diff --git a/packages/babel-generator/README.md b/packages/babel-generator/README.md
index 0164d55c2e..aeab598579 100644
--- a/packages/babel-generator/README.md
+++ b/packages/babel-generator/README.md
@@ -44,4 +44,41 @@ name                   | type     | default         | description
 sourceMaps             | boolean  | `false`         | Enable generating source maps
 sourceMapTarget        | string   |                 | The filename of the generated code that the source map will be associated with
 sourceRoot             | string   |                 | A root for all relative URLs in the source map
-sourceFileName         | string   |                 | The filename for the source code (i.e. the code in the `code` argument)
+sourceFileName         | string   |                 | The filename for the source code (i.e. the code in the `code` argument).  This will only be used if `code` is a string.
+
+## AST from Multiple Sources
+
+In most cases, Babel does a 1:1 transformation of input-file to output-file.  However,
+you may be dealing with AST constructed from multiple sources - JS files, templates, etc.
+If this is the case, and you want the sourcemaps to reflect the correct sources, you'll need
+to make some changes to your code.
+
+First, each node with a `loc` property (which indicates that node's original placement in the
+source document) must also include a `loc.filename` property, set to the source filename.
+
+Second, you should pass an object to `generate` as the `code` parameter.  Keys
+should be the source filenames, and values should be the source content.
+
+Here's an example of what that might look like:
+
+```js
+import {parse} from 'babylon';
+import traverse from "babel-traverse";
+import generate from 'babel-generator';
+
+const a = 'var a = 1;';
+const b = 'var b = 2;';
+const astA = parse(a, { filename: 'a.js' });
+const astB = parse(b, { filename: 'b.js' });
+const ast = {
+  type: 'Program',
+  body: [].concat(astA.body, ast2.body)
+};
+
+const { code, map } = generate(ast, { /* options */ }, {
+  'a.js': a,
+  'b.js': b
+});
+
+// Sourcemap will point to both a.js and b.js where appropriate.
+```
diff --git a/packages/babel-generator/src/index.js b/packages/babel-generator/src/index.js
index f65d065520..9c4e08672d 100644
--- a/packages/babel-generator/src/index.js
+++ b/packages/babel-generator/src/index.js
@@ -71,7 +71,7 @@ export class CodeGenerator extends Printer {
 
   static normalizeOptions(code, opts, tokens) {
     let style = "  ";
-    if (code) {
+    if (code && typeof code === "string") {
       let indent = detectIndent(code).indent;
       if (indent && indent !== " ") style = indent;
     }
diff --git a/packages/babel-generator/src/source-map.js b/packages/babel-generator/src/source-map.js
index 942f931b9f..beea55bddf 100644
--- a/packages/babel-generator/src/source-map.js
+++ b/packages/babel-generator/src/source-map.js
@@ -17,7 +17,13 @@ export default class SourceMap {
         sourceRoot: opts.sourceRoot
       });
 
-      this.map.setSourceContent(opts.sourceFileName, code);
+      if (typeof code === "string") {
+        this.map.setSourceContent(opts.sourceFileName, code);
+      } else if (typeof code === "object") {
+        Object.keys(code).forEach((sourceFileName) => {
+          this.map.setSourceContent(sourceFileName, code[sourceFileName]);
+        });
+      }
     } else {
       this.map = null;
     }
@@ -68,7 +74,7 @@ export default class SourceMap {
     }
 
     this.last = {
-      source: this.opts.sourceFileName,
+      source: loc.filename || this.opts.sourceFileName,
       generated: generated,
       original: original
     };
diff --git a/packages/babel-generator/test/index.js b/packages/babel-generator/test/index.js
index e6cfc39827..7ee494b75d 100644
--- a/packages/babel-generator/test/index.js
+++ b/packages/babel-generator/test/index.js
@@ -17,6 +17,44 @@ suite("generation", function () {
       assert.ok(t.VISITOR_KEYS[type], type + " should not exist");
     });
   });
+
+  test("multiple sources", function () {
+    var sources = {
+      "a.js": "function hi (msg) { console.log(msg); }\n",
+      "b.js": "hi('hello');\n"
+    };
+    var parsed = _.keys(sources).reduce(function (_parsed, filename) {
+      _parsed[filename] = parse(sources[filename], { sourceFilename: filename });
+      return _parsed;
+    }, {});
+
+    var combinedAst = {
+      "type": "File",
+      "program": {
+        "type": "Program",
+        "sourceType": "module",
+        "body": [].concat(parsed["a.js"].program.body, parsed["b.js"].program.body)
+      }
+    };
+
+    var generated = generate.default(combinedAst, { sourceMaps: true }, sources);
+
+    chai.expect(generated.map).to.deep.equal({
+      version: 3,
+      sources: [ 'a.js', 'b.js' ],
+      names: [],
+      mappings: 'AAAA,SAAS,EAAT,CAAa,GAAb,EAAkB;AAAE,UAAQ,GAAR,CAAY,GAAZ,EAAF;CAAlB;;GCAG,OAAH',
+      sourcesContent: [
+      'function hi (msg) { console.log(msg); }\n',
+        'hi(\'hello\');\n'
+      ]
+    }, "sourcemap was incorrectly generated");
+
+    chai.expect(generated.code).to.equal(
+      "function hi(msg) {\n  console.log(msg);\n}\n\nhi('hello');",
+      "code was incorrectly generated"
+    );
+  });
 });
 
 
diff --git a/packages/babylon/README.md b/packages/babylon/README.md
index 8c927de516..d5833e498c 100644
--- a/packages/babylon/README.md
+++ b/packages/babylon/README.md
@@ -37,6 +37,8 @@ Significant diversions are expected to occur in the future such as streaming, EB
 - **sourceType**: Indicate the mode the code should be parsed in. Can be
   either `"script"` or `"module"`.
 
+- **sourceFilename**: Correlate output AST nodes with their source filename.  Useful when generating code and source maps from the ASTs of multiple input files.
+
 - **plugins**: Array containing the plugins that you want to enable.
 
 ### Example
diff --git a/packages/babylon/src/options.js b/packages/babylon/src/options.js
index 9da58e93b5..59bd2d35d7 100755
--- a/packages/babylon/src/options.js
+++ b/packages/babylon/src/options.js
@@ -3,6 +3,7 @@
 
 export const defaultOptions: {
   sourceType: string,
+  sourceFilename: any,
   allowReturnOutsideFunction: boolean,
   allowImportExportEverywhere: boolean,
   allowSuperOutsideMethod: boolean,
@@ -11,6 +12,8 @@ export const defaultOptions: {
 } = {
   // Source type ("script" or "module") for different semantics
   sourceType: "script",
+  // Source filename.
+  sourceFilename: undefined,
   // When enabled, a return at the top level is not considered an
   // error.
   allowReturnOutsideFunction: false,
diff --git a/packages/babylon/src/parser/index.js b/packages/babylon/src/parser/index.js
index 3db3c56984..8b3353bed0 100644
--- a/packages/babylon/src/parser/index.js
+++ b/packages/babylon/src/parser/index.js
@@ -14,6 +14,7 @@ export default class Parser extends Tokenizer {
     this.isReservedWord = reservedWords[6];
     this.input = input;
     this.plugins = this.loadPlugins(this.options.plugins);
+    this.filename = options.sourceFilename;
 
     // If enabled, skip leading hashbang line.
     if (this.state.pos === 0 && this.input[0] === "#" && this.input[1] === "!") {
diff --git a/packages/babylon/src/parser/node.js b/packages/babylon/src/parser/node.js
index d9e07ae329..fa44f561c4 100644
--- a/packages/babylon/src/parser/node.js
+++ b/packages/babylon/src/parser/node.js
@@ -6,11 +6,12 @@ import { SourceLocation } from "../util/location";
 const pp = Parser.prototype;
 
 class Node {
-  constructor(pos?: number, loc?: SourceLocation) {
+  constructor(pos?: number, loc?: SourceLocation, filename?: string) {
     this.type = "";
     this.start = pos;
     this.end = 0;
     this.loc = new SourceLocation(loc);
+    if (filename) this.loc.filename = filename;
   }
 
   type: string;
@@ -26,11 +27,11 @@ class Node {
 }
 
 pp.startNode = function () {
-  return new Node(this.state.start, this.state.startLoc);
+  return new Node(this.state.start, this.state.startLoc, this.filename);
 };
 
 pp.startNodeAt = function (pos, loc) {
-  return new Node(pos, loc);
+  return new Node(pos, loc, this.filename);
 };
 
 function finishNodeAt(node, type, pos, loc) {
diff --git a/packages/babylon/test/fixtures/core/categorized/filename-specified/actual.js b/packages/babylon/test/fixtures/core/categorized/filename-specified/actual.js
new file mode 100644
index 0000000000..76e45db756
--- /dev/null
+++ b/packages/babylon/test/fixtures/core/categorized/filename-specified/actual.js
@@ -0,0 +1 @@
+var node = "shouldHaveFilenameLocProp";
diff --git a/packages/babylon/test/fixtures/core/categorized/filename-specified/expected.json b/packages/babylon/test/fixtures/core/categorized/filename-specified/expected.json
new file mode 100644
index 0000000000..9b5ba11fa1
--- /dev/null
+++ b/packages/babylon/test/fixtures/core/categorized/filename-specified/expected.json
@@ -0,0 +1,109 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 39,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 39
+    },
+    "filename": "path/to/input-file.js"
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 39,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 1,
+        "column": 39
+      },
+      "filename": "path/to/input-file.js"
+    },
+    "sourceType": "script",
+    "body": [
+      {
+        "type": "VariableDeclaration",
+        "start": 0,
+        "end": 39,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 39
+          },
+          "filename": "path/to/input-file.js"
+        },
+        "declarations": [
+          {
+            "type": "VariableDeclarator",
+            "start": 4,
+            "end": 38,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 4
+              },
+              "end": {
+                "line": 1,
+                "column": 38
+              },
+              "filename": "path/to/input-file.js"
+            },
+            "id": {
+              "type": "Identifier",
+              "start": 4,
+              "end": 8,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 4
+                },
+                "end": {
+                  "line": 1,
+                  "column": 8
+                },
+                "filename": "path/to/input-file.js"
+              },
+              "name": "node"
+            },
+            "init": {
+              "type": "StringLiteral",
+              "start": 11,
+              "end": 38,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 11
+                },
+                "end": {
+                  "line": 1,
+                  "column": 38
+                },
+                "filename": "path/to/input-file.js"
+              },
+              "extra": {
+                "rawValue": "shouldHaveFilenameLocProp",
+                "raw": "\"shouldHaveFilenameLocProp\""
+              },
+              "value": "shouldHaveFilenameLocProp"
+            }
+          }
+        ],
+        "kind": "var"
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babylon/test/fixtures/core/categorized/filename-specified/options.json b/packages/babylon/test/fixtures/core/categorized/filename-specified/options.json
new file mode 100644
index 0000000000..400e29986a
--- /dev/null
+++ b/packages/babylon/test/fixtures/core/categorized/filename-specified/options.json
@@ -0,0 +1,3 @@
+{
+  "sourceFilename": "path/to/input-file.js"
+}
\ No newline at end of file