diff --git a/libc/arch-x86/string/sse2-strlen-atom.S b/libc/arch-x86/string/sse2-strlen-atom.S
new file mode 100644
index 0000000..8911868
--- /dev/null
+++ b/libc/arch-x86/string/sse2-strlen-atom.S
@@ -0,0 +1,369 @@
+#define STRLEN sse2_strlen_atom
+
+#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 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
+
+#ifndef cfi_remember_state
+# define cfi_remember_state		.cfi_remember_state
+#endif
+
+#ifndef cfi_restore_state
+# define cfi_restore_state		.cfi_restore_state
+#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 CFI_PUSH(REG)						\
+  cfi_adjust_cfa_offset (4);					\
+  cfi_rel_offset (REG, 0)
+
+#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)
+#define PARMS		4
+#define	STR		PARMS
+#define ENTRANCE
+#define RETURN		ret
+
+	.text
+ENTRY (STRLEN)
+	ENTRANCE
+	mov	STR(%esp), %edx
+	xor	%eax, %eax
+	cmpb	$0, (%edx)
+	jz	L(exit_tail0)
+	cmpb	$0, 1(%edx)
+	jz	L(exit_tail1)
+	cmpb	$0, 2(%edx)
+	jz	L(exit_tail2)
+	cmpb	$0, 3(%edx)
+	jz	L(exit_tail3)
+	cmpb	$0, 4(%edx)
+	jz	L(exit_tail4)
+	cmpb	$0, 5(%edx)
+	jz	L(exit_tail5)
+	cmpb	$0, 6(%edx)
+	jz	L(exit_tail6)
+	cmpb	$0, 7(%edx)
+	jz	L(exit_tail7)
+	cmpb	$0, 8(%edx)
+	jz	L(exit_tail8)
+	cmpb	$0, 9(%edx)
+	jz	L(exit_tail9)
+	cmpb	$0, 10(%edx)
+	jz	L(exit_tail10)
+	cmpb	$0, 11(%edx)
+	jz	L(exit_tail11)
+	cmpb	$0, 12(%edx)
+	jz	L(exit_tail12)
+	cmpb	$0, 13(%edx)
+	jz	L(exit_tail13)
+	cmpb	$0, 14(%edx)
+	jz	L(exit_tail14)
+	cmpb	$0, 15(%edx)
+	jz	L(exit_tail15)
+	pxor	%xmm0, %xmm0
+	mov	%edx, %eax
+	mov	%edx, %ecx
+	and	$-16, %eax
+	add	$16, %ecx
+	add	$16, %eax
+
+	pcmpeqb	(%eax), %xmm0
+	pmovmskb %xmm0, %edx
+	pxor	%xmm1, %xmm1
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm1
+	pmovmskb %xmm1, %edx
+	pxor	%xmm2, %xmm2
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+
+	pcmpeqb	(%eax), %xmm2
+	pmovmskb %xmm2, %edx
+	pxor	%xmm3, %xmm3
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm3
+	pmovmskb %xmm3, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm0
+	pmovmskb %xmm0, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm1
+	pmovmskb %xmm1, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm2
+	pmovmskb %xmm2, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm3
+	pmovmskb %xmm3, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm0
+	pmovmskb %xmm0, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm1
+	pmovmskb %xmm1, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm2
+	pmovmskb %xmm2, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm3
+	pmovmskb %xmm3, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm0
+	pmovmskb %xmm0, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm1
+	pmovmskb %xmm1, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm2
+	pmovmskb %xmm2, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	pcmpeqb	(%eax), %xmm3
+	pmovmskb %xmm3, %edx
+	test	%edx, %edx
+	lea	16(%eax), %eax
+	jnz	L(exit)
+
+	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
+	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)
+L(exit):
+	sub	%ecx, %eax
+	test	%dl, %dl
+	jz	L(exit_high)
+	test	$0x01, %dl
+	jnz	L(exit_tail0)
+
+	test	$0x02, %dl
+	jnz	L(exit_tail1)
+
+	test	$0x04, %dl
+	jnz	L(exit_tail2)
+
+	test	$0x08, %dl
+	jnz	L(exit_tail3)
+
+	test	$0x10, %dl
+	jnz	L(exit_tail4)
+
+	test	$0x20, %dl
+	jnz	L(exit_tail5)
+
+	test	$0x40, %dl
+	jnz	L(exit_tail6)
+	add	$7, %eax
+L(exit_tail0):
+	RETURN
+
+L(exit_high):
+	add	$8, %eax
+	test	$0x01, %dh
+	jnz	L(exit_tail0)
+
+	test	$0x02, %dh
+	jnz	L(exit_tail1)
+
+	test	$0x04, %dh
+	jnz	L(exit_tail2)
+
+	test	$0x08, %dh
+	jnz	L(exit_tail3)
+
+	test	$0x10, %dh
+	jnz	L(exit_tail4)
+
+	test	$0x20, %dh
+	jnz	L(exit_tail5)
+
+	test	$0x40, %dh
+	jnz	L(exit_tail6)
+	add	$7, %eax
+	RETURN
+
+	.p2align 4
+L(exit_tail1):
+	add	$1, %eax
+	RETURN
+
+L(exit_tail2):
+	add	$2, %eax
+	RETURN
+
+L(exit_tail3):
+	add	$3, %eax
+	RETURN
+
+L(exit_tail4):
+	add	$4, %eax
+	RETURN
+
+L(exit_tail5):
+	add	$5, %eax
+	RETURN
+
+L(exit_tail6):
+	add	$6, %eax
+	RETURN
+
+L(exit_tail7):
+	add	$7, %eax
+	RETURN
+
+L(exit_tail8):
+	add	$8, %eax
+	RETURN
+
+L(exit_tail9):
+	add	$9, %eax
+	RETURN
+
+L(exit_tail10):
+	add	$10, %eax
+	RETURN
+
+L(exit_tail11):
+	add	$11, %eax
+	RETURN
+
+L(exit_tail12):
+	add	$12, %eax
+	RETURN
+
+L(exit_tail13):
+	add	$13, %eax
+	RETURN
+
+L(exit_tail14):
+	add	$14, %eax
+	RETURN
+
+L(exit_tail15):
+	add	$15, %eax
+	ret
+
+END (STRLEN)