Index: usr.sbin/mergemaster/mergemaster.8
===================================================================
--- usr.sbin/mergemaster/mergemaster.8
+++ usr.sbin/mergemaster/mergemaster.8
@@ -389,6 +389,11 @@
 # Files to always avoid comparing
 #IGNORE_FILES='/etc/motd /etc/printcap foo bar'
 #
+# Files that are allowed to fail type checking if they are a symbolic link to
+# the correct type. /boot is always allowed to be a symbolic link. If a
+# destination directory is specified, the link must not point outside of it.
+#ALLOW_SYMLINK='/boot /var' # separate multiple files with spaces
+#
 # Additional options for diff.  This will get unset when using -s.
 #DIFF_OPTIONS='-Bb'	# Ignore changes in whitespace
 #
Index: usr.sbin/mergemaster/mergemaster.sh
===================================================================
--- usr.sbin/mergemaster/mergemaster.sh
+++ usr.sbin/mergemaster/mergemaster.sh
@@ -353,6 +353,15 @@
   esac
 done
 
+# Resolve a potentially relative destination directory which is
+# required to later catch symbolic links pointing outside of it
+if [ -n "${DESTDIR}" ]; then
+  DESTDIR=`realpath "${DESTDIR}"`
+  if [ $? != 0 ]; then
+    exit 1
+  fi
+fi
+
 if [ -n "$AUTO_RUN" ]; then
   if [ -n "$FREEBSD_ID" -o -n "$AUTO_UPGRADE" -o -n "$AUTO_INSTALL" ]; then
     echo ''
@@ -1034,6 +1043,28 @@
     TEMPROOT_TYPE=`echo $TEMPROOT_TYPE | tr [:upper:] [:lower:]`
     INSTALLED_TYPE=`echo $INSTALLED_TYPE | tr [:upper:] [:lower:]`
 
+    # Ignore the type mismatch for user specified files if the installed
+    # file is of type symlink and the following conditions are met:
+    # - installed type is symlink
+    # - symlink target has the correct type
+    # - if DESTDIR is set, symlink does not point outside of it
+    # - file is listed in ALLOW_SYMLINK
+    # Always allow /boot to be a symlink to handle bsdinstall linking /boot
+    # to an unencrypted boot volume
+    if [ "${INSTALLED_TYPE}" = 'symbolic link' ]; then
+      SYMLINK_TARGET=`realpath "${DESTDIR}${COMPFILE#.}"`
+      SYMLINK_TARGET_TYPE=`stat -f '%HT' "${SYMLINK_TARGET}" | tr "[:upper:]" "[:lower:]"`
+
+      if [ "${TEMPROOT_TYPE}" = "${SYMLINK_TARGET_TYPE}" ]; then
+        # if DESTDIR is set it must be a removable prefix of SYMLINK_TARGET
+        if [ -z "${DESTDIR}" ] || [ "${SYMLINK_TARGET}" != "${SYMLINK_TARGET##${DESTDIR}}" ]; then
+          case " ${ALLOW_SYMLINK} /boot " in
+            *" ${COMPFILE#.} "*) continue ;;
+          esac
+        fi
+      fi
+    fi
+
     echo "*** The installed file ${DESTDIR}${COMPFILE#.} has the type \"$INSTALLED_TYPE\""
     echo "    but the new version has the type \"$TEMPROOT_TYPE\""
     echo ''
@@ -1062,6 +1093,7 @@
 		esac ;;
     *)	echo ''
         echo "*** See the man page about adding ${COMPFILE#.} to the list of IGNORE_FILES"
+        echo "*** or ALLOW_SYMLINK"
         press_to_continue ;;
     esac
     echo ''