diff --git a/ForceProguard.mk b/ForceProguard.mk
new file mode 100755
index 0000000..e6f4fea
--- /dev/null
+++ b/ForceProguard.mk
@@ -0,0 +1,40 @@
+#  Copyright (C) 2015 The Android Open Source Project
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+# Check to see if we need to force proguard to re-run, typically after using tapas to
+# switch to/from eng builds. This is determined by comparing the flag files used in the previous
+# build. If the flag files have changed, proguard is rerun.
+
+# If the LOCAL_MODULE being setup isn't a build target, then don't run ForceProguard.
+ifneq (,$(findstring $(LOCAL_MODULE), $(TARGET_BUILD_APPS)))
+
+PREVIOUS_FLAG_FILES_USED_DIR := $(call local-intermediates-dir,1)
+
+# If the local intermediates dir doesn't exist, ForceProguard won't work.
+ifneq ($(wildcard $(PREVIOUS_FLAG_FILES_USED_DIR)),)
+PREVIOUS_FLAG_FILES_USED_FILE := $(PREVIOUS_FLAG_FILES_USED_DIR)/previous_proguard_flag_files
+PREVIOUS_FLAG_FILES_USED := $(if $(wildcard $(PREVIOUS_FLAG_FILES_USED_FILE)), \
+                                $(shell cat $(PREVIOUS_FLAG_FILES_USED_FILE)))
+
+ifneq ($(strip $(PREVIOUS_FLAG_FILES_USED)), $(strip $(LOCAL_PROGUARD_FLAG_FILES)))
+$(info *** Flag files used for proguard have changed; forcing proguard to rerun.)
+$(shell touch $(LOCAL_PATH)/proguard.flags)
+$(shell echo $(LOCAL_PROGUARD_FLAG_FILES) > $(PREVIOUS_FLAG_FILES_USED_FILE))
+endif
+
+endif
+# End local intermediates directory existence check
+
+endif
+# End LOCAL_MODULE is a build target check