diff --git a/src/libc/secure/memccpy_chk.c b/src/libc/secure/memccpy_chk.c
new file mode 100644
index 000000000..5f472c098
--- /dev/null
+++ b/src/libc/secure/memccpy_chk.c
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2012-2013 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include "secure.h"
+
+void *
+__memccpy_chk (void *dest, const void *src, int c, size_t len, size_t dstlen)
+{
+  void *retval;
+
+  if (__builtin_expect (dstlen < len, 0))
+    __chk_fail_overflow ();
+
+  /* retval is NULL if len was copied, otherwise retval is the
+   * byte *after* the last one written.
+   */
+  retval = memccpy (dest, src, c, len);
+
+  if (retval != NULL) {
+    len = (uintptr_t)retval - (uintptr_t)dest;
+  }
+
+  __chk_overlap(dest, len, src, len);
+
+  return retval;
+}
diff --git a/src/libc/secure/secure.c b/src/libc/secure/secure.c
new file mode 100644
index 000000000..a88f524e0
--- /dev/null
+++ b/src/libc/secure/secure.c
@@ -0,0 +1,30 @@
+#include "secure.h"
+#include <syslog.h>
+#include <sys/sysctl.h>
+#include <sys/param.h>
+#include <unistd.h>
+#include <stdint.h>
+
+extern void __abort(void) __dead2;
+extern void __chk_fail (void) __attribute__((__noreturn__));
+
+void __chk_fail_overflow (void) __attribute__((__noreturn__))
+{
+	__chk_fail();
+}
+
+void __chk_fail_overlap (void) __attribute__((__noreturn__))
+{
+  const char message[] = "[%d] detected illegal buffer overlap";
+
+  syslog(LOG_CRIT, message, getpid());
+
+  __abort();
+}
+
+void __chk_overlap (const void *a, size_t an, const void *b, size_t bn)
+{
+	if (((uintptr_t)a) <= ((uintptr_t)b)+bn && ((uintptr_t)b) <= ((uintptr_t)a)+an)
+		__chk_fail_overlap();
+}
+
diff --git a/src/libc/secure/secure.h b/src/libc/secure/secure.h
new file mode 100644
index 000000000..07bafc614
--- /dev/null
+++ b/src/libc/secure/secure.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2013 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#ifndef _SECURE_H_
+
+#include <sys/types.h>
+
+extern void __chk_fail_overflow (void) __attribute__((__noreturn__));
+extern void __chk_fail_overlap (void) __attribute__((__noreturn__));
+
+/* Assert if a -> a+an and b -> b+bn overlap.
+ * 0-lengths don't overlap anything.
+ */
+extern void __chk_overlap (const void *a, size_t an, const void *b, size_t bn);
+
+/* Do we avoid the overlap check for older APIs? */
+extern int __chk_assert_no_overlap;
+
+#endif
diff --git a/src/libc/secure/strlcat_chk.c b/src/libc/secure/strlcat_chk.c
new file mode 100644
index 000000000..5eb434ee9
--- /dev/null
+++ b/src/libc/secure/strlcat_chk.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2012-2013 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include "secure.h"
+
+size_t
+__strlcat_chk (char *restrict dest, char *restrict src,
+	       size_t len, size_t dstlen)
+{
+  size_t initial_srclen;
+  size_t initial_dstlen;
+
+  if (__builtin_expect (dstlen < len, 0))
+    __chk_fail_overflow ();
+
+  initial_srclen = strlen(src);
+  initial_dstlen = strnlen(dest, len);
+
+  if (initial_dstlen == len)
+    return len+initial_srclen;
+
+  if (initial_srclen < len - initial_dstlen) {
+    __chk_overlap(dest, initial_srclen + initial_dstlen + 1, src, initial_srclen + 1);
+    memcpy(dest+initial_dstlen, src, initial_srclen + 1);
+  } else {
+    __chk_overlap(dest, initial_srclen + initial_dstlen + 1, src, len - initial_dstlen - 1);
+    memcpy(dest+initial_dstlen, src, len - initial_dstlen - 1);
+    dest[len-1] = '\0';
+  }
+
+  return initial_srclen + initial_dstlen;
+}
diff --git a/src/libc/secure/strlcpy_chk.c b/src/libc/secure/strlcpy_chk.c
new file mode 100644
index 000000000..504e7662c
--- /dev/null
+++ b/src/libc/secure/strlcpy_chk.c
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2012-2013 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include "secure.h"
+
+size_t
+__strlcpy_chk (char *restrict dest, char *restrict src,
+	       size_t len, size_t dstlen)
+{
+  size_t retval;
+  if (__builtin_expect (dstlen < len, 0))
+    __chk_fail_overflow ();
+
+  retval = strlcpy (dest, src, len);
+
+  if (retval < len)
+    len = retval + 1;
+
+  __chk_overlap(dest, len, src, len);
+
+  return retval;
+}