diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_5/GC/regress-338653.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_5/GC/regress-338653.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,41 @@
+// |reftest| skip -- slow, killed on x86_64
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 338653;
+var summary = 'Force GC when JSRuntime.gcMallocBytes hits ' +
+  'JSRuntime.gcMaxMallocBytes';
+var actual = 'No Crash';
+var expect = 'No Crash';
+
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+print('This test should never fail explicitly. ' +
+      'You must view the memory usage during the test. ' +
+      'This test fails if the memory usage repeatedly spikes ' +
+      'by several hundred megabytes.');
+
+function dosubst()
+{
+  var f = '0x';
+  var s = f;
+
+  for (var i = 0; i < 18; i++)
+  {
+    s += s;
+  }
+
+  var index = s.indexOf(f);
+  while (index != -1 && index < 10000) {
+    s = s.substr(0, index) + '1' + s.substr(index + f.length);
+    index = s.indexOf(f);
+  }
+
+}
+
+dosubst(); 
+
+reportCompare(expect, actual, summary);