Index: lib/libc/aarch64/sys/Makefile.inc
===================================================================
--- lib/libc/aarch64/sys/Makefile.inc
+++ lib/libc/aarch64/sys/Makefile.inc
@@ -4,8 +4,8 @@
 
 SRCS+=	__vdso_gettc.c
 
-#MDASM= ptrace.S
 MDASM=	cerror.S \
+	ptrace.S \
 	shmat.S \
 	sigreturn.S \
 	syscall.S \
@@ -15,6 +15,7 @@
 NOASM=	break.o \
 	exit.o \
 	getlogin.o \
+	ptrace.o \
 	sbrk.o \
 	sstk.o \
 	vfork.o \
Index: lib/libc/aarch64/sys/ptrace.S
===================================================================
--- /dev/null
+++ lib/libc/aarch64/sys/ptrace.S
@@ -0,0 +1,50 @@
+/*-
+ * Copyright (c) 2016 The FreeBSD Foundation
+ * All rights reserved.
+ *
+ * Portions of this software were developed by Konstantin Belousov
+ * 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.
+ */
+
+#include <machine/asm.h>
+__FBSDID("$FreeBSD$");
+#include <SYS.h>
+
+	.globl	_C_LABEL(__error)
+	.type	_C_LABEL(__error),@function
+
+ENTRY(ptrace)
+	stp	x0, x1, [sp, #-48]!
+	stp	x2, x3, [sp, #16]
+	stp	x29, lr, [sp, #32]
+	add	x29, sp, #32
+	bl	_C_LABEL(__error)
+	str	xzr, [x0]
+	ldp	x29, lr, [sp, #32]
+	ldp	x2, x3, [sp, #16]
+	ldp	x0, x1, [sp], #48
+	_SYSCALL(ptrace)
+	b.cs	cerror
+	ret
+END(ptrace)