diff --git a/sys/indent.sh b/sys/indent.sh
index 507278e66b..7c087a28e9 100755
--- a/sys/indent.sh
+++ b/sys/indent.sh
@@ -1,6 +1,53 @@
 #!/bin/sh
-D="$(dirname "$PWD/$0")"
-#shellcheck disable=SC2048
-#shellcheck disable=SC2086
-uncrustify -c ${D}/uncrustify.cfg $*
-diff -ru "$1" "$1.uncrustify"
+
+IFILE="$1"
+
+if [ -z "${IFILE}" ]; then
+	echo "Usage: indent.sh [-i|-u] [file]"
+	echo " -i - indent in place (modify file"
+	echo " -u - indent in place (modify file"
+	exit 1
+fi
+
+CWD="$PWD"
+INPLACE=0
+UNIFIED=0
+
+if [ "${IFILE}" = "-i" ]; then
+	shift
+	INPLACE=1
+	IFILE="$1"
+fi
+
+if [ "${IFILE}" = "-u" ]; then
+	shift
+	UNIFIED=1
+	IFILE="$1"
+fi
+
+while : ; do
+	[ "$PWD" = / ] && break
+	if [ -f doc/clang-format ]; then
+		cp -f doc/clang-format ${CWD}/.clang-format
+		(
+		cd "$CWD"
+		clang-format "${IFILE}"  > .tmp-format
+		# fix ternary conditional indent
+		cat .tmp-format | sed -e 's, \? ,? ,g' > .tmp-format2
+		# do not space before parenthesis on function signatures
+		awk '{if (/^static/ || /^R_API/) { gsub(/ \(/,"("); }; print;}' \
+			< .tmp-format2 > .tmp-format
+		if [ "$UNIFIED" = 1 ]; then
+			diff -ru "${IFILE}" .tmp-format
+			rm .tmp-format
+		elif [ "$INPLACE" = 1 ]; then
+			mv .tmp-format $a
+		else
+			cat .tmp-format
+			rm .tmp-format
+		fi
+		)
+		rm -f ${CWD}/.clang-format
+	fi
+	cd ..
+done