diff --git a/libc/arch-x86_64/string/sse2-strcat-slm.S b/libc/arch-x86_64/string/sse2-strcat-slm.S
new file mode 100644
index 0000000..dd8207f
--- /dev/null
+++ b/libc/arch-x86_64/string/sse2-strcat-slm.S
@@ -0,0 +1,87 @@
+/*
+Copyright (c) 2014, Intel Corporation
+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 Intel Corporation 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.
+*/
+
+#ifndef STRCAT
+# define STRCAT		strcat
+#endif
+
+#ifndef L
+# define L(label)		.L##label
+#endif
+
+#ifndef cfi_startproc
+# define cfi_startproc		 .cfi_startproc
+#endif
+
+#ifndef cfi_endproc
+# define cfi_endproc		.cfi_endproc
+#endif
+
+#ifndef ENTRY
+# define ENTRY(name)		\
+	.type name,  @function;		\
+	.globl name;		\
+	.p2align 4;		\
+name:		\
+	cfi_startproc
+#endif
+
+#ifndef END
+# define END(name)		\
+	cfi_endproc;		\
+	.size name, .-name
+#endif
+
+#define USE_AS_STRCAT
+
+.text
+ENTRY (STRCAT)
+	mov	%rdi, %r9
+#ifdef USE_AS_STRNCAT
+	mov	%rdx, %r8
+#endif
+
+#define RETURN jmp L(Strcpy)
+#include "sse2-strlen-slm.S"
+
+#undef RETURN
+#define RETURN ret
+
+L(Strcpy):
+	lea	(%r9, %rax), %rdi
+	mov	%rsi, %rcx
+	mov	%r9, %rax	/* save result */
+
+#ifdef USE_AS_STRNCAT
+	test	%r8, %r8
+	jz	L(ExitZero)
+# define USE_AS_STRNCPY
+#endif
+#include "sse2-strcpy-slm.S"