
     "path": "/root/b.js",
diff --git a/packages/metro/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js b/packages/metro/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js
index 61c0ff62..dc7eeb36 100644
--- a/packages/metro/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js
+++ b/packages/metro/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js
@@ -133,11 +133,15 @@ describe('traverseDependencies', function() {
       transformCache: require('TransformCaching').mocked(),
       transformCode: (module, sourceCode, transformOptions) => {
         return new Promise(resolve => {
+          // require call must stay inline, so the latest defined mock is used!
+          const code = require('fs').readFileSync(module.path, 'utf8');
           const deps = {dependencies: []};
+
           if (!module.path.endsWith('.json')) {
-            deps.dependencies = extractDependencies(sourceCode);
+            deps.dependencies = extractDependencies(code);
           }
-          resolve({...deps, code: sourceCode});
+
+          resolve({...deps, code});
         });
       },
       getTransformCacheKey: () => 'abcdef',
@@ -191,7 +195,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['a'],
             isAsset: false,
@@ -200,7 +204,7 @@ describe('traverseDependencies', function() {
             resolveDependency: undefined,
           },
           {
-            id: 'a',
+            id: 'a.js',
             path: '/root/a.js',
             dependencies: ['b'],
             isAsset: false,
@@ -209,7 +213,7 @@ describe('traverseDependencies', function() {
             resolveDependency: undefined,
           },
           {
-            id: 'b',
+            id: 'b.js',
             path: '/root/b.js',
             dependencies: [],
             isAsset: false,
@@ -248,7 +252,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'a',
+            id: 'a.js',
             path: '/root/a.js',
             dependencies: ['b'],
             isAsset: false,
@@ -281,14 +285,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['a'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'a',
+            id: 'a.js',
             path: '/root/a.js',
             dependencies: [],
             isAsset: false,
@@ -325,21 +329,21 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['./a.json', './b'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'package/a.json',
+            id: 'a.json',
             path: '/root/a.json',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'package/b.json',
+            id: 'b.json',
             path: '/root/b.json',
             dependencies: [],
             isAsset: false,
@@ -373,14 +377,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['./package.json'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'package/package.json',
+            id: 'package.json',
             path: '/root/package.json',
             dependencies: [],
             isAsset: false,
@@ -417,7 +421,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['./imgs/a.png'],
             isAsset: false,
@@ -466,7 +470,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['./imgs/a.png', './imgs/b.png', './imgs/c.png'],
             isAsset: false,
@@ -530,7 +534,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['./imgs/a.png', './imgs/b.png', './imgs/c.png'],
             isAsset: false,
@@ -588,14 +592,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['a'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'a',
+            id: 'a.js',
             path: '/root/a.js',
             dependencies: ['index'],
             isAsset: false,
@@ -633,7 +637,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['aPackage'],
             isAsset: false,
@@ -678,7 +682,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['aPackage/'],
             isAsset: false,
@@ -731,7 +735,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['sha.js', 'x.y.z'],
             isAsset: false,
@@ -825,7 +829,7 @@ describe('traverseDependencies', function() {
             isPolyfill: false,
           },
           {
-            id: 'EpicModule',
+            id: 'aPackage/index.js',
             path: '/root/aPackage/index.js',
             dependencies: [],
             isAsset: false,
@@ -899,14 +903,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'test/index.js',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['./lib/'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'test/lib/index.js',
+            id: 'lib/index.js',
             path: '/root/lib/index.js',
             dependencies: [],
             isAsset: false,
@@ -942,14 +946,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'test/index.js',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['./lib/'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: '/root/lib/main.js',
+            id: 'lib/main.js',
             path: '/root/lib/main.js',
             dependencies: [],
             isAsset: false,
@@ -979,7 +983,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: [],
             isAsset: false,
@@ -1074,7 +1078,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['aPackage/subdir/lolynot'],
             isAsset: false,
@@ -1127,7 +1131,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['aPackage'],
             isAsset: false,
@@ -1216,7 +1220,7 @@ describe('traverseDependencies', function() {
             );
             expect(deps).toEqual([
               {
-                id: 'index',
+                id: 'index.js',
                 path: '/root/index.js',
                 dependencies: ['aPackage'],
                 isAsset: false,
@@ -1277,7 +1281,7 @@ describe('traverseDependencies', function() {
             );
             expect(deps).toEqual([
               {
-                id: 'index',
+                id: 'index.js',
                 path: '/root/index.js',
                 dependencies: ['aPackage'],
                 isAsset: false,
@@ -1340,7 +1344,7 @@ describe('traverseDependencies', function() {
             );
             expect(deps).toEqual([
               {
-                id: 'index',
+                id: 'index.js',
                 path: '/root/index.js',
                 dependencies: ['aPackage'],
                 isAsset: false,
@@ -1401,7 +1405,7 @@ describe('traverseDependencies', function() {
           );
           expect(deps).toEqual([
             {
-              id: 'index',
+              id: 'index.js',
               path: '/root/index.js',
               dependencies: ['aPackage'],
               isAsset: false,
@@ -1465,7 +1469,7 @@ describe('traverseDependencies', function() {
             );
             expect(deps).toEqual([
               {
-                id: 'index',
+                id: 'index.js',
                 path: '/root/index.js',
                 dependencies: ['aPackage'],
                 isAsset: false,
@@ -1539,7 +1543,7 @@ describe('traverseDependencies', function() {
             );
             expect(deps).toEqual([
               {
-                id: 'index',
+                id: 'index.js',
                 path: '/root/index.js',
                 dependencies: ['aPackage'],
                 isAsset: false,
@@ -1634,7 +1638,7 @@ describe('traverseDependencies', function() {
             );
             expect(deps).toEqual([
               {
-                id: 'index',
+                id: 'index.js',
                 path: '/root/index.js',
                 dependencies: ['aPackage'],
                 isAsset: false,
@@ -1648,7 +1652,7 @@ describe('traverseDependencies', function() {
                 isPolyfill: false,
               },
               {
-                id: 'browser-package/index.js',
+                id: 'aPackage/browser-package/index.js',
                 path: '/root/aPackage/browser-package/index.js',
                 dependencies: [],
                 isAsset: false,
@@ -1708,7 +1712,7 @@ describe('traverseDependencies', function() {
             );
             expect(deps).toEqual([
               {
-                id: 'index',
+                id: 'index.js',
                 path: '/root/index.js',
                 dependencies: ['aPackage'],
                 isAsset: false,
@@ -1789,7 +1793,7 @@ describe('traverseDependencies', function() {
             );
             expect(deps).toEqual([
               {
-                id: 'index',
+                id: 'index.js',
                 path: '/root/index.js',
                 dependencies: ['aPackage'],
                 isAsset: false,
@@ -1803,7 +1807,7 @@ describe('traverseDependencies', function() {
                 isPolyfill: false,
               },
               {
-                id: 'browser-package/index.js',
+                id: 'aPackage/browser-package/index.js',
                 path: '/root/aPackage/browser-package/index.js',
                 dependencies: [],
                 isAsset: false,
@@ -1860,7 +1864,7 @@ describe('traverseDependencies', function() {
             );
             expect(deps).toEqual([
               {
-                id: 'index',
+                id: 'index.js',
                 path: '/root/index.js',
                 dependencies: ['aPackage'],
                 isAsset: false,
@@ -1927,7 +1931,7 @@ describe('traverseDependencies', function() {
             );
             expect(deps).toEqual([
               {
-                id: 'index',
+                id: 'index.js',
                 path: '/root/index.js',
                 dependencies: ['aPackage'],
                 isAsset: false,
@@ -2006,7 +2010,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['aPackage'],
             isAsset: false,
@@ -2020,14 +2024,14 @@ describe('traverseDependencies', function() {
             isPolyfill: false,
           },
           {
-            id: 'rn-package/index.js',
+            id: 'aPackage/node_modules/rn-package/index.js',
             path: '/root/aPackage/node_modules/rn-package/index.js',
             dependencies: ['nested-package'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'nested-browser-package/index.js',
+            id: 'aPackage/node_modules/nested-browser-package/index.js',
             path: '/root/aPackage/node_modules/nested-browser-package/index.js',
             dependencies: [],
             isAsset: false,
@@ -2161,7 +2165,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['aPackage'],
             isAsset: false,
@@ -2179,21 +2183,21 @@ describe('traverseDependencies', function() {
             isPolyfill: false,
           },
           {
-            id: 'rn-package-a/index.js',
+            id: 'aPackage/node_modules/rn-package-a/index.js',
             path: '/root/aPackage/node_modules/rn-package-a/index.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'rn-package-b/index.js',
+            id: 'aPackage/node_modules/rn-package-b/index.js',
             path: '/root/aPackage/node_modules/rn-package-b/index.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'rn-package-d/index.js',
+            id: 'aPackage/node_modules/rn-package-d/index.js',
             path: '/root/aPackage/node_modules/rn-package-d/index.js',
             dependencies: [],
             isAsset: false,
@@ -2248,7 +2252,7 @@ describe('traverseDependencies', function() {
             isPolyfill: false,
           },
           {
-            id: '/root/provides-bar/lib/bar.js',
+            id: 'provides-bar/lib/bar.js',
             path: '/root/provides-bar/lib/bar.js',
             dependencies: [],
             isAsset: false,
@@ -2332,7 +2336,7 @@ describe('traverseDependencies', function() {
             isPolyfill: false,
           },
           {
-            id: '/root/provides-bar/lib/foo.js',
+            id: 'provides-bar/lib/foo.js',
             path: '/root/provides-bar/lib/foo.js',
             dependencies: [],
             isAsset: false,
@@ -2390,7 +2394,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: 'C:\\root\\index.js',
             dependencies: ['a'],
             isAsset: false,
@@ -2399,7 +2403,7 @@ describe('traverseDependencies', function() {
             resolveDependency: undefined,
           },
           {
-            id: 'a',
+            id: 'a.js',
             path: 'C:\\root\\a.js',
             dependencies: ['b'],
             isAsset: false,
@@ -2408,7 +2412,7 @@ describe('traverseDependencies', function() {
             resolveDependency: undefined,
           },
           {
-            id: 'b',
+            id: 'b.js',
             path: 'C:\\root\\b.js',
             dependencies: [],
             isAsset: false,
@@ -2486,7 +2490,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: 'C:\\root\\index.js',
             dependencies: ['./imgs/a.png', './imgs/b.png', './imgs/c.png'],
             isAsset: false,
@@ -2580,28 +2584,28 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['foo', 'bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/main.js',
+            id: 'node_modules/foo/main.js',
             path: '/root/node_modules/foo/main.js',
             dependencies: ['bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main.js',
+            id: 'node_modules/foo/node_modules/bar/main.js',
             path: '/root/node_modules/foo/node_modules/bar/main.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main.js',
+            id: 'node_modules/bar/main.js',
             path: '/root/node_modules/bar/main.js',
             dependencies: [],
             isAsset: false,
@@ -2649,21 +2653,21 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.ios.js',
             path: '/root/index.ios.js',
             dependencies: ['foo', 'bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/index.ios.js',
+            id: 'node_modules/foo/index.ios.js',
             path: '/root/node_modules/foo/index.ios.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main.ios.js',
+            id: 'node_modules/bar/main.ios.js',
             path: '/root/node_modules/bar/main.ios.js',
             dependencies: [],
             isAsset: false,
@@ -2721,28 +2725,28 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['foo', 'bar/'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/main.js',
+            id: 'node_modules/foo/main.js',
             path: '/root/node_modules/foo/main.js',
             dependencies: ['bar/lol'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/lol.js',
+            id: 'node_modules/foo/node_modules/bar/lol.js',
             path: '/root/node_modules/foo/node_modules/bar/lol.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main.js',
+            id: 'node_modules/bar/main.js',
             path: '/root/node_modules/bar/main.js',
             dependencies: [],
             isAsset: false,
@@ -2804,28 +2808,28 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['foo', 'bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/main.js',
+            id: 'node_modules/foo/main.js',
             path: '/root/node_modules/foo/main.js',
             dependencies: ['bar/lol'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/lol.js',
+            id: 'node_modules/foo/node_modules/bar/lol.js',
             path: '/root/node_modules/foo/node_modules/bar/lol.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main2.js',
+            id: 'node_modules/bar/main2.js',
             path: '/root/node_modules/bar/main2.js',
             dependencies: [],
             isAsset: false,
@@ -2876,21 +2880,21 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar',
+            id: 'path/to/bar.js',
             path: '/root/path/to/bar.js',
             dependencies: ['foo'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/main.js',
+            id: 'node_modules/foo/main.js',
             path: '/root/node_modules/foo/main.js',
             dependencies: [],
             isAsset: false,
@@ -3023,7 +3027,7 @@ describe('traverseDependencies', function() {
           .then(deps => {
             expect(deps).toEqual([
               {
-                id: 'index',
+                id: 'index.js',
                 path: '/root/index.js',
                 dependencies: [
                   'shouldWork',
@@ -3035,14 +3039,14 @@ describe('traverseDependencies', function() {
                 isPolyfill: false,
               },
               {
-                id: 'shouldWork',
+                id: 'node_modules/react-haste/main.js',
                 path: '/root/node_modules/react-haste/main.js',
                 dependencies: ['submodule'],
                 isAsset: false,
                 isPolyfill: false,
               },
               {
-                id: 'submodule/main.js',
+                id: 'node_modules/react-haste/node_modules/submodule/main.js',
                 path:
                   '/root/node_modules/react-haste/node_modules/submodule/main.js',
                 dependencies: [],
@@ -3050,21 +3054,21 @@ describe('traverseDependencies', function() {
                 isPolyfill: false,
               },
               {
-                id: 'ember/main.js',
+                id: 'node_modules/ember/main.js',
                 path: '/root/node_modules/ember/main.js',
                 dependencies: [],
                 isAsset: false,
                 isPolyfill: false,
               },
               {
-                id: 'internalVendoredPackage',
+                id: 'vendored_modules/a-vendored-package/main.js',
                 path: '/root/vendored_modules/a-vendored-package/main.js',
                 dependencies: [],
                 isAsset: false,
                 isPolyfill: false,
               },
               {
-                id: 'anotherIndex',
+                id: 'index.js',
                 path: '/anotherRoot/index.js',
                 dependencies: [],
                 isAsset: false,
@@ -3107,14 +3111,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/react-haste/index.js',
             dependencies: ['shouldWork'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'shouldWork',
+            id: 'node_modules/react-haste/main.js',
             path: '/react-haste/node_modules/react-haste/main.js',
             dependencies: [],
             isAsset: false,
@@ -3154,14 +3158,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['sha.js'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'sha.js/main.js',
+            id: 'node_modules/sha.js/main.js',
             path: '/root/node_modules/sha.js/main.js',
             dependencies: [],
             isAsset: false,
@@ -3208,14 +3212,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.ios.js',
             path: '/root/index.ios.js',
             dependencies: ['a'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'a',
+            id: 'a.ios.js',
             path: '/root/a.ios.js',
             dependencies: [],
             isAsset: false,
@@ -3265,14 +3269,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.ios.js',
             path: '/root/index.ios.js',
             dependencies: ['a'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'a',
+            id: 'a.js',
             path: '/root/a.js',
             dependencies: [],
             isAsset: false,
@@ -3307,7 +3311,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.ios.js',
             path: '/root/index.ios.js',
             dependencies: ['./a'],
             isAsset: false,
@@ -3361,28 +3365,28 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['foo/package.json', 'bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/package.json',
+            id: 'node_modules/foo/package.json',
             path: '/root/node_modules/foo/package.json',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main.js',
+            id: 'node_modules/bar/main.js',
             path: '/root/node_modules/bar/main.js',
             dependencies: ['./package.json'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/package.json',
+            id: 'node_modules/bar/package.json',
             path: '/root/node_modules/bar/package.json',
             dependencies: [],
             isAsset: false,
@@ -3421,7 +3425,7 @@ describe('traverseDependencies', function() {
             isPolyfill: false,
           },
           {
-            id: 'a/index.js',
+            id: 'node_modules/a/index.js',
             path: '/root/node_modules/a/index.js',
             dependencies: [],
             isAsset: false,
@@ -3505,28 +3509,28 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: 'C:\\root\\index.js',
             dependencies: ['foo', 'bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/main.js',
+            id: 'node_modules\\foo\\main.js',
             path: 'C:\\root\\node_modules\\foo\\main.js',
             dependencies: ['bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main.js',
+            id: 'node_modules\\foo\\node_modules\\bar\\main.js',
             path: 'C:\\root\\node_modules\\foo\\node_modules\\bar\\main.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main.js',
+            id: 'node_modules\\bar\\main.js',
             path: 'C:\\root\\node_modules\\bar\\main.js',
             dependencies: [],
             isAsset: false,
@@ -3574,21 +3578,21 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.ios.js',
             path: 'C:\\root\\index.ios.js',
             dependencies: ['foo', 'bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/index.ios.js',
+            id: 'node_modules\\foo\\index.ios.js',
             path: 'C:\\root\\node_modules\\foo\\index.ios.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main.ios.js',
+            id: 'node_modules\\bar\\main.ios.js',
             path: 'C:\\root\\node_modules\\bar\\main.ios.js',
             dependencies: [],
             isAsset: false,
@@ -3646,28 +3650,28 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: 'C:\\root\\index.js',
             dependencies: ['foo', 'bar/'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/main.js',
+            id: 'node_modules\\foo\\main.js',
             path: 'C:\\root\\node_modules\\foo\\main.js',
             dependencies: ['bar/lol'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/lol.js',
+            id: 'node_modules\\foo\\node_modules\\bar\\lol.js',
             path: 'C:\\root\\node_modules\\foo\\node_modules\\bar\\lol.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main.js',
+            id: 'node_modules\\bar\\main.js',
             path: 'C:\\root\\node_modules\\bar\\main.js',
             dependencies: [],
             isAsset: false,
@@ -3729,28 +3733,28 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: 'C:\\root\\index.js',
             dependencies: ['foo', 'bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/main.js',
+            id: 'node_modules\\foo\\main.js',
             path: 'C:\\root\\node_modules\\foo\\main.js',
             dependencies: ['bar/lol'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/lol.js',
+            id: 'node_modules\\foo\\node_modules\\bar\\lol.js',
             path: 'C:\\root\\node_modules\\foo\\node_modules\\bar\\lol.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main2.js',
+            id: 'node_modules\\bar\\main2.js',
             path: 'C:\\root\\node_modules\\bar\\main2.js',
             dependencies: [],
             isAsset: false,
@@ -3801,21 +3805,21 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: 'C:\\root\\index.js',
             dependencies: ['bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar',
+            id: 'path\\to\\bar.js',
             path: 'C:\\root\\path\\to\\bar.js',
             dependencies: ['foo'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/main.js',
+            id: 'node_modules\\foo\\main.js',
             path: 'C:\\root\\node_modules\\foo\\main.js',
             dependencies: [],
             isAsset: false,
@@ -3948,7 +3952,7 @@ describe('traverseDependencies', function() {
         const deps = await getOrderedDependenciesAsJSON(dgraph, entryPath);
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: 'C:\\root\\index.js',
             dependencies: [
               'shouldWork',
@@ -3960,14 +3964,14 @@ describe('traverseDependencies', function() {
             isPolyfill: false,
           },
           {
-            id: 'shouldWork',
+            id: 'node_modules\\react-haste\\main.js',
             path: 'C:\\root\\node_modules\\react-haste\\main.js',
             dependencies: ['submodule'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'submodule/main.js',
+            id: 'node_modules\\react-haste\\node_modules\\submodule\\main.js',
             path:
               'C:\\root\\node_modules\\react-haste\\node_modules\\submodule\\main.js',
             dependencies: [],
@@ -3975,21 +3979,21 @@ describe('traverseDependencies', function() {
             isPolyfill: false,
           },
           {
-            id: 'ember/main.js',
+            id: 'node_modules\\ember\\main.js',
             path: 'C:\\root\\node_modules\\ember\\main.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'internalVendoredPackage',
+            id: 'vendored_modules\\a-vendored-package\\main.js',
             path: 'C:\\root\\vendored_modules\\a-vendored-package\\main.js',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'anotherIndex',
+            id: 'index.js',
             path: 'C:\\anotherRoot\\index.js',
             dependencies: [],
             isAsset: false,
@@ -4031,14 +4035,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: 'C:\\react-haste\\index.js',
             dependencies: ['shouldWork'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'shouldWork',
+            id: 'node_modules\\react-haste\\main.js',
             path: 'C:\\react-haste\\node_modules\\react-haste\\main.js',
             dependencies: [],
             isAsset: false,
@@ -4078,14 +4082,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: 'C:\\root\\index.js',
             dependencies: ['sha.js'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'sha.js/main.js',
+            id: 'node_modules\\sha.js\\main.js',
             path: 'C:\\root\\node_modules\\sha.js\\main.js',
             dependencies: [],
             isAsset: false,
@@ -4132,14 +4136,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.ios.js',
             path: 'C:\\root\\index.ios.js',
             dependencies: ['a'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'a',
+            id: 'a.ios.js',
             path: 'C:\\root\\a.ios.js',
             dependencies: [],
             isAsset: false,
@@ -4185,14 +4189,14 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.ios.js',
             path: 'C:\\root\\index.ios.js',
             dependencies: ['a'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'a',
+            id: 'a.js',
             path: 'C:\\root\\a.js',
             dependencies: [],
             isAsset: false,
@@ -4227,7 +4231,7 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.ios.js',
             path: 'C:\\root\\index.ios.js',
             dependencies: ['./a'],
             isAsset: false,
@@ -4281,28 +4285,28 @@ describe('traverseDependencies', function() {
         );
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: 'C:\\root\\index.js',
             dependencies: ['foo/package.json', 'bar'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'foo/package.json',
+            id: 'node_modules\\foo\\package.json',
             path: 'C:\\root\\node_modules\\foo\\package.json',
             dependencies: [],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/main.js',
+            id: 'node_modules\\bar\\main.js',
             path: 'C:\\root\\node_modules\\bar\\main.js',
             dependencies: ['./package.json'],
             isAsset: false,
             isPolyfill: false,
           },
           {
-            id: 'bar/package.json',
+            id: 'node_modules\\bar\\package.json',
             path: 'C:\\root\\node_modules\\bar\\package.json',
             dependencies: [],
             isAsset: false,
@@ -4370,7 +4374,7 @@ describe('traverseDependencies', function() {
         const deps = await getOrderedDependenciesAsJSON(dgraph, entryPath);
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['aPackage'],
             isAsset: false,
@@ -4427,7 +4431,7 @@ describe('traverseDependencies', function() {
         const deps = await getOrderedDependenciesAsJSON(dgraph, entryPath);
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['aPackage'],
             isAsset: false,
@@ -4535,7 +4539,7 @@ describe('traverseDependencies', function() {
         const deps = await getOrderedDependenciesAsJSON(dgraph, entryPath);
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['aPackage', 'foo'],
             isAsset: false,
@@ -4549,7 +4553,7 @@ describe('traverseDependencies', function() {
             isPolyfill: false,
           },
           {
-            id: 'bar',
+            id: 'bar.js',
             path: '/root/bar.js',
             dependencies: ['foo'],
             isAsset: false,
@@ -4557,7 +4561,7 @@ describe('traverseDependencies', function() {
             resolveDependency: undefined,
           },
           {
-            id: 'foo',
+            id: 'foo.js',
             path: '/root/foo.js',
             dependencies: ['aPackage'],
             isAsset: false,
@@ -4603,7 +4607,7 @@ describe('traverseDependencies', function() {
         const deps = await getOrderedDependenciesAsJSON(dgraph, entryPath);
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['./foo.png'],
             isAsset: false,
@@ -4661,7 +4665,7 @@ describe('traverseDependencies', function() {
         const deps = await getOrderedDependenciesAsJSON(dgraph, entryPath);
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['aPackage'],
             isAsset: false,
@@ -4727,7 +4731,7 @@ describe('traverseDependencies', function() {
         expect(deps).toEqual([
           {
             dependencies: ['bPackage'],
-            id: 'index',
+            id: 'index.js',
             isAsset: false,
             isPolyfill: false,
             path: '/root/index.js',
@@ -4735,7 +4739,7 @@ describe('traverseDependencies', function() {
           },
           {
             dependencies: [],
-            id: 'bPackage/main.js',
+            id: 'aPackage/main.js',
             isAsset: false,
             isPolyfill: false,
             path: '/root/aPackage/main.js',
@@ -4782,7 +4786,7 @@ describe('traverseDependencies', function() {
         const deps = await getOrderedDependenciesAsJSON(dgraph, entryPath);
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['foo'],
             isAsset: false,
@@ -4790,7 +4794,7 @@ describe('traverseDependencies', function() {
             resolveDependency: undefined,
           },
           {
-            id: 'foo/main.js',
+            id: 'node_modules/foo/main.js',
             path: '/root/node_modules/foo/main.js',
             dependencies: ['bar'],
             isAsset: false,
@@ -4798,7 +4802,7 @@ describe('traverseDependencies', function() {
             resolveDependency: undefined,
           },
           {
-            id: 'bar/main.js',
+            id: 'node_modules/foo/node_modules/bar/main.js',
             path: '/root/node_modules/foo/node_modules/bar/main.js',
             dependencies: [],
             isAsset: false,
@@ -4813,7 +4817,7 @@ describe('traverseDependencies', function() {
         const deps2 = await getOrderedDependenciesAsJSON(dgraph, entryPath);
         expect(deps2).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['foo'],
             isAsset: false,
@@ -4821,7 +4825,7 @@ describe('traverseDependencies', function() {
             resolveDependency: undefined,
           },
           {
-            id: 'foo/main.js',
+            id: 'node_modules/foo/main.js',
             path: '/root/node_modules/foo/main.js',
             dependencies: [],
             isAsset: false,
@@ -4874,7 +4878,7 @@ describe('traverseDependencies', function() {
         const deps = await getOrderedDependenciesAsJSON(dgraph, entryPath);
         expect(deps).toEqual([
           {
-            id: 'index',
+            id: 'index.js',
             path: '/root/index.js',
             dependencies: ['foo'],
             isAsset: false,
@@ -4882,7 +4886,7 @@ describe('traverseDependencies', function() {
             resolveDependency: undefined,
           },
           {
-            id: 'foo/browser.js',
+            id: 'node_modules/foo/browser.js',
             path: '/root/node_modules/foo/browser.js',
             dependencies: [],
             isAsset: false,
@@ -4984,14 +4988,14 @@ describe('traverseDependencies', function() {
         expect(deps).toEqual([
           {
             dependencies: ['a'],
-            id: 'index',
+            id: 'index.jsx',
             isAsset: false,
             isPolyfill: false,
             path: '/root/index.jsx',
           },
           {
             dependencies: [],
-            id: 'a',
+            id: 'a.coffee',
             isAsset: false,
             isPolyfill: false,
             path: '/root/a.coffee',
@@ -5288,7 +5292,7 @@ describe('traverseDependencies', function() {
 
   function setMockFileSystem(object) {
     const fs = require('fs');
-    const root = process.platform === 'win32' ? 'c:\\' : '/';
+    const root = process.platform === 'win32' ? 'C:\\' : '/';
     mockDir(fs, root, {...object, tmp: {}});
   }
 
diff --git a/packages/metro/src/node-haste/AssetModule.js b/packages/metro/src/node-haste/AssetModule.js
index 9d683877..48488064 100644
--- a/packages/metro/src/node-haste/AssetModule.js
+++ b/packages/metro/src/node-haste/AssetModule.js
@@ -12,9 +12,6 @@
 
 const Module = require('./Module');
 
-import type {TransformedCode} from '../JSTransformer/worker';
-import type {ReadResult} from './Module';
-
 class AssetModule extends Module {
   getPackage() {
     return null;
@@ -28,12 +25,12 @@ class AssetModule extends Module {
     return true;
   }
 
-  _finalizeReadResult(source: string, result: TransformedCode): ReadResult {
+  _readSourceCode() {
     // We do not want to return the "source code" of assets, since it's going to
     // be binary data and can potentially be very large. This source property
     // is only used to generate the sourcemaps (since we include all the
     // modules original sources in the sourcemaps).
-    return {...result, source: ''};
+    return '';
   }
 }
 
diff --git a/packages/metro/src/node-haste/Module.js b/packages/metro/src/node-haste/Module.js
index dac5a077..dc9ab582 100644
--- a/packages/metro/src/node-haste/Module.js
+++ b/packages/metro/src/node-haste/Module.js
@@ -10,26 +10,13 @@
 
 'use strict';
 
-const crypto = require('crypto');
-const docblock = require('jest-docblock');
 const fs = require('fs');
-const invariant = require('fbjs/lib/invariant');
 const isAbsolutePath = require('absolute-path');
-const jsonStableStringify = require('json-stable-stringify');
-const path = require('path');
 
 import type {
   TransformedCode,
   Options as WorkerOptions,
 } from '../JSTransformer/worker';
-import type {GlobalTransformCache} from '../lib/GlobalTransformCache';
-import type {
-  TransformCache,
-  GetTransformCacheKey,
-  ReadTransformProps,
-} from '../lib/TransformCaching';
-import type {Reporter} from '../lib/reporting';
-import type DependencyGraphHelpers from './DependencyGraph/DependencyGraphHelpers';
 import type ModuleCache from './ModuleCache';
 import type {LocalPath} from './lib/toLocalPath';
 import type {MetroSourceMapSegmentTuple} from 'metro-source-map';
@@ -49,67 +36,23 @@ export type TransformCode = (
   transformOptions: WorkerOptions,
 ) => Promise<TransformedCode>;
 
-export type HasteImpl = {
-  getHasteName(filePath: string): string | void,
-  // This exists temporarily to enforce consistency while we deprecate
-  // @providesModule.
-  enforceHasteNameMatches?: (
-    filePath: string,
-    expectedName: string | void,
-  ) => void,
-};
-
-export type Options = {
-  globalTransformCache: ?GlobalTransformCache,
-  hasteImplModulePath?: string,
-  reporter: Reporter,
-  resetCache: boolean,
-  transformCache: TransformCache,
-};
-
 export type ConstructorArgs = {
-  depGraphHelpers: DependencyGraphHelpers,
-  experimentalCaches: boolean,
   file: string,
-  getTransformCacheKey: GetTransformCacheKey,
   localPath: LocalPath,
   moduleCache: ModuleCache,
-  options: Options,
   transformCode: TransformCode,
 };
 
-type DocBlock = {+[key: string]: string};
-
 class Module {
   localPath: LocalPath;
   path: string;
   type: string;
 
-  _experimentalCaches: boolean;
-
   _moduleCache: ModuleCache;
   _transformCode: TransformCode;
-  _getTransformCacheKey: GetTransformCacheKey;
-  _depGraphHelpers: DependencyGraphHelpers;
-  _options: Options;
-
-  _docBlock: ?DocBlock;
-  _hasteNameCache: ?{+hasteName: ?string};
   _sourceCode: ?string;
-  _readPromises: Map<string, Promise<ReadResult>>;
 
-  _readResultsByOptionsKey: Map<string, CachedReadResult>;
-
-  constructor({
-    depGraphHelpers,
-    experimentalCaches,
-    file,
-    getTransformCacheKey,
-    localPath,
-    moduleCache,
-    options,
-    transformCode,
-  }: ConstructorArgs) {
+  constructor({file, localPath, moduleCache, transformCode}: ConstructorArgs) {
     if (!isAbsolutePath(file)) {
       throw new Error('Expected file to be absolute path but got ' + file);
     }
@@ -118,295 +61,59 @@ class Module {
     this.path = file;
     this.type = 'Module';
 
-    this._experimentalCaches = experimentalCaches;
-
     this._moduleCache = moduleCache;
     this._transformCode = transformCode;
-    this._getTransformCacheKey = getTransformCacheKey;
-    this._depGraphHelpers = depGraphHelpers;
-    this._options = options || {};
-
-    this._readPromises = new Map();
-    this._readResultsByOptionsKey = new Map();
   }
 
   isHaste(): boolean {
-    return this._getHasteName() != null;
+    return false;
   }
 
   getName(): string {
-    // TODO: T26134860 Used for debugging purposes only; disabled with the new
-    // caches.
-    if (this._experimentalCaches) {
-      return path.basename(this.path);
-    }
-
-    if (this.isHaste()) {
-      const name = this._getHasteName();
-      if (name != null) {
-        return name;
-      }
-    }
-
-    const p = this.getPackage();
-
-    if (!p) {
-      // Name is local path
-      return this.localPath;
-    }
-
-    const packageName = p.getName();
-    if (!packageName) {
-      return this.path;
-    }
-
-    return path
-      .join(packageName, path.relative(p.root, this.path))
-      .replace(/\\/g, '/');
+    return this.localPath;
   }
 
   getPackage() {
     return this._moduleCache.getPackageForModule(this);
   }
 
-  /**
-   * We don't need to invalidate the TranformCache itself because it guarantees
-   * itself that if a source code changed we won't return the cached transformed
-   * code.
-   */
   invalidate() {
     this._sourceCode = null;
-
-    // TODO: T26134860 Caches present in Module are not used with experimental
-    // caches, except for the one related to source code.
-    if (this._experimentalCaches) {
-      return;
-    }
-
-    this._readPromises.clear();
-    this._readResultsByOptionsKey.clear();
-    this._docBlock = null;
-    this._hasteNameCache = null;
   }
 
   _readSourceCode(): string {
     if (this._sourceCode == null) {
       this._sourceCode = fs.readFileSync(this.path, 'utf8');
     }
+
     return this._sourceCode;
   }
 
-  _readDocBlock(): DocBlock {
-    if (this._docBlock == null) {
-      this._docBlock = docblock.parse(docblock.extract(this._readSourceCode()));
-    }
-    return this._docBlock;
+  async read(transformOptions: WorkerOptions): Promise<ReadResult> {
+    const result: TransformedCode = await this._transformCode(
+      this,
+      null, // Source code is read on the worker
+      transformOptions,
+    );
+
+    const module = this;
+
+    return {
+      code: result.code,
+      dependencies: result.dependencies,
+      map: result.map,
+      get source() {
+        return module._readSourceCode();
+      },
+    };
   }
 
-  _getHasteName(): ?string {
-    if (this._hasteNameCache == null) {
-      this._hasteNameCache = {hasteName: this._readHasteName()};
-    }
-    return this._hasteNameCache.hasteName;
-  }
-
-  /**
-   * If a custom Haste implementation is provided, then we use it to determine
-   * the actual Haste name instead of "@providesModule".
-   * `enforceHasteNameMatches` has been added to that it is easier to
-   * transition from a system using "@providesModule" to a system using another
-   * custom system, by throwing if inconsistencies are detected. For example,
-   * we could verify that the file's basename (ex. "bar/foo.js") is the same as
-   * the "@providesModule" name (ex. "foo").
-   */
-  _readHasteName(): ?string {
-    const hasteImplModulePath = this._options.hasteImplModulePath;
-    if (hasteImplModulePath == null) {
-      return this._readHasteNameFromDocBlock();
-    }
-    // eslint-disable-next-line no-useless-call
-    const HasteImpl = (require.call(null, hasteImplModulePath): HasteImpl);
-    if (HasteImpl.enforceHasteNameMatches != null) {
-      const name = this._readHasteNameFromDocBlock();
-      HasteImpl.enforceHasteNameMatches(this.path, name || undefined);
-    }
-    return HasteImpl.getHasteName(this.path);
-  }
-
-  /**
-   * We extract the Haste name from the `@providesModule` docbloc field. This is
-   * not allowed for modules living in `node_modules`, except if they are
-   * whitelisted.
-   */
-  _readHasteNameFromDocBlock(): ?string {
-    const moduleDocBlock = this._readDocBlock();
-    const {providesModule} = moduleDocBlock;
-    if (providesModule && !this._depGraphHelpers.isNodeModulesDir(this.path)) {
-      return /^\S+/.exec(providesModule)[0];
-    }
+  readCached(transformOptions: WorkerOptions): null {
     return null;
   }
 
-  /**
-   * To what we read from the cache or worker, we need to add id and source.
-   */
-  _finalizeReadResult(source: string, result: TransformedCode): ReadResult {
-    return {...result, source};
-  }
-
-  async _transformCodeFor(
-    cacheProps: ReadTransformProps,
-  ): Promise<TransformedCode> {
-    const {_transformCode} = this;
-    invariant(_transformCode != null, 'missing code transform funtion');
-    const {sourceCode, transformOptions} = cacheProps;
-    return await _transformCode(this, sourceCode, transformOptions);
-  }
-
-  async _transformAndStoreCodeGlobally(
-    cacheProps: ReadTransformProps,
-    globalCache: GlobalTransformCache,
-  ): Promise<TransformedCode> {
-    const result = await this._transformCodeFor(cacheProps);
-    globalCache.store(globalCache.keyOf(cacheProps), result);
-    return result;
-  }
-
-  async _getTransformedCode(
-    cacheProps: ReadTransformProps,
-  ): Promise<TransformedCode> {
-    const globalCache = this._options.globalTransformCache;
-    if (globalCache == null || !globalCache.shouldFetch(cacheProps)) {
-      return await this._transformCodeFor(cacheProps);
-    }
-    const globalCachedResult = await globalCache.fetch(
-      globalCache.keyOf(cacheProps),
-    );
-    if (globalCachedResult != null) {
-      return globalCachedResult;
-    }
-    return await this._transformAndStoreCodeGlobally(cacheProps, globalCache);
-  }
-
-  async _getAndCacheTransformedCode(
-    cacheProps: ReadTransformProps,
-  ): Promise<TransformedCode> {
-    const result = await this._getTransformedCode(cacheProps);
-    this._options.transformCache.writeSync({...cacheProps, result});
-    return result;
-  }
-
-  /**
-   * Shorthand for reading both from cache or from fresh for all call sites that
-   * are asynchronous by default.
-   */
-  async read(transformOptions: WorkerOptions): Promise<ReadResult> {
-    // TODO: T26134860 Cache layer lives inside the transformer now; just call
-    // the transform method.
-    if (this._experimentalCaches) {
-      const result: TransformedCode = await this._transformCode(
-        this,
-        null, // Source code is read on the worker
-        transformOptions,
-      );
-
-      const module = this;
-
-      return {
-        code: result.code,
-        dependencies: result.dependencies,
-        map: result.map,
-        get source() {
-          return module._readSourceCode();
-        },
-      };
-    }
-
-    const cached = this.readCached(transformOptions);
-
-    if (cached != null) {
-      return cached;
-    }
-    return this.readFresh(transformOptions);
-  }
-
-  /**
-   * Same as `readFresh`, but reads from the cache instead of transforming
-   * the file from source. This has the benefit of being synchronous. As a
-   * result it is possible to read many cached Module in a row, synchronously.
-   */
-  readCached(transformOptions: WorkerOptions): CachedReadResult {
-    const key = stableObjectHash(transformOptions || {});
-    let result = this._readResultsByOptionsKey.get(key);
-    if (result != null) {
-      return result;
-    }
-    result = this._readFromTransformCache(transformOptions, key);
-    this._readResultsByOptionsKey.set(key, result);
-    return result;
-  }
-
-  /**
-   * Read again from the TransformCache, on disk. `readCached` should be favored
-   * so it's faster in case the results are already in memory.
-   */
-  _readFromTransformCache(
-    transformOptions: WorkerOptions,
-    transformOptionsKey: string,
-  ): CachedReadResult {
-    const cacheProps = this._getCacheProps(
-      transformOptions,
-      transformOptionsKey,
-    );
-    const cachedResult = this._options.transformCache.readSync(cacheProps);
-
-    if (cachedResult == null) {
-      return null;
-    }
-    return this._finalizeReadResult(cacheProps.sourceCode, cachedResult);
-  }
-
-  /**
-   * Gathers relevant data about a module: source code, transformed code,
-   * dependencies, etc. This function reads and transforms the source from
-   * scratch. We don't repeat the same work as `readCached` because we assume
-   * call sites have called it already.
-   */
   readFresh(transformOptions: WorkerOptions): Promise<ReadResult> {
-    const key = stableObjectHash(transformOptions || {});
-    const promise = this._readPromises.get(key);
-    if (promise != null) {
-      return promise;
-    }
-    const freshPromise = (async () => {
-      const cacheProps = this._getCacheProps(transformOptions, key);
-      const freshResult = await this._getAndCacheTransformedCode(cacheProps);
-      const finalResult = this._finalizeReadResult(
-        cacheProps.sourceCode,
-        freshResult,
-      );
-      this._readResultsByOptionsKey.set(key, finalResult);
-      return finalResult;
-    })();
-    this._readPromises.set(key, freshPromise);
-    return freshPromise;
-  }
-
-  _getCacheProps(transformOptions: WorkerOptions, transformOptionsKey: string) {
-    const sourceCode = this._readSourceCode();
-    const getTransformCacheKey = this._getTransformCacheKey;
-    return {
-      filePath: this.path,
-      localPath: this.localPath,
-      sourceCode,
-      getTransformCacheKey,
-      transformOptions,
-      transformOptionsKey,
-      cacheOptions: {
-        resetCache: this._options.resetCache,
-        reporter: this._options.reporter,
-      },
-    };
+    return this.read(transformOptions);
   }
 
   hash() {
@@ -422,19 +129,4 @@ class Module {
   }
 }
 
-// use weak map to speed up hash creation of known objects
-const knownHashes = new WeakMap();
-function stableObjectHash(object) {
-  let digest = knownHashes.get(object);
-  if (!digest) {
-    digest = crypto
-      .createHash('md5')
-      .update(jsonStableStringify(object))
-      .digest('base64');
-    knownHashes.set(object, digest);
-  }
-
-  return digest;
-}
-
 module.exports = Module;
diff --git a/packages/metro/src/node-haste/__tests__/Module-test.js b/packages/metro/src/node-haste/__tests__/Module-test.js
index 934e8688..73158df4 100644
--- a/packages/metro/src/node-haste/__tests__/Module-test.js
+++ b/packages/metro/src/node-haste/__tests__/Module-test.js
@@ -10,363 +10,94 @@
 
 'use strict';
 
-jest
-  .mock('fs', () => new (require('metro-memory-fs'))())
-  .mock('graceful-fs')
-  .mock('../ModuleCache')
-  .mock('../DependencyGraph/DependencyGraphHelpers')
-  .mock('../../lib/TransformCaching');
+jest.mock('fs').mock('../ModuleCache');
 
-const Module = require('../Module');
-const ModuleCache = require('../ModuleCache');
-const DependencyGraphHelpers = require('../DependencyGraph/DependencyGraphHelpers');
-const TransformCaching = require('../../lib/TransformCaching');
 const fs = require('fs');
-
-const packageJson = JSON.stringify({
-  name: 'arbitrary',
-  version: '1.0.0',
-  description: "A require('foo') story",
-});
-
-function mockPackageFile() {
-  fs.reset();
-  fs.mkdirSync('/root');
-  fs.writeFileSync('/root/package.json', packageJson);
-}
-
-function mockIndexFile(indexJs) {
-  fs.reset();
-  fs.mkdirSync('/root');
-  fs.writeFileSync('/root/index.js', indexJs);
-}
+const ModuleCache = require('../ModuleCache');
+const Module = require('../Module');
 
 describe('Module', () => {
-  const fileName = '/root/index.js';
+  let transformCode;
+  let moduleCache;
+  let module;
 
-  let cache;
-  const transformCache = TransformCaching.mocked();
-
-  const createCache = () => ({
-    get: jest
-      .genMockFn()
-      .mockImplementation((filepath, field, cb) => cb(filepath)),
-    invalidate: jest.genMockFn(),
-    end: jest.genMockFn(),
-  });
-
-  let transformCacheKey;
-  const createModule = options =>
-    new Module({
-      options: {transformCache},
-      transformCode: (module, sourceCode, transformOptions) => {
-        return Promise.resolve({code: sourceCode});
-      },
-      ...options,
-      cache,
-      file: (options && options.file) || fileName,
-      depGraphHelpers: new DependencyGraphHelpers(),
-      localPath: (options && options.localPath) || fileName,
-      moduleCache: new ModuleCache({cache}),
-      getTransformCacheKey: () => transformCacheKey,
+  beforeEach(() => {
+    transformCode = jest.fn().mockReturnValue({
+      code: 'int main(void) { return -1; }',
+      dependencies: ['stdlib.h', 'conio.h'],
+      map: [],
     });
 
-  const createJSONModule = options =>
-    createModule({...options, file: '/root/package.json'});
+    moduleCache = new ModuleCache();
 
-  beforeEach(function() {
-    Object.defineProperty(process, 'platform', {
-      configurable: true,
-      enumerable: true,
-      value: 'linux',
-    });
-    cache = createCache();
-    transformCacheKey = 'abcdef';
-    transformCache.mock.reset();
-  });
-
-  describe('Experimental caches', () => {
-    it('Calls into the transformer directly when having experimental caches on', async () => {
-      const transformCode = jest.fn().mockReturnValue({
-        code: 'code',
-        dependencies: ['dep1', 'dep2'],
-        map: [],
-      });
-
-      const module = new Module({
-        cache,
-        experimentalCaches: true,
-        depGraphHelpers: new DependencyGraphHelpers(),
-        file: fileName,
-        getTransformCacheKey: () => transformCacheKey,
-        localPath: fileName,
-        moduleCache: new ModuleCache({cache}),
-        options: {transformCache},
-        transformCode,
-      });
-
-      mockIndexFile('originalCode');
-      jest.spyOn(fs, 'readFileSync');
-
-      // Read the first time, transform code is called.
-      const res1 = await module.read({foo: 3});
-      expect(res1.code).toBe('code');
-      expect(res1.dependencies).toEqual(['dep1', 'dep2']);
-      expect(transformCode).toHaveBeenCalledTimes(1);
-
-      // Read a second time, transformCode is called again!
-      const res2 = await module.read({foo: 3});
-      expect(res2.code).toBe('code');
-      expect(res2.dependencies).toEqual(['dep1', 'dep2']);
-      expect(transformCode).toHaveBeenCalledTimes(2);
-
-      // Code was never read, though, because experimental caches read on the
-      // worker, to speed up local cache!
-      expect(fs.readFileSync).not.toHaveBeenCalled();
+    module = new Module({
+      file: '/root/to/file.js',
+      localPath: 'file.js',
+      moduleCache,
+      transformCode,
     });
   });
 
-  describe('Module ID', () => {
-    const moduleId = 'arbitraryModule';
-    const source = `/**
-       * @providesModule ${moduleId}
-       */
-    `;
+  afterEach(() => {
+    fs.readFileSync.mockReset();
+  });
 
-    let module;
-    beforeEach(() => {
-      module = createModule();
-    });
+  it('Returns the correct values for many properties and methods', () => {
+    expect(module.localPath).toBe('file.js');
+    expect(module.path).toBe('/root/to/file.js');
+    expect(module.type).toBe('Module');
 
-    describe('@providesModule annotations', () => {
-      beforeEach(() => {
-        mockIndexFile(source);
-      });
+    expect(module.hash()).toBeDefined();
+    expect(module.getName()).toBe('file.js');
+    expect(module.isHaste()).toBe(false);
+    expect(module.isAsset()).toBe(false);
+    expect(module.isPolyfill()).toBe(false);
+  });
 
-      it('extracts the module name from the header', () => {
-        expect(module.getName()).toEqual(moduleId);
-      });
+  it('reads the modules correctly', () => {
+    const opts = {};
 
-      it('identifies the module as haste module', () => {
-        expect(module.isHaste()).toBe(true);
-      });
+    // Caches are not in Module.js anymore.
+    expect(module.readCached()).toBe(null);
 
-      it('does not transform the file in order to access the name', () => {
-        const transformCode = jest
-          .genMockFn()
-          .mockReturnValue(Promise.resolve());
+    // When reading fresh, we call directly into read.
+    module.readFresh(opts);
+    expect(transformCode.mock.calls[0][0]).toBe(module);
+    expect(transformCode.mock.calls[0][1]).toBe(null);
+    expect(transformCode.mock.calls[0][2]).toBe(opts);
+  });
 
-        createModule({transformCode}).getName();
-        expect(transformCode).not.toBeCalled();
-      });
+  it('returns the result from the transform code straight away', async () => {
+    fs.readFileSync.mockReturnValue('original code');
 
-      it('does not transform the file in order to access the haste status', () => {
-        const transformCode = jest
-          .genMockFn()
-          .mockReturnValue(Promise.resolve());
-        createModule({transformCode}).isHaste();
-        expect(transformCode).not.toBeCalled();
-      });
-    });
-
-    describe('no annotation', () => {
-      beforeEach(() => {
-        mockIndexFile('arbitrary(code);');
-      });
-
-      it('uses the file name as module name', () => {
-        expect(module.getName()).toEqual(fileName);
-      });
-
-      it('does not identify the module as haste module', () =>
-        expect(module.isHaste()).toBe(false));
-
-      it('does not transform the file in order to access the name', () => {
-        const transformCode = jest
-          .genMockFn()
-          .mockReturnValue(Promise.resolve());
-
-        createModule({transformCode}).getName();
-        expect(transformCode).not.toBeCalled();
-      });
-
-      it('does not transform the file in order to access the haste status', () => {
-        const transformCode = jest
-          .genMockFn()
-          .mockReturnValue(Promise.resolve());
-        createModule({transformCode}).isHaste();
-        expect(transformCode).not.toBeCalled();
-      });
+    expect(await module.read({})).toEqual({
+      code: 'int main(void) { return -1; }',
+      dependencies: ['stdlib.h', 'conio.h'],
+      map: [],
+      source: 'original code',
     });
   });
 
-  describe('Code', () => {
-    const fileContents = 'arbitrary(code)';
-    beforeEach(function() {
-      mockIndexFile(fileContents);
-    });
+  it('checks that code is only read once until invalidated', async () => {
+    fs.readFileSync.mockReturnValue('original code');
 
-    it('exposes file contents as `code` property on the data exposed by `read()`', () =>
-      createModule()
-        .read()
-        .then(({code}) => expect(code).toBe(fileContents)));
-  });
+    // Read once. No access to "source", so no reads.
+    await module.read({});
+    expect(fs.readFileSync).toHaveBeenCalledTimes(0);
 
-  describe('Custom Code Transform', () => {
-    let transformCode;
-    let transformResult;
-    const fileContents = 'arbitrary(code);';
-    const exampleCode = `
-      ${'require'}('a');
-      ${'System.import'}('b');
-      ${'require'}('c');`;
+    // Read again, accessing "source".
+    expect((await module.read({})).source).toEqual('original code');
+    expect(fs.readFileSync).toHaveBeenCalledTimes(1);
 
-    beforeEach(function() {
-      transformResult = {code: ''};
-      transformCode = jest
-        .genMockFn()
-        .mockImplementation((module, sourceCode, options) => {
-          transformCache.writeSync({
-            filePath: module.path,
-            sourceCode,
-            transformOptions: options,
-            getTransformCacheKey: () => transformCacheKey,
-            result: transformResult,
-          });
-          return Promise.resolve(transformResult);
-        });
-      mockIndexFile(fileContents);
-    });
+    // Read again, accessing "source" again. Still 1 because code was cached.
+    expect((await module.read({})).source).toEqual('original code');
+    expect(fs.readFileSync).toHaveBeenCalledTimes(1);
 
-    it('passes the module and file contents to the transform function when reading', () => {
-      const module = createModule({transformCode});
-      return module.read().then(() => {
-        expect(transformCode).toBeCalledWith(module, fileContents, undefined);
-      });
-    });
+    // Invalidate.
+    module.invalidate();
 
-    it('passes any additional options to the transform function when reading', () => {
-      const module = createModule({transformCode});
-      const transformOptions = {arbitrary: Object()};
-      return module
-        .read(transformOptions)
-        .then(() =>
-          expect(transformCode.mock.calls[0][2]).toBe(transformOptions),
-        );
-    });
-
-    it('passes the module and file contents to the transform for JSON files', () => {
-      mockPackageFile();
-      const module = createJSONModule({transformCode});
-      return module.read().then(() => {
-        expect(transformCode).toBeCalledWith(module, packageJson, undefined);
-      });
-    });
-
-    it('does not extend the passed options object for JSON files', () => {
-      mockPackageFile();
-      const module = createJSONModule({transformCode});
-      const options = {arbitrary: 'foo'};
-      return module.read(options).then(() => {
-        expect(transformCode).toBeCalledWith(module, packageJson, options);
-      });
-    });
-
-    it('uses dependencies that `transformCode` resolves to, instead of extracting them', async () => {
-      const mockedDependencies = ['foo', 'bar'];
-      transformResult = {
-        code: exampleCode,
-        dependencies: mockedDependencies,
-      };
-      const module = createModule({transformCode});
-      const data = await module.read();
-
-      expect(data.dependencies).toEqual(mockedDependencies);
-    });
-
-    it('forwards all additional properties of the result provided by `transformCode`', () => {
-      transformResult = {
-        code: exampleCode,
-        arbitrary: 'arbitrary',
-        dependencyOffsets: [12, 764],
-        map: {version: 3},
-        subObject: {foo: 'bar'},
-      };
-      const module = createModule({transformCode});
-
-      return module.read().then(result => {
-        expect(result).toEqual(jasmine.objectContaining(transformResult));
-      });
-    });
-
-    it('exposes the transformed code rather than the raw file contents', async () => {
-      transformResult = {code: exampleCode};
-      const module = createModule({transformCode});
-      const data = await module.read();
-
-      expect(data.code).toBe(exampleCode);
-    });
-
-    it('exposes the raw file contents as `source` property', () => {
-      const module = createModule({transformCode});
-      return module.read().then(data => expect(data.source).toBe(fileContents));
-    });
-
-    it('exposes a source map returned by the transform', async () => {
-      const map = {version: 3};
-      transformResult = {map, code: exampleCode};
-      const module = createModule({transformCode});
-      const data = await module.read();
-
-      expect(data.map).toBe(map);
-    });
-
-    it('caches the transform result for the same transform options', () => {
-      let module = createModule({transformCode});
-      return module.read().then(() => {
-        expect(transformCode).toHaveBeenCalledTimes(1);
-        // We want to check transform caching rather than shallow caching of
-        // Promises returned by read().
-        module = createModule({transformCode});
-        return module.read().then(() => {
-          expect(transformCode).toHaveBeenCalledTimes(1);
-        });
-      });
-    });
-
-    it('triggers a new transform for different transform options', () => {
-      const module = createModule({transformCode});
-      return module.read({foo: 1}).then(() => {
-        expect(transformCode).toHaveBeenCalledTimes(1);
-        return module.read({foo: 2}).then(() => {
-          expect(transformCode).toHaveBeenCalledTimes(2);
-        });
-      });
-    });
-
-    it('triggers a new transform for different source code', () => {
-      let module = createModule({transformCode});
-      return module.read().then(() => {
-        expect(transformCode).toHaveBeenCalledTimes(1);
-        cache = createCache();
-        mockIndexFile('test');
-        module = createModule({transformCode});
-        return module.read().then(() => {
-          expect(transformCode).toHaveBeenCalledTimes(2);
-        });
-      });
-    });
-
-    it('triggers a new transform for different transform cache key', () => {
-      let module = createModule({transformCode});
-      return module.read().then(() => {
-        expect(transformCode).toHaveBeenCalledTimes(1);
-        transformCacheKey = 'other';
-        module = createModule({transformCode});
-        return module.read().then(() => {
-          expect(transformCode).toHaveBeenCalledTimes(2);
-        });
-      });
-    });
+    // Read again, this time it will read it.
+    expect((await module.read({})).source).toEqual('original code');
+    expect(fs.readFileSync).toHaveBeenCalledTimes(2);
   });
 });