diff --git a/Changes.md b/Changes.md
index 1fadcefdca..be2a271e70 100644
--- a/Changes.md
+++ b/Changes.md
@@ -1,5 +1,9 @@
 # Build System Changes for Android.mk Writers
 
+## Deprecation of `BUILD_*` module types
+
+See [build/make/Deprecation.md](Deprecation.md) for the current status.
+
 ## `PRODUCT_HOST_PACKAGES` split from `PRODUCT_PACKAGES` {#PRODUCT_HOST_PACKAGES}
 
 Previously, adding a module to `PRODUCT_PACKAGES` that supported both the host
diff --git a/Deprecation.md b/Deprecation.md
new file mode 100644
index 0000000000..6468f464f3
--- /dev/null
+++ b/Deprecation.md
@@ -0,0 +1,56 @@
+# Deprecation of Make
+
+We've made significant progress converting AOSP from Make to Soong (Android.mk
+to Android.bp), and we're ready to start turning off pieces of Make. If you
+have any problems converting, please contact us via:
+
+* The [android-building@googlegroups.com] group.
+* Our [public bug tracker](https://issuetracker.google.com/issues/new?component=381517).
+* Or privately through your existing contacts at Google.
+
+## Status
+
+[build/make/core/deprecation.mk] is the source of truth, but for easy browsing:
+
+| Module type                | State     |
+| -------------------------- | --------- |
+| `BUILD_HOST_TEST_CONFIG`   | Warning   |
+| `BUILD_TARGET_TEST_CONFIG` | Warning   |
+| `BUILD_*`                  | Available |
+
+## Module Type Deprecation Process
+
+We'll be turning off `BUILD_*` module types as all of the users are removed
+from AOSP (and Google's internal trees). The process will go something like
+this, using `BUILD_PACKAGE` as an example:
+
+* Prerequisite: all common users of `BUILD_PACKAGE` have been removed (some
+  device-specific ones may remain).
+* `BUILD_PACKAGE` will be moved from `AVAILABLE_BUILD_MODULE_TYPES` to
+  `DEFAULT_WARNING_BUILD_MODULE_TYPES` in [build/make/core/deprecation.mk]. This
+  will make referring to `BUILD_PACKAGE` a warning.
+* Any devices that still have warnings will have
+  `BUILD_BROKEN_USES_BUILD_PACKAGE := true` added to their `BoardConfig.mk`.
+* `BUILD_PACKAGE` will be switched from `DEFAULT_WARNING_BUILD_MODULE_TYPES` to
+  `DEFAULT_ERROR_BUILD_MODULE_TYPES`, which will turn referring to
+  `BUILD_PACKAGE` into an error unless the device has overridden it.
+* At some later point, after all devices in AOSP no longer set
+  `BUILD_BROKEN_USES_BUILD_PACKAGE`, `BUILD_PACKAGE` will be moved from
+  `DEFAULT_ERROR_BUILD_MODULE_TYPES` to `OBSOLETE_BUILD_MODULE_TYPES` and the
+  code will be removed. It will no longer be possible to use `BUILD_PACKAGE`.
+
+In most cases, we expect module types to stay in the default warning state for
+about two weeks before becoming an error by default. Then it will spend some
+amount of time in the default error state before moving to obsolete -- we'll
+try and keep that around for a while, but other development may cause those to
+break, and the fix may to be to obsolete them. There is no expectation that the
+`BUILD_BROKEN_USES_BUILD_*` workarounds will work in a future release, it's a
+short-term workaround.
+
+Just to be clear, the above process will happen on the AOSP master branch. So
+if you're following Android releases, none of the deprecation steps will be in
+Android Q, and the 2020 release will have jumped directly to the end for many
+module types.
+
+[android-building@googlegroups.com]: https://groups.google.com/forum/#!forum/android-building
+[build/make/core/deprecation.mk]: /core/deprecation.mk
diff --git a/core/board_config.mk b/core/board_config.mk
index d32e30134d..e4b88cb601 100644
--- a/core/board_config.mk
+++ b/core/board_config.mk
@@ -92,6 +92,12 @@ _build_broken_var_list := \
   BUILD_BROKEN_ENG_DEBUG_TAGS \
   BUILD_BROKEN_USES_NETWORK \
 
+_build_broken_var_list += \
+  $(foreach m,$(AVAILABLE_BUILD_MODULE_TYPES) \
+              $(DEFAULT_WARNING_BUILD_MODULE_TYPES) \
+              $(DEFAULT_ERROR_BUILD_MODULE_TYPES), \
+    BUILD_BROKEN_USES_$(m))
+
 _board_true_false_vars := $(_build_broken_var_list)
 _board_strip_readonly_list += $(_build_broken_var_list)
 
@@ -511,3 +517,16 @@ ifneq (,$(_unsupported_systemsdk_versions))
   $(error System SDK versions '$(_unsupported_systemsdk_versions)' in BOARD_SYSTEMSDK_VERSIONS are not supported.\
           Supported versions are $(PLATFORM_SYSTEMSDK_VERSIONS))
 endif
+
+###########################################
+# Handle BUILD_BROKEN_USES_BUILD_*
+
+$(foreach m,$(DEFAULT_WARNING_BUILD_MODULE_TYPES),\
+  $(if $(filter false,$(BUILD_BROKEN_USES_$(m))),\
+    $(KATI_obsolete_var $(m),Please convert to Soong),\
+    $(KATI_deprecated_var $(m),Please convert to Soong)))
+
+$(foreach m,$(DEFAULT_ERROR_BUILD_MODULE_TYPES),\
+  $(if $(filter true,$(BUILD_BROKEN_USES_$(m))),\
+    $(KATI_deprecated_var $(m),Please convert to Soong),\
+    $(KATI_obsolete_var $(m),Please convert to Soong)))
diff --git a/core/config.mk b/core/config.mk
index b5fe8661de..16cd37625f 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -135,45 +135,48 @@ include $(BUILD_SYSTEM)/project_definitions.mk
 # Build system internal files
 # ###############################################################
 
-BUILD_COMBOS:= $(BUILD_SYSTEM)/combo
+BUILD_COMBOS :=$= $(BUILD_SYSTEM)/combo
 
-CLEAR_VARS:= $(BUILD_SYSTEM)/clear_vars.mk
-BUILD_HOST_STATIC_LIBRARY:= $(BUILD_SYSTEM)/host_static_library.mk
-BUILD_HOST_SHARED_LIBRARY:= $(BUILD_SYSTEM)/host_shared_library.mk
-BUILD_STATIC_LIBRARY:= $(BUILD_SYSTEM)/static_library.mk
-BUILD_HEADER_LIBRARY:= $(BUILD_SYSTEM)/header_library.mk
-BUILD_AUX_STATIC_LIBRARY:= $(BUILD_SYSTEM)/aux_static_library.mk
-BUILD_AUX_EXECUTABLE:= $(BUILD_SYSTEM)/aux_executable.mk
-BUILD_SHARED_LIBRARY:= $(BUILD_SYSTEM)/shared_library.mk
-BUILD_EXECUTABLE:= $(BUILD_SYSTEM)/executable.mk
-BUILD_HOST_EXECUTABLE:= $(BUILD_SYSTEM)/host_executable.mk
-BUILD_PACKAGE:= $(BUILD_SYSTEM)/package.mk
-BUILD_PHONY_PACKAGE:= $(BUILD_SYSTEM)/phony_package.mk
-BUILD_RRO_PACKAGE:= $(BUILD_SYSTEM)/build_rro_package.mk
-BUILD_HOST_PREBUILT:= $(BUILD_SYSTEM)/host_prebuilt.mk
-BUILD_PREBUILT:= $(BUILD_SYSTEM)/prebuilt.mk
-BUILD_MULTI_PREBUILT:= $(BUILD_SYSTEM)/multi_prebuilt.mk
-BUILD_JAVA_LIBRARY:= $(BUILD_SYSTEM)/java_library.mk
-BUILD_STATIC_JAVA_LIBRARY:= $(BUILD_SYSTEM)/static_java_library.mk
-BUILD_HOST_JAVA_LIBRARY:= $(BUILD_SYSTEM)/host_java_library.mk
-BUILD_COPY_HEADERS := $(BUILD_SYSTEM)/copy_headers.mk
-BUILD_NATIVE_TEST := $(BUILD_SYSTEM)/native_test.mk
-BUILD_NATIVE_BENCHMARK := $(BUILD_SYSTEM)/native_benchmark.mk
-BUILD_HOST_NATIVE_TEST := $(BUILD_SYSTEM)/host_native_test.mk
-BUILD_FUZZ_TEST := $(BUILD_SYSTEM)/fuzz_test.mk
-BUILD_HOST_FUZZ_TEST := $(BUILD_SYSTEM)/host_fuzz_test.mk
+CLEAR_VARS :=$= $(BUILD_SYSTEM)/clear_vars.mk
 
-BUILD_SHARED_TEST_LIBRARY := $(BUILD_SYSTEM)/shared_test_lib.mk
-BUILD_HOST_SHARED_TEST_LIBRARY := $(BUILD_SYSTEM)/host_shared_test_lib.mk
-BUILD_STATIC_TEST_LIBRARY := $(BUILD_SYSTEM)/static_test_lib.mk
-BUILD_HOST_STATIC_TEST_LIBRARY := $(BUILD_SYSTEM)/host_static_test_lib.mk
+BUILD_HOST_STATIC_LIBRARY :=$= $(BUILD_SYSTEM)/host_static_library.mk
+BUILD_HOST_SHARED_LIBRARY :=$= $(BUILD_SYSTEM)/host_shared_library.mk
+BUILD_STATIC_LIBRARY :=$= $(BUILD_SYSTEM)/static_library.mk
+BUILD_HEADER_LIBRARY :=$= $(BUILD_SYSTEM)/header_library.mk
+BUILD_AUX_STATIC_LIBRARY :=$= $(BUILD_SYSTEM)/aux_static_library.mk
+BUILD_AUX_EXECUTABLE :=$= $(BUILD_SYSTEM)/aux_executable.mk
+BUILD_SHARED_LIBRARY :=$= $(BUILD_SYSTEM)/shared_library.mk
+BUILD_EXECUTABLE :=$= $(BUILD_SYSTEM)/executable.mk
+BUILD_HOST_EXECUTABLE :=$= $(BUILD_SYSTEM)/host_executable.mk
+BUILD_PACKAGE :=$= $(BUILD_SYSTEM)/package.mk
+BUILD_PHONY_PACKAGE :=$= $(BUILD_SYSTEM)/phony_package.mk
+BUILD_RRO_PACKAGE :=$= $(BUILD_SYSTEM)/build_rro_package.mk
+BUILD_HOST_PREBUILT :=$= $(BUILD_SYSTEM)/host_prebuilt.mk
+BUILD_PREBUILT :=$= $(BUILD_SYSTEM)/prebuilt.mk
+BUILD_MULTI_PREBUILT :=$= $(BUILD_SYSTEM)/multi_prebuilt.mk
+BUILD_JAVA_LIBRARY :=$= $(BUILD_SYSTEM)/java_library.mk
+BUILD_STATIC_JAVA_LIBRARY :=$= $(BUILD_SYSTEM)/static_java_library.mk
+BUILD_HOST_JAVA_LIBRARY :=$= $(BUILD_SYSTEM)/host_java_library.mk
+BUILD_COPY_HEADERS :=$= $(BUILD_SYSTEM)/copy_headers.mk
+BUILD_NATIVE_TEST :=$= $(BUILD_SYSTEM)/native_test.mk
+BUILD_NATIVE_BENCHMARK :=$= $(BUILD_SYSTEM)/native_benchmark.mk
+BUILD_HOST_NATIVE_TEST :=$= $(BUILD_SYSTEM)/host_native_test.mk
+BUILD_FUZZ_TEST :=$= $(BUILD_SYSTEM)/fuzz_test.mk
+BUILD_HOST_FUZZ_TEST :=$= $(BUILD_SYSTEM)/host_fuzz_test.mk
 
-BUILD_NOTICE_FILE := $(BUILD_SYSTEM)/notice_files.mk
-BUILD_HOST_DALVIK_JAVA_LIBRARY := $(BUILD_SYSTEM)/host_dalvik_java_library.mk
-BUILD_HOST_DALVIK_STATIC_JAVA_LIBRARY := $(BUILD_SYSTEM)/host_dalvik_static_java_library.mk
+BUILD_SHARED_TEST_LIBRARY :=$= $(BUILD_SYSTEM)/shared_test_lib.mk
+BUILD_HOST_SHARED_TEST_LIBRARY :=$= $(BUILD_SYSTEM)/host_shared_test_lib.mk
+BUILD_STATIC_TEST_LIBRARY :=$= $(BUILD_SYSTEM)/static_test_lib.mk
+BUILD_HOST_STATIC_TEST_LIBRARY :=$= $(BUILD_SYSTEM)/host_static_test_lib.mk
 
-BUILD_HOST_TEST_CONFIG := $(BUILD_SYSTEM)/host_test_config.mk
-BUILD_TARGET_TEST_CONFIG := $(BUILD_SYSTEM)/target_test_config.mk
+BUILD_NOTICE_FILE :=$= $(BUILD_SYSTEM)/notice_files.mk
+BUILD_HOST_DALVIK_JAVA_LIBRARY :=$= $(BUILD_SYSTEM)/host_dalvik_java_library.mk
+BUILD_HOST_DALVIK_STATIC_JAVA_LIBRARY :=$= $(BUILD_SYSTEM)/host_dalvik_static_java_library.mk
+
+BUILD_HOST_TEST_CONFIG :=$= $(BUILD_SYSTEM)/host_test_config.mk
+BUILD_TARGET_TEST_CONFIG :=$= $(BUILD_SYSTEM)/target_test_config.mk
+
+include $(BUILD_SYSTEM)/deprecation.mk
 
 # ###############################################################
 # Parse out any modifier targets.
diff --git a/core/deprecation.mk b/core/deprecation.mk
new file mode 100644
index 0000000000..cbc938ac34
--- /dev/null
+++ b/core/deprecation.mk
@@ -0,0 +1,55 @@
+# These module types can still be used without warnings or errors.
+AVAILABLE_BUILD_MODULE_TYPES :=$= \
+  BUILD_AUX_EXECUTABLE \
+  BUILD_AUX_STATIC_LIBRARY \
+  BUILD_COPY_HEADERS \
+  BUILD_EXECUTABLE \
+  BUILD_FUZZ_TEST \
+  BUILD_HEADER_LIBRARY \
+  BUILD_HOST_DALVIK_JAVA_LIBRARY \
+  BUILD_HOST_DALVIK_STATIC_JAVA_LIBRARY \
+  BUILD_HOST_EXECUTABLE \
+  BUILD_HOST_FUZZ_TEST \
+  BUILD_HOST_JAVA_LIBRARY \
+  BUILD_HOST_NATIVE_TEST \
+  BUILD_HOST_PREBUILT \
+  BUILD_HOST_SHARED_LIBRARY \
+  BUILD_HOST_SHARED_TEST_LIBRARY \
+  BUILD_HOST_STATIC_LIBRARY \
+  BUILD_HOST_STATIC_TEST_LIBRARY \
+  BUILD_JAVA_LIBRARY \
+  BUILD_MULTI_PREBUILT \
+  BUILD_NATIVE_BENCHMARK \
+  BUILD_NATIVE_TEST \
+  BUILD_NOTICE_FILE \
+  BUILD_PACKAGE \
+  BUILD_PHONY_PACKAGE \
+  BUILD_PREBUILT \
+  BUILD_RRO_PACKAGE \
+  BUILD_SHARED_LIBRARY \
+  BUILD_SHARED_TEST_LIBRARY \
+  BUILD_STATIC_JAVA_LIBRARY \
+  BUILD_STATIC_LIBRARY \
+  BUILD_STATIC_TEST_LIBRARY \
+
+# These are BUILD_* variables that will throw a warning when used. This is
+# generally a temporary state until all the devices are marked with the
+# relevant BUILD_BROKEN_USES_BUILD_* variables, then these would move to
+# DEFAULT_ERROR_BUILD_MODULE_TYPES.
+DEFAULT_WARNING_BUILD_MODULE_TYPES :=$= \
+  BUILD_HOST_TEST_CONFIG \
+  BUILD_TARGET_TEST_CONFIG \
+
+# These are BUILD_* variables that are errors to reference, but you can set
+# BUILD_BROKEN_USES_BUILD_* in your BoardConfig.mk in order to turn them back
+# to warnings.
+DEFAULT_ERROR_BUILD_MODULE_TYPES :=$= \
+
+# These are BUILD_* variables that are always errors to reference.
+# Setting the BUILD_BROKEN_USES_BUILD_* variables is also an error.
+OBSOLETE_BUILD_MODULE_TYPES :=$= \
+
+$(foreach m,$(OBSOLETE_BUILD_MODULE_TYPES),\
+  $(KATI_obsolete_var $(m),Please convert to Soong) \
+  $(KATI_obsolete_var BUILD_BROKEN_USES_$(m),Please convert to Soong))
+