auto import from //depot/cupcake/@135843
diff --git a/libc/arch-x86/string/strlen.S b/libc/arch-x86/string/strlen.S
new file mode 100644
index 0000000..4f04ffc
--- /dev/null
+++ b/libc/arch-x86/string/strlen.S
@@ -0,0 +1,20 @@
+/* $OpenBSD: strlen.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(strlen)
+ pushl %edi
+ movl 8(%esp),%edi /* string address */
+ cld /* set search forward */
+ xorl %eax,%eax /* set search for null terminator */
+ movl $-1,%ecx /* set search for lots of characters */
+ repne /* search! */
+ scasb
+ notl %ecx /* get length by taking complement */
+ leal -1(%ecx),%eax /* and subtracting one */
+ popl %edi
+ ret