auto import from //depot/cupcake/@135843
diff --git a/libc/arch-x86/string/memchr.S b/libc/arch-x86/string/memchr.S
new file mode 100644
index 0000000..d6bcbe6
--- /dev/null
+++ b/libc/arch-x86/string/memchr.S
@@ -0,0 +1,26 @@
+/* $OpenBSD: memchr.S,v 1.3 2005/08/07 11:30:38 espie Exp $ */
+/*
+ * Written by J.T. Conklin <jtc@netbsd.org>.
+ * Public domain.
+ */
+
+#include <machine/asm.h>
+
+ENTRY(memchr)
+ pushl %edi
+ movl 8(%esp),%edi /* string address */
+ movl 12(%esp),%eax /* set character to search for */
+ movl 16(%esp),%ecx /* set length of search */
+ testl %ecx,%ecx /* test for len == 0 */
+ jz L1
+ cld /* set search forward */
+ repne /* search! */
+ scasb
+ jne L1 /* scan failed, return null */
+ leal -1(%edi),%eax /* adjust result of scan */
+ popl %edi
+ ret
+ .align 2,0x90
+L1: xorl %eax,%eax
+ popl %edi
+ ret