diff --git a/libc/Android.mk b/libc/Android.mk
index 95ff1ec..0133a05 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -205,6 +205,12 @@
 	string/strtok.c \
 	string/strtotimeval.c \
 	string/strxfrm.c \
+	string/__memcpy_chk.c \
+	string/__memmove_chk.c \
+	string/__strcat_chk.c \
+	string/__strcpy_chk.c \
+	string/__strncat_chk.c \
+	string/__strncpy_chk.c \
 	wchar/wcpcpy.c \
 	wchar/wcpncpy.c \
 	wchar/wcscasecmp.c \
diff --git a/libc/include/string.h b/libc/include/string.h
index 6e6c8e6..12c9500 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -85,6 +85,47 @@
 extern int    strcoll(const char *, const char *) __purefunc;
 extern size_t strxfrm(char *, const char *, size_t);
 
+#if defined(_FORTIFY_SOURCE) && _FORTIFY_SOURCE > 0 && defined(__OPTIMIZE__) && __OPTIMIZE__ > 0
+
+#define __BIONIC_FORTIFY_INLINE \
+    extern inline \
+    __attribute__ ((always_inline)) \
+    __attribute__ ((gnu_inline)) \
+    __attribute__ ((artificial))
+
+__BIONIC_FORTIFY_INLINE
+void *memcpy (void *dest, const void *src, size_t len) {
+    return __builtin___memcpy_chk (dest, src, len, __builtin_object_size (dest, 0));
+}
+
+__BIONIC_FORTIFY_INLINE
+void *memmove (void *dest, const void *src, size_t len) {
+    return __builtin___memmove_chk (dest, src, len, __builtin_object_size (dest, 0));
+}
+
+__BIONIC_FORTIFY_INLINE
+char *strcpy(char *dest, const char *src) {
+    return __builtin___strcpy_chk (dest, src, __builtin_object_size (dest, 0));
+}
+
+__BIONIC_FORTIFY_INLINE
+char *strncpy(char *dest, const char *src, size_t n) {
+    return __builtin___strncpy_chk(dest, src, n, __builtin_object_size (dest, 0));
+}
+
+__BIONIC_FORTIFY_INLINE
+char *strcat(char *dest, const char *src) {
+    return __builtin___strcat_chk (dest, src, __builtin_object_size (dest, 0));
+}
+
+__BIONIC_FORTIFY_INLINE
+char *strncat(char *dest, const char *src, size_t n) {
+    return __builtin___strncat_chk(dest, src, n, __builtin_object_size (dest, 0));
+}
+
+#undef __BIONIC_FORTIFY_INLINE
+#endif
+
 __END_DECLS
 
 #endif /* _STRING_H_ */
diff --git a/libc/string/__memcpy_chk.c b/libc/string/__memcpy_chk.c
new file mode 100644
index 0000000..aed3ec2
--- /dev/null
+++ b/libc/string/__memcpy_chk.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <private/logd.h>
+
+/*
+ * Runtime implementation of __builtin____memcpy_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 memcpy check is called if _FORTIFY_SOURCE is defined and
+ * greater than 0.
+ */
+void *__memcpy_chk (void *dest, const void *src,
+              size_t len, size_t dest_len)
+{
+    if (len > dest_len) {
+        __libc_android_log_print(ANDROID_LOG_FATAL, "libc",
+            "*** memcpy buffer overflow detected ***\n");
+        abort();
+    }
+
+    return memcpy(dest, src, len);
+}
diff --git a/libc/string/__memmove_chk.c b/libc/string/__memmove_chk.c
new file mode 100644
index 0000000..5a6eb4d
--- /dev/null
+++ b/libc/string/__memmove_chk.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <private/logd.h>
+
+/*
+ * Runtime implementation of __builtin____memmove_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 memmove check is called if _FORTIFY_SOURCE is defined and
+ * greater than 0.
+ */
+void *__memmove_chk (void *dest, const void *src,
+              size_t len, size_t dest_len)
+{
+    if (len > dest_len) {
+        __libc_android_log_print(ANDROID_LOG_FATAL, "libc",
+            "*** memmove buffer overflow detected ***\n");
+        abort();
+    }
+
+    return memmove(dest, src, len);
+}
diff --git a/libc/string/__strcat_chk.c b/libc/string/__strcat_chk.c
new file mode 100644
index 0000000..3e02052
--- /dev/null
+++ b/libc/string/__strcat_chk.c
@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <private/logd.h>
+
+/*
+ * Runtime implementation of __builtin____strcat_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 strcat check is called if _FORTIFY_SOURCE is defined and
+ * greater than 0.
+ */
+char *__strcat_chk (char *dest, const char *src, size_t dest_buf_size)
+{
+    // TODO: optimize so we don't scan src/dest twice.
+    size_t src_len  = strlen(src);
+    size_t dest_len = strlen(dest);
+
+    if (src_len + dest_len + 1 > dest_buf_size) {
+        __libc_android_log_print(ANDROID_LOG_FATAL, "libc",
+            "*** strcat buffer overflow detected ***\n");
+        abort();
+    }
+
+    return strcat(dest, src);
+}
diff --git a/libc/string/__strcpy_chk.c b/libc/string/__strcpy_chk.c
new file mode 100644
index 0000000..85aa19d
--- /dev/null
+++ b/libc/string/__strcpy_chk.c
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <private/logd.h>
+
+/*
+ * Runtime implementation of __builtin____strcpy_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 strcpy check is called if _FORTIFY_SOURCE is defined and
+ * greater than 0.
+ */
+char *__strcpy_chk (char *dest, const char *src, size_t dest_len)
+{
+    // TODO: optimize so we don't scan src twice.
+    size_t src_len = strlen(src) + 1;
+    if (src_len > dest_len) {
+        __libc_android_log_print(ANDROID_LOG_FATAL, "libc",
+            "*** strcpy buffer overflow detected ***\n");
+        abort();
+    }
+
+    return strcpy(dest, src);
+}
diff --git a/libc/string/__strncat_chk.c b/libc/string/__strncat_chk.c
new file mode 100644
index 0000000..9b0b84a
--- /dev/null
+++ b/libc/string/__strncat_chk.c
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <private/logd.h>
+
+/*
+ * Runtime implementation of __builtin____strncat_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 strncat check is called if _FORTIFY_SOURCE is defined and
+ * greater than 0.
+ */
+char *__strncat_chk (char *dest, const char *src,
+              size_t len, size_t dest_buf_size)
+{
+    // TODO: optimize so we don't scan src/dest twice.
+    size_t dest_len = strlen(dest);
+    size_t src_len = strlen(src);
+    if (src_len > len) {
+        src_len = len;
+    }
+
+    if (dest_len + src_len + 1 > dest_buf_size) {
+        __libc_android_log_print(ANDROID_LOG_FATAL, "libc",
+            "*** strncat buffer overflow detected ***\n");
+        abort();
+    }
+
+    return strncat(dest, src, len);
+}
diff --git a/libc/string/__strncpy_chk.c b/libc/string/__strncpy_chk.c
new file mode 100644
index 0000000..b87ef4b
--- /dev/null
+++ b/libc/string/__strncpy_chk.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <private/logd.h>
+
+/*
+ * Runtime implementation of __builtin____strncpy_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 strncpy check is called if _FORTIFY_SOURCE is defined and
+ * greater than 0.
+ */
+char *__strncpy_chk (char *dest, const char *src,
+              size_t len, size_t dest_len)
+{
+    if (len > dest_len) {
+        __libc_android_log_print(ANDROID_LOG_FATAL, "libc",
+            "*** strncpy buffer overflow detected ***\n");
+        abort();
+    }
+
+    return strncpy(dest, src, len);
+}