diff --git a/lib/negvti2.c b/lib/negvti2.c
new file mode 100644
index 0000000..ced05e8
--- /dev/null
+++ b/lib/negvti2.c
@@ -0,0 +1,32 @@
+//===-- negvti2.c - Implement __negvti2 -----------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __negvti2 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#if __x86_64
+
+#include "int_lib.h"
+#include <stdlib.h>
+
+// Returns: -a
+
+// Effects: aborts if -a overflows
+
+ti_int
+__negvti2(ti_int a)
+{
+    const ti_int MIN = (ti_int)1 << ((int)(sizeof(ti_int) * CHAR_BIT)-1);
+    if (a == MIN)
+        abort();
+    return -a;
+}
+
+#endif