diff --git a/Documentation/Makefile b/Documentation/Makefile
index e853d89eb5..f0e5bc9c0c 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -282,11 +282,13 @@ ifneq ($(filter-out lint-docs clean,$(MAKECMDGOALS)),)
 -include ../GIT-VERSION-FILE
 endif
 
+mergetools_txt = mergetools-diff.txt mergetools-merge.txt
+
 #
 # Determine "include::" file references in asciidoc files.
 #
 docdep_prereqs = \
-	mergetools-list.made $(mergetools_txt) \
+	$(mergetools_txt) \
 	cmd-list.made $(cmds_txt)
 
 doc.dep : $(docdep_prereqs) $(DOC_DEP_TXT) build-docdep.perl
@@ -315,19 +317,11 @@ cmd-list.made: cmd-list.perl ../command-list.txt $(MAN1_TXT)
 	$(QUIET_GEN)$(PERL_PATH) ./cmd-list.perl .. . $(cmds_txt) && \
 	date >$@
 
-mergetools_txt = mergetools-diff.txt mergetools-merge.txt
-
-$(mergetools_txt): mergetools-list.made
-
-mergetools-list.made: ../git-mergetool--lib.sh $(wildcard ../mergetools/*)
-	$(QUIET_GEN) \
-	$(SHELL_PATH) -c 'MERGE_TOOLS_DIR=../mergetools && TOOL_MODE=diff && \
-		. ../git-mergetool--lib.sh && \
-		show_tool_names can_diff' | sed -e "s/\([a-z0-9]*\)/\`\1\`;;/" >mergetools-diff.txt && \
-	$(SHELL_PATH) -c 'MERGE_TOOLS_DIR=../mergetools && TOOL_MODE=merge && \
-		. ../git-mergetool--lib.sh && \
-		show_tool_names can_merge' | sed -e "s/\([a-z0-9]*\)/\`\1\`;;/" >mergetools-merge.txt && \
-	date >$@
+mergetools-%.txt: generate-mergetool-list.sh ../git-mergetool--lib.sh $(wildcard ../mergetools/*)
+mergetools-diff.txt:
+	$(QUIET_GEN)$(SHELL_PATH) ./generate-mergetool-list.sh .. diff $@
+mergetools-merge.txt:
+	$(QUIET_GEN)$(SHELL_PATH) ./generate-mergetool-list.sh .. merge $@
 
 TRACK_ASCIIDOCFLAGS = $(subst ','\'',$(ASCIIDOC_COMMON):$(ASCIIDOC_HTML):$(ASCIIDOC_DOCBOOK))
 
diff --git a/Documentation/generate-mergetool-list.sh b/Documentation/generate-mergetool-list.sh
new file mode 100755
index 0000000000..6700498b93
--- /dev/null
+++ b/Documentation/generate-mergetool-list.sh
@@ -0,0 +1,17 @@
+#!/bin/sh
+
+if test "$#" -ne 3
+then
+	echo >&2 "USAGE: $0 <SOURCE_DIR> <MODE> <OUTPUT>"
+	exit 1
+fi
+
+SOURCE_DIR="$1"
+TOOL_MODE="$2"
+OUTPUT="$3"
+MERGE_TOOLS_DIR="$SOURCE_DIR/mergetools"
+
+(
+	. "$SOURCE_DIR"/git-mergetool--lib.sh &&
+	show_tool_names can_$TOOL_MODE
+) | sed -e "s/\([a-z0-9]*\)/\`\1\`;;/" >"$OUTPUT"