diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/testOverwrittenArgumentsWithUndefined.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/testOverwrittenArgumentsWithUndefined.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,24 @@
+function f() {
+    var a = arguments;
+    eval("assertEq(arguments[0], 42)");
+    eval("assertEq(arguments, a)");
+    arguments = undefined;
+    eval("assertEq(arguments, undefined)");
+    arguments = a;
+    eval("assertEq(arguments[0], 42)");
+    eval("assertEq(arguments, a)");
+}
+f(42);
+
+function f(z) {
+    var a = arguments;
+    eval("assertEq(arguments[0], 42)");
+    eval("assertEq(arguments, a)");
+    arguments = undefined;
+    eval("assertEq(arguments, undefined)");
+    z = 17;
+    eval("assertEq(a[0], 17)");
+    a[0] = 'ponies';
+    eval("assertEq(z, 'ponies')");
+}
+f(42);