diff --git a/README.md b/README.md
index 2cdbd63e4b..65adcf94a4 100644
--- a/README.md
+++ b/README.md
@@ -110,12 +110,12 @@ Compile and run `test.js`.
 ```javascript
 var to5 = require("6to5");
 
-to5.transform("code();", options);
+to5.transform("code();", options).code;
 
-to5.transformFileSync("filename.js", options);
-
-to5.transformFile("filename.js", options, function (err, data) {
+to5.transformFileSync("filename.js", options).code;
 
+to5.transformFile("filename.js", options, function (err, result) {
+  result.code;
 });
 ```
 
@@ -132,12 +132,10 @@ to5.transformFile("filename.js", options, function (err, data) {
   // See `blacklist` for naming scheme.
   whitelist: [],
 
-  // Append source map and comment to bottom of returned output.
+  // If truthy, adds a `map` property to returned output.
+  // If set to "comment", the sourceMappingURL directive is added at the bottom
   sourceMap: false,
 
-  // Returns an object `{ code: "", map: {} }` instead of an appended string.
-  sourceMapObject: false,
-
   // Filename for use in errors etc.
   filename: "unknown",
 
diff --git a/bin/6to5 b/bin/6to5
index 752959da34..095ce1de96 100755
--- a/bin/6to5
+++ b/bin/6to5
@@ -9,7 +9,7 @@ var to5       = require("../lib/6to5/node");
 var fs        = require("fs");
 var _         = require("lodash");
 
-commander.option("-c, --source-maps-comment", "Generate source map and append it with a sourceMappingURL comment alongside the compiled output");
+commander.option("-t, --source-map-type [type]", "Specify a custom sourcemap type such as `comment`");
 commander.option("-s, --source-maps", "Save source map alongside the compiled code when using --out-file and --out-dir flags");
 //commander.option("-w, --watch", "Watch, only works with --out-dir");
 
@@ -58,7 +58,7 @@ var readdirFilter = function (filename) {
 var mainOpts = {
   blacklist: commander.blacklist,
   whitelist: commander.whitelist,
-  sourceMap: commander.sourceMapsComment || commander.sourceMaps,
+  sourceMap: commander.sourceMapType || commander.sourceMaps,
   tolerant:  commander.tolerant
 };
 
@@ -73,10 +73,6 @@ var compile = function (filename) {
 };
 
 if (commander.outDir) {
-  if (commander.sourceMaps) {
-    mainOpts.sourceMapObject = true;
-  }
-
   var write = function (src, relative) {
     var data = compile(src);
 
@@ -85,12 +81,11 @@ if (commander.outDir) {
     var up = path.normalize(dest + "/..");
     mkdirp.sync(up);
 
-    if (mainOpts.sourceMapObject) {
+    if (commander.sourceMaps && !commander.sourceMapType) {
       fs.writeFileSync(dest + ".map", data.map.toJSON());
-      data = data.code;
     }
 
-    fs.writeFileSync(dest, data);
+    fs.writeFileSync(dest, data.code);
 
     console.log(src + " -> " + dest);
   };
@@ -130,7 +125,7 @@ if (commander.outDir) {
   });
 
   _.each(filenames, function (filename) {
-    data.push(compile(filename) + "\n");
+    data.push(compile(filename).code + "\n");
   });
 
   data = data.join("");
diff --git a/bin/6to5-node b/bin/6to5-node
index e862736934..d1180ae02b 100755
--- a/bin/6to5-node
+++ b/bin/6to5-node
@@ -26,7 +26,7 @@ var _eval = function (code, filename) {
 };
 
 if (commander.eval) {
-  var code = to5.transform(commander.eval, { filename: "eval" });
+  var code = to5.transform(commander.eval, { filename: "eval" }).code;
 
   var result = _eval(code, "eval");
   if (commander.print) console.log(result);
@@ -58,7 +58,7 @@ function replEval(code, context, filename, callback) {
 
   try {
     code = code.slice(1, -2); // remove "(" and "\n)"
-    code = to5.transform(code, { filename: filename });
+    code = to5.transform(code, { filename: filename }).code;
 
     result = vm.runInThisContext(code, filename);
   } catch (e) {
diff --git a/lib/6to5/node.js b/lib/6to5/node.js
index 6818a153c2..6b53d00cd3 100644
--- a/lib/6to5/node.js
+++ b/lib/6to5/node.js
@@ -18,18 +18,18 @@ exports.transformFile = function (filename, opts, callback) {
 
   opts.filename = filename;
 
-  fs.readFile(filename, function (err, raw) {
+  fs.readFile(filename, function (err, code) {
     if (err) return callback(err);
 
-    var code;
+    var result;
 
     try {
-      code = transform(raw, opts);
+      result = transform(code, opts);
     } catch (err) {
       return callback(err);
     }
 
-    callback(null, code);
+    callback(null, result);
   });
 };
 
diff --git a/lib/6to5/transform.js b/lib/6to5/transform.js
index 50ce6accb9..b25c48fb00 100644
--- a/lib/6to5/transform.js
+++ b/lib/6to5/transform.js
@@ -9,16 +9,13 @@ var transform = module.exports = function (code, opts) {
   code = (code || "") + "";
 
   _.defaults(opts, {
-    sourceMapObject: false,
-    blacklist:       [],
-    whitelist:       [],
-    sourceMap:       false,
-    filename:        "unknown",
-    format:          {}
+    blacklist: [],
+    whitelist: [],
+    sourceMap: false,
+    filename:  "unknown",
+    format:    {}
   });
 
-  if (opts.sourceMapObject) opts.sourceMap = true;
-
   return util.parse(opts.filename, code, function (tree) {
     return transform._run(code, tree, opts);
   });
@@ -44,11 +41,12 @@ transform._run = function (code, tree, opts) {
   });
 
   var genOpts = {
+    file: path.basename(opts.filename),
     format: opts.format
   };
 
   if (opts.sourceMap) {
-    genOpts.sourceMap = path.basename(opts.filename);
+    genOpts.sourceMap = genOpts.file;
     genOpts.sourceContent = code;
     genOpts.sourceMapWithCode = true;
   }
@@ -56,13 +54,13 @@ transform._run = function (code, tree, opts) {
   var result = util.generate(tree, genOpts);
 
   if (opts.sourceMap) {
-    if (opts.sourceMapObject) {
-      return result;
-    } else {
-      return result.code + "\n" + util.sourceMapToComment(result.map) + "\n";
+    if (opts.sourceMap === "comment") {
+      result.code += "\n" + util.sourceMapToComment(result.map);
     }
+
+    return result;
   } else {
-    return result + "\n";
+    return { code: result, map: null };
   }
 };
 
@@ -82,7 +80,7 @@ transform.test = function (actual, expect, opts) {
   _.defaults(opts, { filename: "test" });
 
   var actualCode = actual.code.trim();
-  var transformedCode = transform(actualCode, opts);
+  var transformedCode = transform(actualCode, opts).code;
   var actualAst = util.parse(actual.filename, transformedCode);
   actualCode = util.generate(actualAst);