diff --git a/lib/libthr/arch/powerpc/Makefile.inc b/lib/libthr/arch/powerpc/Makefile.inc
new file mode 100644
index 00000000000..6c0e24fe388
--- /dev/null
+++ b/lib/libthr/arch/powerpc/Makefile.inc
@@ -0,0 +1,3 @@
+# $FreeBSD$
+
+SRCS+=  _umtx_op_err.S
diff --git a/lib/libthr/arch/powerpc/include/pthread_md.h b/lib/libthr/arch/powerpc/include/pthread_md.h
index 939d7d2670e..0ed44058a7a 100644
--- a/lib/libthr/arch/powerpc/include/pthread_md.h
+++ b/lib/libthr/arch/powerpc/include/pthread_md.h
@@ -1,94 +1,96 @@
 /*-
  * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright 2004 by Peter Grehan. All rights reserved.
  *
  * 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.
  * 3. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
  *
  * $FreeBSD$
  */
 
 /*
  * Machine-dependent thread prototypes/definitions.
  */
 #ifndef _PTHREAD_MD_H_
 #define	_PTHREAD_MD_H_
 
 #include <stddef.h>
 #include <sys/types.h>
 
 #define	CPU_SPINWAIT
 
 #define	DTV_OFFSET		offsetof(struct tcb, tcb_dtv)
 #ifdef __powerpc64__
 #define	TP_OFFSET		0x7010
 #else
 #define	TP_OFFSET		0x7008
 #endif
 
 /*
  * Variant I tcb. The structure layout is fixed, don't blindly
  * change it.
  * %r2 (32-bit) or %r13 (64-bit) points to end of the structure.
  */
 struct tcb {
 	void			*tcb_dtv;
 	struct pthread		*tcb_thread;
 };
 
 static __inline void
 _tcb_set(struct tcb *tcb)
 {
 #ifdef __powerpc64__
 	__asm __volatile("mr 13,%0" ::
 	    "r"((uint8_t *)tcb + TP_OFFSET));
 #else
 	__asm __volatile("mr 2,%0" ::
 	    "r"((uint8_t *)tcb + TP_OFFSET));
 #endif
 }
 
 static __inline struct tcb *
 _tcb_get(void)
 {
         register struct tcb *tcb;
 
 #ifdef __powerpc64__
 	__asm __volatile("addi %0,13,%1" : "=r"(tcb) : "i"(-TP_OFFSET));
 #else
 	__asm __volatile("addi %0,2,%1" : "=r"(tcb) : "i"(-TP_OFFSET));
 #endif
 
 	return (tcb);
 }
 
 static __inline struct pthread *
 _get_curthread(void)
 {
 	if (_thr_initial)
 		return (_tcb_get()->tcb_thread);
 	return (NULL);
 }
 
+#define	HAS__UMTX_OP_ERR	1
+
 #endif /* _PTHREAD_MD_H_ */
diff --git a/lib/libthr/arch/powerpc/powerpc/_umtx_op_err.S b/lib/libthr/arch/powerpc/powerpc/_umtx_op_err.S
new file mode 100644
index 00000000000..23b8a44d086
--- /dev/null
+++ b/lib/libthr/arch/powerpc/powerpc/_umtx_op_err.S
@@ -0,0 +1,41 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2019 Brandon Bergren <git@bdragon.rtk0.net>
+ *
+ * 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>
+#include <sys/syscall.h>
+
+	.text
+	.align 2
+ENTRY(_umtx_op_err)
+	li	0,SYS__umtx_op
+	sc
+	blr
+END(_umtx_op_err)
+
+	.section .note.GNU-stack,"",%progbits