Index: lib/libc/include/libc_private.h
===================================================================
--- lib/libc/include/libc_private.h
+++ lib/libc/include/libc_private.h
@@ -331,6 +331,7 @@
 int		__sys_clock_nanosleep(__clockid_t, int,
 		    const struct timespec *, struct timespec *);
 int		__sys_close(int);
+int		__sys_close_range(unsigned, unsigned, int);
 int		__sys_connect(int, const struct sockaddr *, __socklen_t);
 int		__sys_fcntl(int, int, ...);
 int		__sys_fdatasync(int);
Index: lib/libc/sys/Makefile.inc
===================================================================
--- lib/libc/sys/Makefile.inc
+++ lib/libc/sys/Makefile.inc
@@ -45,6 +45,7 @@
 PSEUDO+= _getdirentries.o
 
 SRCS+= brk.c
+SRCS+= closefrom.c
 SRCS+= pipe.c
 SRCS+= shm_open.c
 SRCS+= vadvise.c
Index: lib/libc/sys/closefrom.c
===================================================================
--- /dev/null
+++ lib/libc/sys/closefrom.c
@@ -0,0 +1,50 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2020 Kyle Evans <kevans@FreeBSD.org>
+ *
+ * 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 COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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 <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include "libc_private.h"
+
+__weak_reference(closefrom, _closefrom);
+__weak_reference(closefrom, __sys_closefrom);
+
+#define	CLOSE_RANGE_OSREL		1300091
+
+void
+closefrom(int lowfd)
+{
+
+	if (__getosreldate() >= CLOSE_RANGE_OSREL)
+		__sys_close_range(lowfd, ~0U, 0);
+	else
+		/* Fallback to closefrom(2) on older kernels. */
+		syscall(SYS_freebsd12_closefrom, lowfd);
+}
Index: sys/compat/freebsd32/syscalls.master
===================================================================
--- sys/compat/freebsd32/syscalls.master
+++ sys/compat/freebsd32/syscalls.master
@@ -980,7 +980,7 @@
 507	AUE_JAIL_SET	STD	{ int freebsd32_jail_set(struct iovec32 *iovp, \
 				    unsigned int iovcnt, int flags); }
 508	AUE_JAIL_REMOVE	NOPROTO	{ int jail_remove(int jid); }
-509	AUE_CLOSEFROM	NOPROTO	{ int closefrom(int lowfd); }
+509	AUE_CLOSEFROM	COMPAT12|NOPROTO	{ int closefrom(int lowfd); }
 510	AUE_SEMCTL	NOSTD { int freebsd32_semctl(int semid, int semnum, \
 				    int cmd, union semun32 *arg); }
 511	AUE_MSGCTL	NOSTD	{ int freebsd32_msgctl(int msqid, int cmd, \
Index: sys/kern/kern_descrip.c
===================================================================
--- sys/kern/kern_descrip.c
+++ sys/kern/kern_descrip.c
@@ -1372,17 +1372,18 @@
 	return (kern_close_range(td, uap->lowfd, uap->highfd));
 }
 
+#ifdef COMPAT_FREEBSD12
 /*
  * Close open file descriptors.
  */
 #ifndef _SYS_SYSPROTO_H_
-struct closefrom_args {
+struct freebsd12_closefrom_args {
 	int	lowfd;
 };
 #endif
 /* ARGSUSED */
 int
-sys_closefrom(struct thread *td, struct closefrom_args *uap)
+freebsd12_closefrom(struct thread *td, struct freebsd12_closefrom_args *uap)
 {
 	u_int lowfd;
 
@@ -1395,6 +1396,7 @@
 	lowfd = MAX(0, uap->lowfd);
 	return (kern_close_range(td, lowfd, ~0U));
 }
+#endif	/* COMPAT_FREEBSD12 */
 
 #if defined(COMPAT_43)
 /*
Index: sys/kern/syscalls.master
===================================================================
--- sys/kern/syscalls.master
+++ sys/kern/syscalls.master
@@ -2776,7 +2776,7 @@
 		    int jid
 		);
 	}
-509	AUE_CLOSEFROM	STD {
+509	AUE_CLOSEFROM	COMPAT12 {
 		int closefrom(
 		    int lowfd
 		);
Index: tools/build/depend-cleanup.sh
===================================================================
--- tools/build/depend-cleanup.sh
+++ tools/build/depend-cleanup.sh
@@ -34,3 +34,5 @@
 # Date      Rev      Description
 # 20200310  r358851  rename of openmp's ittnotify_static.c to .cpp
 clean_dep lib/libomp ittnotify_static c
+# 2020041X  rXXXXXX  closefrom
+clean_dep lib/libc   closefrom c