diff --git a/libc/bionic/__stpncpy_chk.cpp b/libc/bionic/__stpncpy_chk.cpp
new file mode 100644
index 0000000..6c9215c
--- /dev/null
+++ b/libc/bionic/__stpncpy_chk.cpp
@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ * 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.
+ *
+ * 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.
+ */
+
+#undef _FORTIFY_SOURCE
+
+#include <string.h>
+#include <stdlib.h>
+#include "private/libc_logging.h"
+
+/*
+ * Runtime implementation of __builtin____stpncpy_chk.
+ *
+ * See
+ *   http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html
+ *   http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
+ * for details.
+ *
+ * This stpncpy check is called if _FORTIFY_SOURCE is defined and
+ * greater than 0.
+ */
+extern "C" char* __stpncpy_chk(char* __restrict dest, const char* __restrict src,
+                               size_t len, size_t dest_len) {
+  if (__predict_false(len > dest_len)) {
+    __fortify_chk_fail("stpncpy: prevented write past end of buffer",
+                       BIONIC_EVENT_STPNCPY_BUFFER_OVERFLOW);
+  }
+
+  return stpncpy(dest, src, len);
+}
+
+/*
+ * __stpncpy_chk2
+ *
+ * This is a variant of __stpncpy_chk, but it also checks to make
+ * sure we don't read beyond the end of "src". The code for this is
+ * based on the original version of stpncpy, but modified to check
+ * how much we read from "src" at the end of the copy operation.
+ */
+extern "C" char* __stpncpy_chk2(char* __restrict dst, const char* __restrict src,
+              size_t n, size_t dest_len, size_t src_len)
+{
+  if (__predict_false(n > dest_len)) {
+    __fortify_chk_fail("stpncpy: prevented write past end of buffer",
+                       BIONIC_EVENT_STPNCPY_BUFFER_OVERFLOW);
+  }
+  if (n != 0) {
+    char* d = dst;
+    const char* s = src;
+
+    do {
+      if ((*d++ = *s++) == 0) {
+        /* NUL pad the remaining n-1 bytes */
+        while (--n != 0) {
+          *d++ = 0;
+        }
+        break;
+      }
+    } while (--n != 0);
+
+    size_t s_copy_len = static_cast<size_t>(s - src);
+    if (__predict_false(s_copy_len > src_len)) {
+      __fortify_chk_fail("stpncpy: prevented read past end of buffer", 0);
+    }
+  }
+
+  return dst;
+}