diff --git a/.arclint b/.arclint
index 31bda09b1a83..5078cba32c37 100644
--- a/.arclint
+++ b/.arclint
@@ -9,7 +9,8 @@
       "type": "spelling"
     },
     "chmod": {
-      "type": "chmod"
+      "type": "chmod",
+      "exclude": "(/tests/)"
     },
     "merge-conflict": {
       "type": "merge-conflict"
diff --git a/usr.bin/sponge/Makefile b/usr.bin/sponge/Makefile
new file mode 100644
index 000000000000..d71927ab8691
--- /dev/null
+++ b/usr.bin/sponge/Makefile
@@ -0,0 +1,8 @@
+# $FreeBSD$
+
+PROG=	sponge
+
+HAS_TESTS=
+SUBDIR.${MK_TESTS}+= tests
+
+.include <bsd.prog.mk>
diff --git a/usr.bin/sponge/sponge.1 b/usr.bin/sponge/sponge.1
new file mode 100644
index 000000000000..0b9860c03471
--- /dev/null
+++ b/usr.bin/sponge/sponge.1
@@ -0,0 +1,75 @@
+.\"	Eitan Adler.  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.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd November 1, 2017
+.Dt SPONGE 1
+.Os
+.Sh NAME
+.Nm sponge
+.Nd buffer stdin and write to stdout
+.Sh SYNOPSIS
+.Nm
+.Op Fl a
+.Ar filename
+.Sh DESCRIPTION
+The
+.Nm
+utility reads standard in until complete, then opens
+the output file and writes to it.
+This makes it useful in pipelines that read a file and then write to it.
+These options are available:
+.Bl -tag -width indent
+.It Fl a
+Open
+.Ar filename
+in append mode.
+.El
+.Pp
+If an attempt to allocate memory fails,
+.Nm
+fails without output.
+The file is written even if earlier components
+of the pipeline failed.
+.Sh SEE ALSO
+.Xr builtin 1 ,
+.Xr csh 1 ,
+.Xr getrusage 2 ,
+.Xr tee 1 ,
+.Xr wait 2
+.Sh EXIT STATUS
+.Ex -std
+.Sh EXAMPLES
+A
+.Pa file
+can be be sorted "in place" by executing
+.Cm sort file | sponge file
+.Sh HISTORY
+The
+.Nm
+utility was written by
+.An Eitan Adler Aq Mt eadler@FreeBSD.org
+and first appeared
+in
+.Fx 12.0 .
diff --git a/usr.bin/sponge/sponge.c b/usr.bin/sponge/sponge.c
new file mode 100644
index 000000000000..0200bc2dc805
--- /dev/null
+++ b/usr.bin/sponge/sponge.c
@@ -0,0 +1,189 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2017 Eitan Adler
+ *
+ * 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 REGENTS 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 REGENTS 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 <err.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <getopt.h>
+#include <unistd.h>
+#include <sys/uio.h>
+
+#define DEFAULT_BUF_SIZE 16384
+#define DEFAULT_BUF_CNT 12
+
+static int flag_append = 0;
+
+static void usage(void);
+static void *safe_malloc(size_t size);
+static void *safe_calloc(size_t count, size_t size);
+static void *safe_reallocf(void *ptr, size_t size);
+
+static void *
+safe_malloc(size_t size)
+{
+	void *ret;
+
+	ret = malloc(size);
+	if (ret == NULL) {
+		err(1, "malloc failed");
+	}
+	return (ret);
+}
+
+static void *
+safe_calloc(size_t count, size_t size)
+{
+	void *ret;
+
+	ret = calloc(count, size);
+	if (ret == NULL) {
+		err(1, "calloc failed");
+	}
+	return (ret);
+}
+
+static void *
+safe_reallocf(void *ptr, size_t size)
+{
+	void *ret;
+
+	ret = reallocf(ptr, size);
+	if (ret == NULL) {
+		err(1, "reallocf failed");
+	}
+	return (ret);
+}
+
+static void
+usage(void)
+{
+	fprintf(stderr, "usage: sponge [-a] filename\n");
+}
+
+int
+main(int argc, char* argv[])
+{
+	struct iovec *iov;
+	char *buf;
+	char *outfile;
+	ssize_t i;
+	size_t bufcnt;
+	size_t whichbuf;
+	size_t bufremain;
+	long maxiovec;
+	int fd;
+	int openflags = O_WRONLY;
+	int opt;
+
+	while ((opt = getopt(argc, argv, "ah")) != -1) {
+		switch (opt) {
+		case 'a':
+			flag_append = 1;
+			break;
+		case 'h':
+			usage();
+			exit(0);
+		case '?':
+		default:
+			usage();
+			exit(1);
+		}
+	}
+
+	if (optind < argc) {
+                outfile = argv[optind];
+	}
+
+
+	bufcnt = DEFAULT_BUF_CNT;
+	whichbuf = 0;
+	iov = safe_calloc(bufcnt, sizeof(*iov));
+
+	for (;;) {
+		buf = safe_malloc(DEFAULT_BUF_SIZE);
+		i = read(STDIN_FILENO, buf, DEFAULT_BUF_SIZE);
+		if (whichbuf == bufcnt) {
+			bufcnt *= 2;
+			iov = safe_reallocf(iov, bufcnt * sizeof(*iov));
+		}
+		if (i < 0) {
+			err(1, "read failed");
+		}
+		if (i == 0) {
+			free(buf);
+			break;
+		}
+		iov[whichbuf].iov_base = buf;
+		iov[whichbuf].iov_len = i;
+		whichbuf++;
+	}
+
+	if (outfile) {
+		if (flag_append) {
+			openflags |= O_APPEND;
+		} else {
+			openflags |= O_TRUNC;
+		}
+		fd = open(outfile, openflags);
+	}
+	else {
+		fd = STDOUT_FILENO;
+	}
+
+	if (fd < 0) {
+		err(1, "failed to open");
+	}
+
+	maxiovec = sysconf(_SC_IOV_MAX);
+	if (maxiovec == -1) {
+		maxiovec =  _XOPEN_IOV_MAX;
+	}
+	bufcnt = whichbuf;
+	bufremain = bufcnt;
+
+	while (bufremain > 0) {
+		whichbuf = (bufremain < maxiovec) ? bufremain : maxiovec;
+		bufremain -= whichbuf;
+
+		i = writev(fd, iov, whichbuf);
+		if (i < 0) {
+			err(1, "failed to write");
+		}
+	}
+
+	if (outfile) {
+		i = close(fd);
+		if (i < 0) {
+			err(1, "failed to close");
+		}
+	}
+}
diff --git a/usr.bin/sponge/tests/Makefile b/usr.bin/sponge/tests/Makefile
new file mode 100644
index 000000000000..f247b8bacdd0
--- /dev/null
+++ b/usr.bin/sponge/tests/Makefile
@@ -0,0 +1,9 @@
+# $FreeBSD$
+
+PACKAGE=	${TESTBASE}/usr.bin/sponge
+
+TESTSDIR=	${TESTSBASE}/usr.bin/sponge/tests
+
+ATF_TESTS_SH=	cp_test
+
+.include <bsd.test.mk>
diff --git a/usr.bin/sponge/tests/Makefile.depend b/usr.bin/sponge/tests/Makefile.depend
new file mode 100644
index 000000000000..c062f6026d94
--- /dev/null
+++ b/usr.bin/sponge/tests/Makefile.depend
@@ -0,0 +1,18 @@
+# $FreeBSD$
+# Autogenerated - do NOT edit!
+
+DIRDEPS = \
+	gnu/lib/csu \
+	include \
+	include/xlocale \
+	lib/${CSU_DIR} \
+	lib/atf/libatf-c \
+	lib/libc \
+	lib/libcompiler_rt \
+
+
+.include <dirdeps.mk>
+
+.if ${DEP_RELDIR} == ${_DEP_RELDIR}
+# local dependencies - needed for -jN in clean tree
+.endif
diff --git a/usr.bin/sponge/tests/sponge_test.sh b/usr.bin/sponge/tests/sponge_test.sh
new file mode 100755
index 000000000000..feb1715751ee
--- /dev/null
+++ b/usr.bin/sponge/tests/sponge_test.sh
@@ -0,0 +1,48 @@
+# $FreeBSD$
+#
+# SPDX-License-Identifier: BSD-2-Clause
+#
+# Copyright 2017 Eitan Adler
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright
+#   notice, this list of conditions and the following disclaimer.
+# * 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 HOLDERS 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 COPYRIGHT
+# OWNER 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.
+
+atf_test_case simple
+simple_body() {
+  printf 'd\ne\na\n' >| x
+  printf 'a\nd\ne\n' >| y
+  sort x | sponge x
+
+  atf_check -s exit:0 -o empty -e empty 'sort x | sponge x'
+
+  if ! cmp -s x y; then
+    echo "x and y differ, but they should be equal"
+    diff -u x y
+    atf_fail "Original and copy do not match"
+  fi
+
+}
+
+atf_init_test_cases() {
+  atf_add_test_case simple
+}
diff --git a/usr.bin/tee/tee.1 b/usr.bin/tee/tee.1
index 546c489377c9..1dc0fbcfdd50 100644
--- a/usr.bin/tee/tee.1
+++ b/usr.bin/tee/tee.1
@@ -72,6 +72,8 @@ utility takes the default action for all signals,
 except in the event of the
 .Fl i
 option.
+.Sh SEE ALSO
+.Xr sponge 1
 .Sh EXIT STATUS
 .Ex -std
 .Sh STANDARDS