diff --git a/test/mjsunit/string-natives.js b/test/mjsunit/string-natives.js
new file mode 100644
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+++ b/test/mjsunit/string-natives.js
@@ -0,0 +1,79 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --expose-gc --allow-natives-syntax
+
+function test() {
+  var s1 = %NewString(26, true);
+  for (i = 0; i < 26; i++) %_OneByteSeqStringSetChar(i, 65, s1);
+  assertEquals("AAAAAAAAAAAAAAAAAAAAAAAAAA", s1);
+  %_OneByteSeqStringSetChar(25, 66, s1);
+  assertEquals("AAAAAAAAAAAAAAAAAAAAAAAAAB", s1);
+  for (i = 0; i < 26; i++) %_OneByteSeqStringSetChar(i, i+65, s1);
+  assertEquals("ABCDEFGHIJKLMNOPQRSTUVWXYZ", s1);
+  s1 = %TruncateString(s1, 13);
+  assertEquals("ABCDEFGHIJKLM", s1);
+
+  var s2 = %NewString(26, false);
+  for (i = 0; i < 26; i++) %_TwoByteSeqStringSetChar(i, 65, s2);
+  assertEquals("AAAAAAAAAAAAAAAAAAAAAAAAAA", s2);
+  %_TwoByteSeqStringSetChar(25, 66, s2);
+  assertEquals("AAAAAAAAAAAAAAAAAAAAAAAAAB", s2);
+  for (i = 0; i < 26; i++) %_TwoByteSeqStringSetChar(i, i+65, s2);
+  assertEquals("ABCDEFGHIJKLMNOPQRSTUVWXYZ", s2);
+  s2 = %TruncateString(s2, 13);
+  assertEquals("ABCDEFGHIJKLM", s2);
+
+  var s3 = %NewString(26, false);
+  for (i = 0; i < 26; i++) %_TwoByteSeqStringSetChar(i, i+1000, s3);
+  for (i = 0; i < 26; i++) assertEquals(s3[i], String.fromCharCode(i+1000));
+
+  var a = [];
+  for (var i = 0; i < 1000; i++) {
+    var s = %NewString(10000, i % 2 == 1);
+    a.push(s);
+  }
+
+  gc();
+
+  for (var i = 0; i < 1000; i++) {
+    assertEquals(10000, a[i].length);
+    a[i] = %TruncateString(a[i], 5000);
+  }
+
+  gc();
+
+  for (var i = 0; i < 1000; i++) {
+    assertEquals(5000, a[i].length);
+  }
+}
+
+
+test();
+test();
+%OptimizeFunctionOnNextCall(test);
+test();