diff --git a/packages/core/integration-tests/test/integration/ts-types/augmentation/augmenter/package.json b/packages/core/integration-tests/test/integration/ts-types/augmentation/augmenter/package.json
new file mode 100644
index 00000000000..9be8a41e23e
--- /dev/null
+++ b/packages/core/integration-tests/test/integration/ts-types/augmentation/augmenter/package.json
@@ -0,0 +1,10 @@
+{
+	"name": "augmenter",
+	"version": "1.0.0",
+	"source": "src/index.ts",
+	"types": "dist/index.d.ts",
+	"main": "dist/index.js",
+	"dependencies": {
+		"original": "1.0.0"
+	}
+}
diff --git a/packages/core/integration-tests/test/integration/ts-types/augmentation/augmenter/src/expected.d.ts b/packages/core/integration-tests/test/integration/ts-types/augmentation/augmenter/src/expected.d.ts
new file mode 100644
index 00000000000..b408dfa3fe9
--- /dev/null
+++ b/packages/core/integration-tests/test/integration/ts-types/augmentation/augmenter/src/expected.d.ts
@@ -0,0 +1,9 @@
+export const anotherThing: string;
+declare module "original" {
+    interface Person {
+        greet(): string;
+    }
+}
+export const somethingElse: string;
+
+//# sourceMappingURL=index.d.ts.map
diff --git a/packages/core/integration-tests/test/integration/ts-types/augmentation/augmenter/src/index.ts b/packages/core/integration-tests/test/integration/ts-types/augmentation/augmenter/src/index.ts
new file mode 100644
index 00000000000..a4b42add7e0
--- /dev/null
+++ b/packages/core/integration-tests/test/integration/ts-types/augmentation/augmenter/src/index.ts
@@ -0,0 +1,12 @@
+import { Person } from "original";
+Person.prototype.greet = function() { return `Hello ${this.name}!` }
+
+export const anotherThing: string = "hello";
+
+declare module "original" {
+  interface Person {
+    greet(): string;
+  }
+}
+
+export const somethingElse: string = "goodbye";
\ No newline at end of file
diff --git a/packages/core/integration-tests/test/integration/ts-types/augmentation/original/built-src/index.d.ts b/packages/core/integration-tests/test/integration/ts-types/augmentation/original/built-src/index.d.ts
new file mode 100644
index 00000000000..92fb12cd0d0
--- /dev/null
+++ b/packages/core/integration-tests/test/integration/ts-types/augmentation/original/built-src/index.d.ts
@@ -0,0 +1,4 @@
+export declare class Person {
+    name: string;
+    constructor(name: string);
+}
diff --git a/packages/core/integration-tests/test/integration/ts-types/augmentation/original/built-src/index.js b/packages/core/integration-tests/test/integration/ts-types/augmentation/original/built-src/index.js
new file mode 100644
index 00000000000..de87b1fd3b5
--- /dev/null
+++ b/packages/core/integration-tests/test/integration/ts-types/augmentation/original/built-src/index.js
@@ -0,0 +1,9 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.Person = void 0;
+class Person {
+    constructor(name) {
+        this.name = name;
+    }
+}
+exports.Person = Person;
diff --git a/packages/core/integration-tests/test/integration/ts-types/augmentation/original/package.json b/packages/core/integration-tests/test/integration/ts-types/augmentation/original/package.json
new file mode 100644
index 00000000000..5137c43d6c4
--- /dev/null
+++ b/packages/core/integration-tests/test/integration/ts-types/augmentation/original/package.json
@@ -0,0 +1,7 @@
+{
+	"name": "original",
+	"version": "1.0.0",
+	"source": "src/index.ts",
+	"main": "built-src/index.js",
+    "types": "built-src/index.d.ts"
+}
diff --git a/packages/core/integration-tests/test/integration/ts-types/augmentation/original/src/index.ts b/packages/core/integration-tests/test/integration/ts-types/augmentation/original/src/index.ts
new file mode 100644
index 00000000000..e99d9ddf2d3
--- /dev/null
+++ b/packages/core/integration-tests/test/integration/ts-types/augmentation/original/src/index.ts
@@ -0,0 +1,3 @@
+export class Person {
+    constructor(public name: string) {}
+}
\ No newline at end of file
diff --git a/packages/core/integration-tests/test/integration/ts-types/augmentation/package.json b/packages/core/integration-tests/test/integration/ts-types/augmentation/package.json
new file mode 100644
index 00000000000..90a0e144830
--- /dev/null
+++ b/packages/core/integration-tests/test/integration/ts-types/augmentation/package.json
@@ -0,0 +1,7 @@
+{
+	"private": true,
+	"workspaces": [
+		"augmenter",
+		"original"
+	]
+}
diff --git a/packages/core/integration-tests/test/integration/ts-types/augmentation/yarn.lock b/packages/core/integration-tests/test/integration/ts-types/augmentation/yarn.lock
new file mode 100644
index 00000000000..fb57ccd13af
--- /dev/null
+++ b/packages/core/integration-tests/test/integration/ts-types/augmentation/yarn.lock
@@ -0,0 +1,4 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
diff --git a/packages/core/integration-tests/test/ts-types.js b/packages/core/integration-tests/test/ts-types.js
index b06890f96ed..7f57f6bcf9b 100644
--- a/packages/core/integration-tests/test/ts-types.js
+++ b/packages/core/integration-tests/test/ts-types.js
@@ -323,4 +323,42 @@ describe('typescript types', function () {
     );
     assert.equal(dist, expected);
   });
+
+  it('should work with module augmentation', async function () {
+    let fixtureDir = path.join(__dirname, 'integration/ts-types/augmentation');
+    await outputFS.mkdirp(path.join(fixtureDir, 'node_modules'));
+    await ncp(fixtureDir, fixtureDir);
+    await outputFS.symlink(
+      path.join(fixtureDir, 'original'),
+      path.join(fixtureDir, 'node_modules/original'),
+    );
+
+    let b = await bundle(path.join(fixtureDir, 'augmenter'), {
+      inputFS: overlayFS,
+    });
+    assertBundles(b, [
+      {
+        name: 'index.js',
+        type: 'js',
+        assets: ['index.ts'],
+      },
+      {
+        name: 'index.d.ts',
+        type: 'ts',
+        assets: ['index.ts'],
+      },
+    ]);
+
+    let dist = (
+      await outputFS.readFile(
+        path.join(fixtureDir, 'augmenter/dist/index.d.ts'),
+        'utf8',
+      )
+    ).replace(/\r\n/g, '\n');
+    let expected = await inputFS.readFile(
+      path.join(fixtureDir, 'augmenter/src/expected.d.ts'),
+      'utf8',
+    );
+    assert.equal(dist, expected);
+  });
 });
diff --git a/packages/transformers/typescript-types/src/collect.js b/packages/transformers/typescript-types/src/collect.js
index e337ac2f29b..ac3bf7fb7fe 100644
--- a/packages/transformers/typescript-types/src/collect.js
+++ b/packages/transformers/typescript-types/src/collect.js
@@ -11,6 +11,9 @@ export function collect(
   context: any,
   sourceFile: any,
 ): any {
+  // When module definitions are nested inside each other (e.g with module augmentation),
+  // we want to keep track of the hierarchy so we can associated nodes with the right module.
+  const moduleStack: Array<?TSModule> = [];
   let _currentModule: ?TSModule;
   let visit = (node: any): any => {
     if (ts.isBundle(node)) {
@@ -18,6 +21,7 @@ export function collect(
     }
 
     if (ts.isModuleDeclaration(node)) {
+      moduleStack.push(_currentModule);
       _currentModule = new TSModule();
       moduleGraph.addModule(node.name.text, _currentModule);
     }
@@ -105,7 +109,13 @@ export function collect(
       }
     }
 
-    return ts.visitEachChild(node, visit, context);
+    const results = ts.visitEachChild(node, visit, context);
+    // After we finish traversing the children of a module definition,
+    // we need to make sure that subsequent nodes get associated with the next-highest level module.
+    if (ts.isModuleDeclaration(node)) {
+      _currentModule = moduleStack.pop();
+    }
+    return results;
   };
 
   return ts.visitNode(sourceFile, visit);
diff --git a/packages/transformers/typescript-types/src/shake.js b/packages/transformers/typescript-types/src/shake.js
index bbb4dd7311d..4bab766885f 100644
--- a/packages/transformers/typescript-types/src/shake.js
+++ b/packages/transformers/typescript-types/src/shake.js
@@ -19,6 +19,12 @@ export function shake(
   // Propagate exports from the main module to determine what types should be included
   let exportedNames = moduleGraph.propagate(context);
 
+  // When module definitions are nested inside each other (e.g with module augmentation),
+  // we want to keep track of the hierarchy so we can associated nodes with the right module.
+  const moduleStack: Array<?TSModule> = [];
+
+  let addedGeneratedImports = false;
+
   let _currentModule: ?TSModule;
   let visit = (node: any): any => {
     if (ts.isBundle(node)) {
@@ -27,12 +33,22 @@ export function shake(
 
     // Flatten all module declarations into the top-level scope
     if (ts.isModuleDeclaration(node)) {
+      // Deeply nested module declarations are assumed to be module augmentations and left alone.
+      if (moduleStack.length >= 1) {
+        // Since we are hoisting them to the top-level scope, we need to add a "declare" keyword to make them ambient.
+        node.modifiers.unshift(ts.createModifier(ts.SyntaxKind.DeclareKeyword));
+        return node;
+      }
+
+      moduleStack.push(_currentModule);
       let isFirstModule = !_currentModule;
       _currentModule = moduleGraph.getModule(node.name.text);
       let statements = ts.visitEachChild(node, visit, context).body.statements;
+      _currentModule = moduleStack.pop();
 
-      if (isFirstModule) {
+      if (isFirstModule && !addedGeneratedImports) {
         statements.unshift(...generateImports(moduleGraph));
+        addedGeneratedImports = true;
       }
 
       return statements;