diff --git a/core/main.mk b/core/main.mk
index ffff1f7..1931ea9 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -93,6 +93,10 @@
 # and host information.
 include $(BUILD_SYSTEM)/config.mk
 
+ifeq ($(USE_NINJA),true)
+include build/core/ninja.mk
+else # !USE_NINJA
+
 # Write the build number to a file so it can be read back in
 # without changing the command line every time.  Avoids rebuilds
 # when using ninja.
@@ -1065,3 +1069,4 @@
 .PHONY: nothing
 nothing:
 	@echo Successfully read the makefiles.
+endif # !USE_NINJA
diff --git a/core/ninja.mk b/core/ninja.mk
new file mode 100644
index 0000000..05498d8
--- /dev/null
+++ b/core/ninja.mk
@@ -0,0 +1,50 @@
+KATI ?= $(HOST_OUT_EXECUTABLES)/ckati
+
+KATI_OUTPUTS := $(PRODUCT_OUT)/build.ninja $(PRODUCT_OUT)/ninja.sh
+NINJA_GOALS := fastincremental generateonly droid showcommands
+
+ANDROID_TARGETS := $(filter-out $(KATI_OUTPUTS) $(NINJA_GOALS),$(MAKECMDGOALS))
+
+ifeq (,$(NINJA_STATUS))
+NINJA_STATUS := [%p %s/%t]$(space)
+endif
+
+ifneq (,$(filter showcommands,$(MAKECMDGOALS)))
+NINJA_ARGS += "-v"
+PHONY: showcommands
+showcommands: droid
+endif
+
+ifeq (,$(filter generateonly,$(MAKECMDGOALS)))
+fastincremental droid $(ANDROID_TARGETS): ninja.intermediate
+	@#empty
+
+.INTERMEDIATE: ninja.intermediate
+ninja.intermediate: $(KATI_OUTPUTS)
+	@echo Starting build with ninja
+	@PATH=prebuilts/ninja/$(HOST_PREBUILT_TAG)/:$$PATH NINJA_STATUS="$(NINJA_STATUS)" $(PRODUCT_OUT)/ninja.sh -C $(TOP) $(NINJA_ARGS) $(ANDROID_TARGETS)
+else
+generateonly droid $(ANDROID_TARGETS): $(KATI_OUTPUTS)
+	@#empty
+endif
+
+ifeq (,$(filter fastincremental,$(MAKECMDGOALS)))
+KATI_FORCE := FORCE
+endif
+
+$(KATI_OUTPUTS): kati.intermediate $(KATI_FORCE)
+
+.INTERMEDIATE: kati.intermediate
+kati.intermediate: $(KATI)
+	@echo Running kati to generate build.ninja...
+	@#TODO: use separate ninja file for mm or single target build
+	@$(KATI) --ninja --ninja_dir=$(PRODUCT_OUT) --ignore_optional_include=out/%.P --detect_android_echo --use_find_emulator -f build/core/main.mk $(ANDROID_TARGETS) USE_NINJA=false
+
+KATI_CXX := $(CLANG_CXX) $(CLANG_HOST_GLOBAL_CPPFLAGS)
+KATI_LD := $(CLANG_CXX) $(CLANG_HOST_GLOBAL_LDFLAGS)
+KATI_INTERMEDIATES_PATH := $(HOST_OUT_INTERMEDIATES)/EXECUTABLES/ckati_intermediates
+KATI_BIN_PATH := $(HOST_OUT_EXECUTABLES)
+include build/kati/Makefile.ckati
+
+.PHONY: FORCE
+FORCE: