diff --git a/tools/regression/filemon/Makefile b/tools/regression/filemon/Makefile
new file mode 100644
index 000000000000..dcad932b01a8
--- /dev/null
+++ b/tools/regression/filemon/Makefile
@@ -0,0 +1,26 @@
+# $FreeBSD$
+
+PROG=	filemontest
+
+NO_MAN=
+
+WARNS?=	6
+CFLAGS+= -I${.CURDIR}/../../../sys
+
+# Cannot use .OBJDIR -- 'filemontest' expects 'test_script.sh' in .
+test: ${PROG} clean-test
+	cd ${.CURDIR} ; \
+		for A in 1 2 3 4 5 6 7 8 9 0; do \
+		for B in 1 2 3 4 5 6 7 8 9 0; do \
+		for C in 1 2 3 4 5 6 7 8 9 0; do \
+			${.OBJDIR}/${PROG} ;\
+		done ;\
+		done ;\
+		done
+	@cd ${.CURDIR} ; set +e ; egrep '(Start|Stop) .*\.' filemon_log.* | \
+	    grep -q -v '\.[0-9][0-9][0-9][0-9][0-9][0-9]$$' || echo "Time stamp format OK"
+
+clean-test:
+	cd ${.CURDIR} ; rm -f filemon_log.*
+
+.include <bsd.prog.mk>
diff --git a/tools/regression/filemon/filemontest.c b/tools/regression/filemon/filemontest.c
new file mode 100644
index 000000000000..7962149837c6
--- /dev/null
+++ b/tools/regression/filemon/filemontest.c
@@ -0,0 +1,75 @@
+/*-
+ * Copyright (c) 2009-2011, Juniper Networks, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JUNIPER NETWORKS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL JUNIPER NETWORKS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/wait.h>
+#include <sys/ioctl.h>
+
+#include <dev/filemon/filemon.h>
+
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <err.h>
+
+/*
+ * This simple test of filemon expects a test script called
+ * "test_script.sh" in the cwd.
+ */
+
+int
+main(void) {
+	char log_name[] = "filemon_log.XXXXXX";
+	pid_t child;
+	int fm_fd, fm_log;
+
+	if ((fm_fd = open("/dev/filemon", O_RDWR)) == -1)
+		err(1, "open(\"/dev/filemon\", O_RDWR)");
+	if ((fm_log = mkstemp(log_name)) == -1)
+		err(1, "mkstemp(%s)", log_name);
+
+	if (ioctl(fm_fd, FILEMON_SET_FD, &fm_log) < 0)
+		err(1, "Cannot set filemon log file descriptor");
+
+	/* Set up these two fd's to close on exec. */
+	(void)fcntl(fm_fd, F_SETFD, FD_CLOEXEC);
+	(void)fcntl(fm_log, F_SETFD, FD_CLOEXEC);
+
+	if ((child = fork()) == 0) {
+		system("./test_script.sh");
+		return 0;
+	} else {
+		if (ioctl(fm_fd, FILEMON_SET_PID, &child) < 0)
+			err(1, "Cannot set filemon PID");
+		wait(&child);
+		close(fm_fd);
+//		printf("Results in %s\n", log_name);
+	}
+	return 0;
+}
diff --git a/tools/regression/filemon/test_script.sh b/tools/regression/filemon/test_script.sh
new file mode 100755
index 000000000000..df34ec4a3859
--- /dev/null
+++ b/tools/regression/filemon/test_script.sh
@@ -0,0 +1,43 @@
+#! /bin/sh
+#
+# Copyright (c) 2011, Juniper Networks, Inc.
+# 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 JUNIPER NETWORKS 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 JUNIPER NETWORKS 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.
+#
+# $FreeBSD$
+
+trap 'rm -f $f1 $f2; exit 1' 1 2 3 13 15
+echo shazbot > /dev/null
+f1=`mktemp /tmp/filemon_test.XXXXXX`
+f2=`mktemp /tmp/ed-script.XXXXXX`
+> $f1
+echo "One line to rule them all" >> $f1
+wc -l $f1 > /dev/null
+#	ed(1)'s /tmp/ed.* buffer file will be opened RW
+echo ',s/$/./g'	> $f2
+echo 'wq'	>>$f2
+ed -s $f1 < $f2
+#echo ",s/$/./\
+#w" | ed -s $f1
+#rm $f1 $f2
+uptime > /dev/null