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