Index: libexec/rc/rc.d/jail
===================================================================
--- libexec/rc/rc.d/jail
+++ libexec/rc/rc.d/jail
@@ -119,12 +119,16 @@
 		return
 	fi
 	eval _jconf=\"\${jail_${_jv}_conf:-/etc/jail.${_j}.conf}\"
+	eval _jconfdir=\"\/etc/jail.d/${_j}.conf\"
 	eval _rootdir=\"\$jail_${_jv}_rootdir\"
 	eval _hostname=\"\$jail_${_jv}_hostname\"
 	if [ -z "$_rootdir" -o \
 	     -z "$_hostname" ]; then
 		if [ -r "$_jconf" ]; then
 			_conf="$_jconf"
+			return 0
+		elif [ -r "$_jconfdir" ]; then
+			_conf="$_jconfdir"
 			return 0
 		elif [ -r "$jail_conf" ]; then
 			_conf="$jail_conf"
Index: share/man/man5/rc.conf.5
===================================================================
--- share/man/man5/rc.conf.5
+++ share/man/man5/rc.conf.5
@@ -3852,8 +3852,11 @@
 The configuration filename used by
 .Xr jail 8
 utility.
-The default value is
-.Pa /etc/jail.conf .
+The default values are
+.Pa /etc/jail.conf ,
+.Pa /etc/jail. Ns Ao Ar jname Ac Ns Va .conf 
+and
+.Pa /etc/jail.d/ Ns Ao Ar jname Ac Ns Va .conf .
 .It Va jail_parallel_start
 .Pq Vt bool
 If set to
Index: usr.sbin/jail/jail.8
===================================================================
--- usr.sbin/jail/jail.8
+++ usr.sbin/jail/jail.8
@@ -143,8 +143,11 @@
 .It Fl f Ar conf_file
 Use configuration file
 .Ar conf_file
-instead of the default
-.Pa /etc/jail.conf .
+instead of the defaults
+.Pa /etc/jail.conf ,
+.Pa /etc/jail. Ns Ao Ar jname Ac Ns Va .conf 
+and
+.Pa /etc/jail.d/ Ns Ao Ar jname Ac Ns Va .conf .
 .It Fl h
 Resolve the
 .Va host.hostname