diff --git a/man/man8/zfs-mount.8 b/man/man8/zfs-mount.8
index 40adf79059..b6f033297d 100644
--- a/man/man8/zfs-mount.8
+++ b/man/man8/zfs-mount.8
@@ -47,7 +47,7 @@
 .Nm zfs
 .Cm unmount
 .Op Fl fu
-.Fl a Ns | Ns Ar filesystem Ns | Ns Ar mountpoint
+.Fl a Oo filesystem Oc | Oo Fl A Oc Ar filesystem | Ar mountpoint
 .
 .Sh DESCRIPTION
 .Bl -tag -width ""
@@ -115,21 +115,26 @@ be mounted (e.g. redacted datasets).
 .Nm zfs
 .Cm unmount
 .Op Fl fu
-.Fl a Ns | Ns Ar filesystem Ns | Ns Ar mountpoint
+.Fl a Oo filesystem Oc | Oo Fl A Oc Ar filesystem | Ar mountpoint
 .Xc
 Unmounts currently mounted ZFS file systems.
 .Bl -tag -width "-a"
-.It Fl a
-Unmount all available ZFS file systems.
+.It Fl a Op filesystem
+Unmount the specified filesystem and its children, provided they are available.
+If no filesystem is specified,
+then all available ZFS file systems are unmounted.
 Invoked automatically as part of the shutdown process.
-.It Fl f
-Forcefully unmount the file system, even if it is currently in use.
-This option is not supported on Linux.
-.It Fl u
-Unload keys for any encryption roots unmounted by this command.
+.It Fl A Ar filesystem
+Unmount the specified filesystem and its children, provided they are available.
+Note: datasets with the `canmount=noauto` property will also be unmounted.
 .It Ar filesystem Ns | Ns Ar mountpoint
 Unmount the specified filesystem.
 The command can also be given a path to a ZFS file system mount point on the
 system.
+.It Fl u
+Unload keys for any encryption roots unmounted by this command.
+.It Fl f
+Forcefully unmount the file system, even if it is currently in use.
+This option is not supported on Linux.
 .El
 .El
diff --git a/tests/runfiles/common.run b/tests/runfiles/common.run
index eddbf9a1dc..b3be16edc1 100644
--- a/tests/runfiles/common.run
+++ b/tests/runfiles/common.run
@@ -305,7 +305,8 @@ tags = ['functional', 'cli_root', 'zfs_unload-key']
 tests = ['zfs_unmount_001_pos', 'zfs_unmount_002_pos', 'zfs_unmount_003_pos',
     'zfs_unmount_004_pos', 'zfs_unmount_005_pos', 'zfs_unmount_006_pos',
     'zfs_unmount_007_neg', 'zfs_unmount_008_neg', 'zfs_unmount_009_pos',
-    'zfs_unmount_all_001_pos', 'zfs_unmount_nested', 'zfs_unmount_unload_keys']
+    'zfs_unmount_all_001_pos', 'zfs_unmount_all_002_pos', 'zfs_unmount_nested',
+    'zfs_unmount_unload_keys']
 tags = ['functional', 'cli_root', 'zfs_unmount']
 
 [tests/functional/cli_root/zfs_unshare]
diff --git a/tests/zfs-tests/tests/Makefile.am b/tests/zfs-tests/tests/Makefile.am
index 483f00d9e8..0277afb1e4 100644
--- a/tests/zfs-tests/tests/Makefile.am
+++ b/tests/zfs-tests/tests/Makefile.am
@@ -923,6 +923,7 @@ nobase_dist_datadir_zfs_tests_tests_SCRIPTS += \
 	functional/cli_root/zfs_unmount/zfs_unmount_008_neg.ksh \
 	functional/cli_root/zfs_unmount/zfs_unmount_009_pos.ksh \
 	functional/cli_root/zfs_unmount/zfs_unmount_all_001_pos.ksh \
+	functional/cli_root/zfs_unmount/zfs_unmount_all_002_pos.ksh \
 	functional/cli_root/zfs_unmount/zfs_unmount_nested.ksh \
 	functional/cli_root/zfs_unmount/zfs_unmount_unload_keys.ksh \
 	functional/cli_root/zfs_unshare/cleanup.ksh \
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_007_neg.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_007_neg.ksh
index 1a8665b86e..ee8d30db4e 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_007_neg.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_007_neg.ksh
@@ -37,7 +37,6 @@
 #	Try each 'zfs unmount' with inapplicable scenarios to make sure
 #	it returns an error. include:
 #		* Multiple filesystem|mountpoint specified
-#		* '-a', but also with a specific filesystem|mountpoint.
 #
 # STRATEGY:
 #	1. Create an array of parameters
@@ -54,7 +53,7 @@ for fs in $multifs ; do
 	datasets="$datasets $TESTPOOL/$fs"
 done
 
-set -A args "$unmountall $TESTPOOL/$TESTFS" \
+set -A args "$unmountall $datasets" \
 	"$unmountcmd $datasets"
 
 function setup_all
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_008_neg.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_008_neg.ksh
index 3524efcd07..a730a0e7b4 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_008_neg.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_008_neg.ksh
@@ -73,7 +73,7 @@ log_onexit cleanup
 fs=$TESTPOOL/$TESTFS
 vol=$TESTPOOL/vol.$$
 snap=$TESTPOOL/$TESTFS@snap.$$
-set -A badargs "A" "-A" "F" "-F" "-" "-x" "-?"
+set -A badargs "A" "F" "-F" "-" "-x" "-?"
 
 if ! ismounted $fs; then
 	log_must zfs mount $fs
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_all_001_pos.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_all_001_pos.ksh
index f98d48ad92..8ae80663ad 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_all_001_pos.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_all_001_pos.ksh
@@ -41,8 +41,8 @@
 #       2. Create zfs filesystems within the given pools.
 #       3. Mount all the filesystems.
 #       4. Verify that 'zfs unmount -a[f]' command succeed,
-#	   and all available ZFS filesystems are unmounted.
-#	5. Verify that 'zfs mount' is identical with 'df -F zfs'
+#          and all available ZFS filesystems are unmounted.
+#       5. Verify that 'zfs mount' is identical with 'df -F zfs'
 #
 
 verify_runnable "both"
diff --git a/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_all_002_pos.ksh b/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_all_002_pos.ksh
new file mode 100644
index 0000000000..fcd34b201c
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/cli_root/zfs_unmount/zfs_unmount_all_002_pos.ksh
@@ -0,0 +1,203 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or https://opensource.org/licenses/CDDL-1.0.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
+# Use is subject to license terms.
+#
+
+#
+# Copyright (c) 2016 by Delphix. All rights reserved.
+#
+
+. $STF_SUITE/tests/functional/cli_root/zfs_mount/zfs_mount.kshlib
+. $STF_SUITE/tests/functional/cli_root/zfs_unmount/zfs_unmount.kshlib
+
+#
+# DESCRIPTION:
+#       Verify that 'zfs unmount -a[f]' succeeds as root.
+#
+# STRATEGY:
+#       1. Create a group of pools with specified vdev.
+#       2. Create zfs filesystems within the given pools.
+#       3. Mount all the filesystems.
+#       4. Verify that 'zfs unmount -a filesystem' command succeed,
+#          and the related available ZFS filesystems are unmounted,
+#          and the unrelated ZFS filesystems remain mounted
+#       5. Verify that 'zfs mount' is identical with 'df -F zfs'
+#
+
+verify_runnable "both"
+
+set -A fs "$TESTFS" "$TESTFS1"
+set -A ctr "" "$TESTCTR" "$TESTCTR1" "$TESTCTR/$TESTCTR1"
+set -A vol "$TESTVOL" "$TESTVOL1"
+
+# Test the mounted state of root dataset (testpool/testctr)
+typeset mnt=$TESTCTR
+
+function setup_all
+{
+	typeset -i i=0
+	typeset -i j=0
+	typeset path
+
+	while (( i < ${#ctr[*]} )); do
+
+		path=${TEST_BASE_DIR%%/}/testroot$$/$TESTPOOL
+		if [[ -n ${ctr[i]} ]]; then
+			path=$path/${ctr[i]}
+
+			setup_filesystem "$DISKS" "$TESTPOOL" \
+				"${ctr[i]}" "$path" \
+				"ctr"
+		fi
+
+		if is_global_zone ; then
+			j=0
+			while (( j < ${#vol[*]} )); do
+				setup_filesystem "$DISKS" "$TESTPOOL" \
+				"${ctr[i]}/${vol[j]}" \
+					"$path/${vol[j]}" \
+					"vol"
+				((j = j + 1))
+			done
+		fi
+		j=0
+		while (( j < ${#fs[*]} )); do
+			setup_filesystem "$DISKS" "$TESTPOOL" \
+				"${ctr[i]}/${fs[j]}" \
+				"$path/${fs[j]}"
+			((j = j + 1))
+		done
+
+		((i = i + 1))
+	done
+
+	return 0
+}
+
+function cleanup_all
+{
+	typeset -i i=0
+	typeset -i j=0
+
+	((i = ${#ctr[*]} - 1))
+
+	while (( i >= 0 )); do
+		if is_global_zone ; then
+			j=0
+			while (( j < ${#vol[*]} )); do
+				cleanup_filesystem "$TESTPOOL" \
+					"${ctr[i]}/${vol[j]}"
+				((j = j + 1))
+			done
+		fi
+
+		j=0
+		while (( j < ${#fs[*]} )); do
+			cleanup_filesystem "$TESTPOOL" \
+				"${ctr[i]}/${fs[j]}"
+			((j = j + 1))
+		done
+
+		[[ -n ${ctr[i]} ]] && \
+			cleanup_filesystem "$TESTPOOL" "${ctr[i]}"
+
+		((i = i - 1))
+	done
+
+	[[ -d ${TEST_BASE_DIR%%/}/testroot$$ ]] && \
+		rm -rf ${TEST_BASE_DIR%%/}/testroot$$
+}
+
+#
+# This function verifies that the file systems in $mnt are unmounted.
+# Next, it ensures that all other file systems in remain mounted.
+#
+function verify_related
+{
+	typeset -i i=0
+	typeset -i j=0
+	typeset path
+
+	while (( i < ${#ctr[*]} )); do
+
+		if { [[ ${ctr[i]} == $mnt ]] || [[ ${ctr[i]} == $mnt/* ]] }; then
+			logfunc=log_must
+		else
+			logfunc=log_mustnot
+		fi
+
+		path=$TESTPOOL
+		[[ -n ${ctr[i]} ]] && \
+			path=$path/${ctr[i]}
+
+		if is_global_zone ; then
+			j=0
+			while (( j < ${#vol[*]} )); do
+				log_must unmounted "$path/${vol[j]}"
+				((j = j + 1))
+			done
+		fi
+
+		j=0
+		while (( j < ${#fs[*]} )); do
+			$logfunc unmounted "$path/${fs[j]}"
+			((j = j + 1))
+		done
+
+		$logfunc unmounted "$path"
+
+		((i = i + 1))
+	done
+
+	return 0
+}
+
+
+log_assert "Verify that 'zfs $unmountall $TESTPOOL/$mnt' succeeds as root, " \
+	"and all the related available ZFS filesystems are unmounted."
+
+log_onexit cleanup_all
+
+log_must setup_all
+
+typeset opt
+for opt in "-a" "-fa"; do
+	export __ZFS_POOL_RESTRICT="$TESTPOOL"
+	log_must zfs $mountall
+	unset __ZFS_POOL_RESTRICT
+
+	export __ZFS_POOL_RESTRICT="$TESTPOOL"
+	log_must zfs unmount $opt $TESTPOOL/$mnt
+	unset __ZFS_POOL_RESTRICT
+
+	log_must verify_related
+	log_note "Verify that 'zfs $mountcmd' will display " \
+	"all available ZFS filesystems related to '$TESTPOOL/$mnt' are unmounted."
+	log_must verify_mount_display
+
+done
+
+log_pass "'zfs mount -[f]a $TESTPOOL/$mnt' succeeds as root, " \
+	"and all the related available ZFS filesystems are unmounted."