diff --git a/Makefile b/Makefile
index 97ee0be24d52..d487fca342c4 100644
--- a/Makefile
+++ b/Makefile
@@ -483,10 +483,13 @@ PHONY += outputmakefile
 # outputmakefile generates a Makefile in the output directory, if using a
 # separate output directory. This allows convenient use of make in the
 # output directory.
+# At the same time when output Makefile generated, generate .gitignore to
+# ignore whole output directory
 outputmakefile:
 ifneq ($(KBUILD_SRC),)
 	$(Q)ln -fsn $(srctree) source
 	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile $(srctree)
+	$(Q){ echo "# this is build directory, ignore it"; echo "*"; } > .gitignore
 endif
 
 ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)