diff --git a/mozilla/js/tests/js1_8_1/regress/regress-495907.js b/mozilla/js/tests/js1_8_1/regress/regress-495907.js
new file mode 100644
index 00000000000..7d1a3a7b820
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+++ b/mozilla/js/tests/js1_8_1/regress/regress-495907.js
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is JavaScript Engine testing utilities.
+ *
+ * The Initial Developer of the Original Code is
+ * Mozilla Foundation.
+ * Portions created by the Initial Developer are Copyright (C) 2007
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s): Dave Mandelin
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+var gTestfile = 'regress-495907.js';
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 495907;
+var summary = 'Read upvar from trace-entry frame when created with top-level let';
+var actual = ''
+var expect = '00112233';
+//-----------------------------------------------------------------------------
+
+// The test code needs to run at top level in order to expose the bug.
+start_test();
+
+var o = [];
+for (let a = 0; a < 4; ++a) {
+    (function () {for (var b = 0; b < 2; ++b) {o.push(a);}}());
+}
+actual = o.join("");
+
+finish_test();
+//-----------------------------------------------------------------------------
+
+function start_test() {
+  enterFunc ('test');
+  printBugNumber(BUGNUMBER);
+  printStatus (summary);
+  jit(true);
+}
+
+function finish_test() {
+  jit(false);
+  reportCompare(expect, actual, summary);
+  exitFunc ('test');
+}