diff --git a/libc/arch-x86/string/sse2-strlen-atom.S b/libc/arch-x86/string/sse2-strlen-atom.S
index 8911868..81768fb 100644
--- a/libc/arch-x86/string/sse2-strlen-atom.S
+++ b/libc/arch-x86/string/sse2-strlen-atom.S
@@ -1,71 +1,112 @@
-#define STRLEN sse2_strlen_atom
+/*
+Copyright (c) 2011, Intel Corporation
+All rights reserved.
 
-#ifndef L
-# define L(label)	.L##label
-#endif
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
 
-#ifndef cfi_startproc
-# define cfi_startproc			.cfi_startproc
-#endif
+    * Redistributions of source code must retain the above copyright notice,
+    * this list of conditions and the following disclaimer.
 
-#ifndef cfi_endproc
-# define cfi_endproc			.cfi_endproc
-#endif
+    * 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.
 
-#ifndef cfi_rel_offset
-# define cfi_rel_offset(reg, off)	.cfi_rel_offset reg, off
-#endif
+    * 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.
 
-#ifndef cfi_restore
-# define cfi_restore(reg)		.cfi_restore reg
-#endif
+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 cfi_adjust_cfa_offset
-# define cfi_adjust_cfa_offset(off)	.cfi_adjust_cfa_offset off
-#endif
+#ifndef USE_AS_STRCAT
 
-#ifndef cfi_remember_state
-# define cfi_remember_state		.cfi_remember_state
-#endif
+# ifndef STRLEN
+#  define STRLEN strlen
+# endif
 
-#ifndef cfi_restore_state
-# define cfi_restore_state		.cfi_restore_state
-#endif
+# ifndef L
+#  define L(label)	.L##label
+# endif
 
-#ifndef ENTRY
-# define ENTRY(name)			\
-	.type name,  @function; 	\
-	.globl name;			\
-	.p2align 4;			\
-name:					\
+# ifndef cfi_startproc
+#  define cfi_startproc	.cfi_startproc
+# endif
+
+# ifndef cfi_endproc
+#  define cfi_endproc	.cfi_endproc
+# endif
+
+/* calee safe register only for strnlen is required */
+
+# ifdef USE_AS_STRNLEN
+#  ifndef cfi_rel_offset
+#   define cfi_rel_offset(reg, off)	.cfi_rel_offset reg, off
+#  endif
+
+#  ifndef cfi_restore
+#   define cfi_restore(reg)	.cfi_restore reg
+#  endif
+
+#  ifndef cfi_adjust_cfa_offset
+#   define cfi_adjust_cfa_offset(off)	.cfi_adjust_cfa_offset off
+#  endif
+# endif
+
+# ifndef ENTRY
+#  define ENTRY(name)	\
+	.type name,  @function;	\
+	.globl name;	\
+	.p2align 4;	\
+name:	\
 	cfi_startproc
-#endif
+# endif
 
-#ifndef END
-# define END(name)			\
-	cfi_endproc;			\
+# ifndef END
+#  define END(name)	\
+	cfi_endproc;	\
 	.size name, .-name
-#endif
+# endif
 
-#define CFI_PUSH(REG)						\
-  cfi_adjust_cfa_offset (4);					\
-  cfi_rel_offset (REG, 0)
+# define PARMS	4
+# define STR	PARMS
+# define RETURN	ret
 
-#define CFI_POP(REG)						\
-  cfi_adjust_cfa_offset (-4);					\
-  cfi_restore (REG)
+# ifdef USE_AS_STRNLEN
+#  define LEN	PARMS + 8
+#  define CFI_PUSH(REG)	\
+	cfi_adjust_cfa_offset (4);	\
+	cfi_rel_offset (REG, 0)
 
-#define PUSH(REG)	pushl REG; CFI_PUSH (REG)
-#define POP(REG)	popl REG; CFI_POP (REG)
-#define PARMS		4
-#define	STR		PARMS
-#define ENTRANCE
-#define RETURN		ret
+#  define CFI_POP(REG)	\
+	cfi_adjust_cfa_offset (-4);	\
+	cfi_restore (REG)
+
+#  define PUSH(REG)	pushl	REG;	CFI_PUSH (REG)
+#  define POP(REG)	popl	REG;	CFI_POP (REG)
+#  undef RETURN
+#  define RETURN	POP (%edi); ret; CFI_PUSH(%edi);
+# endif
 
 	.text
 ENTRY (STRLEN)
-	ENTRANCE
 	mov	STR(%esp), %edx
+# ifdef USE_AS_STRNLEN
+	PUSH	(%edi)
+	movl	LEN(%esp), %edi
+	sub	$4, %edi
+	jbe	L(len_less4_prolog)
+# endif
+#endif
 	xor	%eax, %eax
 	cmpb	$0, (%edx)
 	jz	L(exit_tail0)
@@ -75,6 +116,12 @@
 	jz	L(exit_tail2)
 	cmpb	$0, 3(%edx)
 	jz	L(exit_tail3)
+
+#ifdef USE_AS_STRNLEN
+	sub	$4, %edi
+	jbe	L(len_less8_prolog)
+#endif
+
 	cmpb	$0, 4(%edx)
 	jz	L(exit_tail4)
 	cmpb	$0, 5(%edx)
@@ -83,6 +130,12 @@
 	jz	L(exit_tail6)
 	cmpb	$0, 7(%edx)
 	jz	L(exit_tail7)
+
+#ifdef USE_AS_STRNLEN
+	sub	$4, %edi
+	jbe	L(len_less12_prolog)
+#endif
+
 	cmpb	$0, 8(%edx)
 	jz	L(exit_tail8)
 	cmpb	$0, 9(%edx)
@@ -91,6 +144,12 @@
 	jz	L(exit_tail10)
 	cmpb	$0, 11(%edx)
 	jz	L(exit_tail11)
+
+#ifdef USE_AS_STRNLEN
+	sub	$4, %edi
+	jbe	L(len_less16_prolog)
+#endif
+
 	cmpb	$0, 12(%edx)
 	jz	L(exit_tail12)
 	cmpb	$0, 13(%edx)
@@ -99,211 +158,531 @@
 	jz	L(exit_tail14)
 	cmpb	$0, 15(%edx)
 	jz	L(exit_tail15)
+
 	pxor	%xmm0, %xmm0
-	mov	%edx, %eax
-	mov	%edx, %ecx
+	lea	16(%edx), %eax
+	mov	%eax, %ecx
 	and	$-16, %eax
-	add	$16, %ecx
-	add	$16, %eax
+
+#ifdef USE_AS_STRNLEN
+	and	$15, %edx
+	add	%edx, %edi
+	sub	$64, %edi
+	jbe	L(len_less64)
+#endif
 
 	pcmpeqb	(%eax), %xmm0
 	pmovmskb %xmm0, %edx
 	pxor	%xmm1, %xmm1
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
 	pcmpeqb	(%eax), %xmm1
 	pmovmskb %xmm1, %edx
 	pxor	%xmm2, %xmm2
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
-
 	pcmpeqb	(%eax), %xmm2
 	pmovmskb %xmm2, %edx
 	pxor	%xmm3, %xmm3
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
 	pcmpeqb	(%eax), %xmm3
 	pmovmskb %xmm3, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
+#ifdef USE_AS_STRNLEN
+	sub	$64, %edi
+	jbe	L(len_less64)
+#endif
+
 	pcmpeqb	(%eax), %xmm0
 	pmovmskb %xmm0, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
 	pcmpeqb	(%eax), %xmm1
 	pmovmskb %xmm1, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
 	pcmpeqb	(%eax), %xmm2
 	pmovmskb %xmm2, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
 	pcmpeqb	(%eax), %xmm3
 	pmovmskb %xmm3, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
+#ifdef USE_AS_STRNLEN
+	sub	$64, %edi
+	jbe	L(len_less64)
+#endif
+
 	pcmpeqb	(%eax), %xmm0
 	pmovmskb %xmm0, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
 	pcmpeqb	(%eax), %xmm1
 	pmovmskb %xmm1, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
 	pcmpeqb	(%eax), %xmm2
 	pmovmskb %xmm2, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
 	pcmpeqb	(%eax), %xmm3
 	pmovmskb %xmm3, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
+#ifdef USE_AS_STRNLEN
+	sub	$64, %edi
+	jbe	L(len_less64)
+#endif
+
 	pcmpeqb	(%eax), %xmm0
 	pmovmskb %xmm0, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
 	pcmpeqb	(%eax), %xmm1
 	pmovmskb %xmm1, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
 	pcmpeqb	(%eax), %xmm2
 	pmovmskb %xmm2, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
 	pcmpeqb	(%eax), %xmm3
 	pmovmskb %xmm3, %edx
-	test	%edx, %edx
 	lea	16(%eax), %eax
+	test	%edx, %edx
 	jnz	L(exit)
 
+#ifdef USE_AS_STRNLEN
+	mov	%eax, %edx
+	and	$63, %edx
+	add	%edx, %edi
+#endif
+
 	and	$-0x40, %eax
-	PUSH (%esi)
-	PUSH (%edi)
-	PUSH (%ebx)
-	PUSH (%ebp)
-	xor	%ebp, %ebp
-L(aligned_64):
-	pcmpeqb	(%eax), %xmm0
-	pcmpeqb	16(%eax), %xmm1
-	pcmpeqb	32(%eax), %xmm2
-	pcmpeqb	48(%eax), %xmm3
-	pmovmskb %xmm0, %edx
-	pmovmskb %xmm1, %esi
-	pmovmskb %xmm2, %edi
-	pmovmskb %xmm3, %ebx
-	or	%edx, %ebp
-	or	%esi, %ebp
-	or	%edi, %ebp
-	or	%ebx, %ebp
+
+	.p2align 4
+L(aligned_64_loop):
+#ifdef USE_AS_STRNLEN
+	sub	$64, %edi
+	jbe	L(len_less64)
+#endif
+	movaps	(%eax), %xmm0
+	movaps	16(%eax), %xmm1
+	movaps	32(%eax), %xmm2
+	movaps	48(%eax), %xmm6
+	pminub	%xmm1, %xmm0
+	pminub	%xmm6, %xmm2
+	pminub	%xmm0, %xmm2
+	pcmpeqb	%xmm3, %xmm2
+	pmovmskb %xmm2, %edx
 	lea	64(%eax), %eax
-	jz	L(aligned_64)
-L(48leave):
 	test	%edx, %edx
-	jnz	L(aligned_64_exit_16)
-	test	%esi, %esi
-	jnz	L(aligned_64_exit_32)
-	test	%edi, %edi
-	jnz	L(aligned_64_exit_48)
-	mov	%ebx, %edx
-	lea	(%eax), %eax
-	jmp	L(aligned_64_exit)
-L(aligned_64_exit_48):
-	lea	-16(%eax), %eax
-	mov	%edi, %edx
-	jmp	L(aligned_64_exit)
-L(aligned_64_exit_32):
-	lea	-32(%eax), %eax
-	mov	%esi, %edx
-	jmp	L(aligned_64_exit)
-L(aligned_64_exit_16):
-	lea	-48(%eax), %eax
-L(aligned_64_exit):
-	POP (%ebp)
-	POP (%ebx)
-	POP (%edi)
-	POP (%esi)
+	jz	L(aligned_64_loop)
+
+	pcmpeqb	-64(%eax), %xmm3
+	pmovmskb %xmm3, %edx
+	lea	48(%ecx), %ecx
+	test	%edx, %edx
+	jnz	L(exit)
+
+	pcmpeqb	%xmm1, %xmm3
+	pmovmskb %xmm3, %edx
+	lea	-16(%ecx), %ecx
+	test	%edx, %edx
+	jnz	L(exit)
+
+	pcmpeqb	-32(%eax), %xmm3
+	pmovmskb %xmm3, %edx
+	lea	-16(%ecx), %ecx
+	test	%edx, %edx
+	jnz	L(exit)
+
+	pcmpeqb	%xmm6, %xmm3
+	pmovmskb %xmm3, %edx
+	lea	-16(%ecx), %ecx
 L(exit):
 	sub	%ecx, %eax
 	test	%dl, %dl
 	jz	L(exit_high)
+
+	mov	%dl, %cl
+	and	$15, %cl
+	jz	L(exit_8)
 	test	$0x01, %dl
 	jnz	L(exit_tail0)
-
 	test	$0x02, %dl
 	jnz	L(exit_tail1)
-
 	test	$0x04, %dl
 	jnz	L(exit_tail2)
+	add	$3, %eax
+	RETURN
 
-	test	$0x08, %dl
-	jnz	L(exit_tail3)
-
+	.p2align 4
+L(exit_8):
 	test	$0x10, %dl
 	jnz	L(exit_tail4)
-
 	test	$0x20, %dl
 	jnz	L(exit_tail5)
-
 	test	$0x40, %dl
 	jnz	L(exit_tail6)
 	add	$7, %eax
+	RETURN
+
+	.p2align 4
+L(exit_high):
+	mov	%dh, %ch
+	and	$15, %ch
+	jz	L(exit_high_8)
+	test	$0x01, %dh
+	jnz	L(exit_tail8)
+	test	$0x02, %dh
+	jnz	L(exit_tail9)
+	test	$0x04, %dh
+	jnz	L(exit_tail10)
+	add	$11, %eax
+	RETURN
+
+	.p2align 4
+L(exit_high_8):
+	test	$0x10, %dh
+	jnz	L(exit_tail12)
+	test	$0x20, %dh
+	jnz	L(exit_tail13)
+	test	$0x40, %dh
+	jnz	L(exit_tail14)
+	add	$15, %eax
 L(exit_tail0):
 	RETURN
 
-L(exit_high):
-	add	$8, %eax
-	test	$0x01, %dh
-	jnz	L(exit_tail0)
+#ifdef USE_AS_STRNLEN
 
-	test	$0x02, %dh
-	jnz	L(exit_tail1)
+	.p2align 4
+L(len_less64):
+	pxor	%xmm0, %xmm0
+	add	$64, %edi
 
-	test	$0x04, %dh
-	jnz	L(exit_tail2)
+	pcmpeqb	(%eax), %xmm0
+	pmovmskb %xmm0, %edx
+	pxor	%xmm1, %xmm1
+	lea	16(%eax), %eax
+	test	%edx, %edx
+	jnz	L(strnlen_exit)
 
-	test	$0x08, %dh
-	jnz	L(exit_tail3)
+	sub	$16, %edi
+	jbe	L(return_start_len)
 
-	test	$0x10, %dh
-	jnz	L(exit_tail4)
+	pcmpeqb	(%eax), %xmm1
+	pmovmskb %xmm1, %edx
+	lea	16(%eax), %eax
+	test	%edx, %edx
+	jnz	L(strnlen_exit)
 
-	test	$0x20, %dh
-	jnz	L(exit_tail5)
+	sub	$16, %edi
+	jbe	L(return_start_len)
 
-	test	$0x40, %dh
-	jnz	L(exit_tail6)
-	add	$7, %eax
+	pcmpeqb	(%eax), %xmm0
+	pmovmskb %xmm0, %edx
+	lea	16(%eax), %eax
+	test	%edx, %edx
+	jnz	L(strnlen_exit)
+
+	sub	$16, %edi
+	jbe	L(return_start_len)
+
+	pcmpeqb	(%eax), %xmm1
+	pmovmskb %xmm1, %edx
+	lea	16(%eax), %eax
+	test	%edx, %edx
+	jnz	L(strnlen_exit)
+
+#ifndef USE_AS_STRLCAT
+	movl	LEN(%esp), %eax
 	RETURN
+#else
+	jmp	L(return_start_len)
+#endif
+
+	.p2align 4
+L(strnlen_exit):
+	sub	%ecx, %eax
+
+	test	%dl, %dl
+	jz	L(strnlen_exit_high)
+	mov	%dl, %cl
+	and	$15, %cl
+	jz	L(strnlen_exit_8)
+	test	$0x01, %dl
+	jnz	L(exit_tail0)
+	test	$0x02, %dl
+	jnz	L(strnlen_exit_tail1)
+	test	$0x04, %dl
+	jnz	L(strnlen_exit_tail2)
+	sub	$4, %edi
+	jb	L(return_start_len)
+	lea	3(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_8):
+	test	$0x10, %dl
+	jnz	L(strnlen_exit_tail4)
+	test	$0x20, %dl
+	jnz	L(strnlen_exit_tail5)
+	test	$0x40, %dl
+	jnz	L(strnlen_exit_tail6)
+	sub	$8, %edi
+	jb	L(return_start_len)
+	lea	7(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_high):
+	mov	%dh, %ch
+	and	$15, %ch
+	jz	L(strnlen_exit_high_8)
+	test	$0x01, %dh
+	jnz	L(strnlen_exit_tail8)
+	test	$0x02, %dh
+	jnz	L(strnlen_exit_tail9)
+	test	$0x04, %dh
+	jnz	L(strnlen_exit_tail10)
+	sub	$12, %edi
+	jb	L(return_start_len)
+	lea	11(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_high_8):
+	test	$0x10, %dh
+	jnz	L(strnlen_exit_tail12)
+	test	$0x20, %dh
+	jnz	L(strnlen_exit_tail13)
+	test	$0x40, %dh
+	jnz	L(strnlen_exit_tail14)
+	sub	$16, %edi
+	jb	L(return_start_len)
+	lea	15(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_tail1):
+	sub	$2, %edi
+	jb	L(return_start_len)
+	lea	1(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_tail2):
+	sub	$3, %edi
+	jb	L(return_start_len)
+	lea	2(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_tail4):
+	sub	$5, %edi
+	jb	L(return_start_len)
+	lea	4(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_tail5):
+	sub	$6, %edi
+	jb	L(return_start_len)
+	lea	5(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_tail6):
+	sub	$7, %edi
+	jb	L(return_start_len)
+	lea	6(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_tail8):
+	sub	$9, %edi
+	jb	L(return_start_len)
+	lea	8(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_tail9):
+	sub	$10, %edi
+	jb	L(return_start_len)
+	lea	9(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_tail10):
+	sub	$11, %edi
+	jb	L(return_start_len)
+	lea	10(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_tail12):
+	sub	$13, %edi
+	jb	L(return_start_len)
+	lea	12(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_tail13):
+	sub	$14, %edi
+	jb	L(return_start_len)
+	lea	13(%eax), %eax
+	RETURN
+
+	.p2align 4
+L(strnlen_exit_tail14):
+	sub	$15, %edi
+	jb	L(return_start_len)
+	lea	14(%eax), %eax
+	RETURN
+
+#ifndef USE_AS_STRLCAT
+	.p2align 4
+L(return_start_len):
+	movl	LEN(%esp), %eax
+	RETURN
+#endif
+
+/* for prolog only */
+
+	.p2align 4
+L(len_less4_prolog):
+	xor	%eax, %eax
+
+	add	$4, %edi
+	jz	L(exit_tail0)
+
+	cmpb	$0, (%edx)
+	jz	L(exit_tail0)
+	cmp	$1, %edi
+	je	L(exit_tail1)
+
+	cmpb	$0, 1(%edx)
+	jz	L(exit_tail1)
+	cmp	$2, %edi
+	je	L(exit_tail2)
+
+	cmpb	$0, 2(%edx)
+	jz	L(exit_tail2)
+	cmp	$3, %edi
+	je	L(exit_tail3)
+
+	cmpb	$0, 3(%edx)
+	jz	L(exit_tail3)
+	mov	%edi, %eax
+	RETURN
+
+	.p2align 4
+L(len_less8_prolog):
+	add	$4, %edi
+
+	cmpb	$0, 4(%edx)
+	jz	L(exit_tail4)
+	cmp	$1, %edi
+	je	L(exit_tail5)
+
+	cmpb	$0, 5(%edx)
+	jz	L(exit_tail5)
+	cmp	$2, %edi
+	je	L(exit_tail6)
+
+	cmpb	$0, 6(%edx)
+	jz	L(exit_tail6)
+	cmp	$3, %edi
+	je	L(exit_tail7)
+
+	cmpb	$0, 7(%edx)
+	jz	L(exit_tail7)
+	mov	$8, %eax
+	RETURN
+
+
+	.p2align 4
+L(len_less12_prolog):
+	add	$4, %edi
+
+	cmpb	$0, 8(%edx)
+	jz	L(exit_tail8)
+	cmp	$1, %edi
+	je	L(exit_tail9)
+
+	cmpb	$0, 9(%edx)
+	jz	L(exit_tail9)
+	cmp	$2, %edi
+	je	L(exit_tail10)
+
+	cmpb	$0, 10(%edx)
+	jz	L(exit_tail10)
+	cmp	$3, %edi
+	je	L(exit_tail11)
+
+	cmpb	$0, 11(%edx)
+	jz	L(exit_tail11)
+	mov	$12, %eax
+	RETURN
+
+	.p2align 4
+L(len_less16_prolog):
+	add	$4, %edi
+
+	cmpb	$0, 12(%edx)
+	jz	L(exit_tail12)
+	cmp	$1, %edi
+	je	L(exit_tail13)
+
+	cmpb	$0, 13(%edx)
+	jz	L(exit_tail13)
+	cmp	$2, %edi
+	je	L(exit_tail14)
+
+	cmpb	$0, 14(%edx)
+	jz	L(exit_tail14)
+	cmp	$3, %edi
+	je	L(exit_tail15)
+
+	cmpb	$0, 15(%edx)
+	jz	L(exit_tail15)
+	mov	$16, %eax
+	RETURN
+#endif
 
 	.p2align 4
 L(exit_tail1):
@@ -364,6 +743,7 @@
 
 L(exit_tail15):
 	add	$15, %eax
-	ret
-
+#ifndef USE_AS_STRCAT
+	RETURN
 END (STRLEN)
+#endif