Index: head/lib/libc/amd64/string/bzero.S
===================================================================
--- head/lib/libc/amd64/string/bzero.S
+++ head/lib/libc/amd64/string/bzero.S
@@ -1,46 +1,7 @@
-/*
- * Written by J.T. Conklin <jtc@NetBSD.org>.
- * Public domain.
- * Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com>
- */
+/*	$FreeBSD */
 
 #include <machine/asm.h>
 __FBSDID("$FreeBSD$");
 
-#if 0
-	RCSID("$NetBSD: bzero.S,v 1.2 2003/07/26 19:24:38 salo Exp $")
-#endif
-
-ENTRY(bzero)
-	cld				/* set fill direction forward */
-	xorq	%rax,%rax		/* set fill data to 0 */
-
-	/*
-	 * if the string is too short, it's really not worth the overhead
-	 * of aligning to word boundries, etc.  So we jump to a plain
-	 * unaligned set.
-	 */
-	cmpq	$16,%rsi
-	jb	L1
-
-	movq	%rdi,%rcx		/* compute misalignment */
-	negq	%rcx
-	andq	$7,%rcx
-	subq	%rcx,%rsi
-	rep				/* zero until word aligned */
-	stosb
-
-	movq	%rsi,%rcx		/* zero by words */
-	shrq	$3,%rcx
-	andq	$7,%rsi
-	rep
-	stosq
-
-L1:	movq	%rsi,%rcx		/* zero remainder by bytes */
-	rep
-	stosb
-
-	ret
-END(bzero)
-
-	.section .note.GNU-stack,"",%progbits
+#define BZERO
+#include "memset.S"
Index: head/lib/libc/amd64/string/memset.S
===================================================================
--- head/lib/libc/amd64/string/memset.S
+++ head/lib/libc/amd64/string/memset.S
@@ -1,63 +1,77 @@
-/*
- * Written by J.T. Conklin <jtc@NetBSD.org>.
- * Public domain.
- * Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com>
+/*-
+ * Copyright (c) 2018 The FreeBSD Foundation
+ *
+ * This software was developed by Mateusz Guzik <mjg@FreeBSD.org>
+ * under sponsorship from the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ *
+ * $FreeBSD$
  */
 
 #include <machine/asm.h>
 __FBSDID("$FreeBSD$");
 
-#if 0
-	RCSID("$NetBSD: memset.S,v 1.3 2004/02/26 20:50:06 drochner Exp $")
-#endif
-
-ENTRY(memset)
-	movq	%rsi,%rax
-	andq	$0xff,%rax
+.macro MEMSET bzero
+.if \bzero == 1
+	movq	%rsi,%rcx
+	movq	%rsi,%rdx
+	xorl	%eax,%eax
+.else
+	movq	%rdi,%r9
 	movq	%rdx,%rcx
-	movq	%rdi,%r11
-
-	cld				/* set fill direction forward */
-
-	/*
-	 * if the string is too short, it's really not worth the overhead
-	 * of aligning to word boundries, etc.  So we jump to a plain
-	 * unaligned set.
-	 */
-	cmpq	$0x0f,%rcx
-	jle	L1
-
-	movb	%al,%ah			/* copy char to all bytes in word */
-	movl	%eax,%edx
-	sall	$16,%eax
-	orl	%edx,%eax
-
-	movl	%eax,%edx
-	salq	$32,%rax
-	orq	%rdx,%rax
-
-	movq	%rdi,%rdx		/* compute misalignment */
-	negq	%rdx
-	andq	$7,%rdx
-	movq	%rcx,%r8
-	subq	%rdx,%r8
-
-	movq	%rdx,%rcx		/* set until word aligned */
+	movzbq	%sil,%r8
+	movabs	$0x0101010101010101,%rax
+	imulq	%r8,%rax
+.endif
+	cmpq	$15,%rcx
+	jbe	1f
+	shrq	$3,%rcx
 	rep
-	stosb
-
-	movq	%r8,%rcx
-	shrq	$3,%rcx			/* set by words */
-	rep
 	stosq
-
-	movq	%r8,%rcx		/* set remainder by bytes */
+	movq	%rdx,%rcx
 	andq	$7,%rcx
-L1:	rep
+	jne	1f
+.if \bzero == 0
+	movq	%r9,%rax
+.endif
+	ret
+1:
+	rep
 	stosb
-	movq	%r11,%rax
-
+.if \bzero == 0
+	movq	%r9,%rax
+.endif
 	ret
+.endm
+
+#ifndef BZERO
+ENTRY(memset)
+	MEMSET bzero=0
 END(memset)
+#else
+ENTRY(bzero)
+	MEMSET bzero=1
+END(bzero)
+#endif
 
 	.section .note.GNU-stack,"",%progbits