diff --git a/build/helper.js b/build/helper.js
index b93b17bca..e58077012 100644
--- a/build/helper.js
+++ b/build/helper.js
@@ -146,10 +146,11 @@ exports.travelSrcDir = function (srcDir, cb) {
  * @param {string} [opt]
  * @param {string} [opt.inputPath] Absolute input path.
  * @param {string} [opt.outputPath] Absolute output path.
+ * @param {string} [opt.preamble]
  * @param {Function} [opt.transform]
  * @param {Function} [opt.reserveDEV]
  */
-exports.prePulishSrc = function ({inputPath, outputPath, transform, reserveDEV}) {
+exports.prePulishSrc = function ({inputPath, outputPath, preamble, transform, reserveDEV}) {
     assert(inputPath && outputPath);
 
     console.log(
@@ -173,6 +174,10 @@ exports.prePulishSrc = function ({inputPath, outputPath, transform, reserveDEV})
         code = transform({code, inputPath, outputPath});
     }
 
+    if (preamble) {
+        code = preamble + code;
+    }
+
     fsExtra.ensureFileSync(outputPath);
     fs.writeFileSync(outputPath, code, {encoding:'utf-8'});
 };