diff --git a/core/config.mk b/core/config.mk
index 9d77fe5..59b8de0 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -569,6 +569,13 @@
 endif
 .KATI_READONLY := ALLOW_MISSING_DEPENDENCIES
 
+TARGET_BUILD_APPS_USE_PREBUILT_SDK :=
+ifdef TARGET_BUILD_APPS
+  ifndef UNBUNDLED_BUILD_SDKS_FROM_SOURCE
+    TARGET_BUILD_APPS_USE_PREBUILT_SDK := true
+  endif
+endif
+
 prebuilt_sdk_tools := prebuilts/sdk/tools
 prebuilt_sdk_tools_bin := $(prebuilt_sdk_tools)/$(HOST_OS)/bin
 
diff --git a/core/java.mk b/core/java.mk
index 932a421..e564db2 100644
--- a/core/java.mk
+++ b/core/java.mk
@@ -109,7 +109,7 @@
 
 aidl_preprocess_import :=
 ifdef LOCAL_SDK_VERSION
-ifneq ($(filter current system_current test_current core_current, $(LOCAL_SDK_VERSION)$(TARGET_BUILD_APPS)),)
+ifneq ($(filter current system_current test_current core_current, $(LOCAL_SDK_VERSION)$(TARGET_BUILD_APPS_USE_PREBUILT_SDK)),)
   # LOCAL_SDK_VERSION is current and no TARGET_BUILD_APPS
   aidl_preprocess_import := $(TARGET_OUT_COMMON_INTERMEDIATES)/framework.aidl
 else
diff --git a/core/java_common.mk b/core/java_common.mk
index f4c47c8..ac26e5e 100644
--- a/core/java_common.mk
+++ b/core/java_common.mk
@@ -29,7 +29,7 @@
     LOCAL_JAVA_LANGUAGE_VERSION := 1.7
   else ifneq (,$(filter $(LOCAL_SDK_VERSION), $(TARGET_SDK_VERSIONS_WITHOUT_JAVA_19_SUPPORT)))
     LOCAL_JAVA_LANGUAGE_VERSION := 1.8
-  else ifneq (,$(LOCAL_SDK_VERSION)$(TARGET_BUILD_APPS))
+  else ifneq (,$(LOCAL_SDK_VERSION)$(TARGET_BUILD_APPS_USE_PREBUILT_SDK))
     # TODO(ccross): allow 1.9 for current and unbundled once we have SDK system modules
     LOCAL_JAVA_LANGUAGE_VERSION := 1.8
   else
@@ -276,7 +276,7 @@
       my_system_modules := $(DEFAULT_SYSTEM_MODULES)
     endif  # LOCAL_NO_STANDARD_LIBRARIES
 
-    ifneq (,$(TARGET_BUILD_APPS))
+    ifneq (,$(TARGET_BUILD_APPS_USE_PREBUILT_SDK))
       sdk_libs := $(foreach lib_name,$(LOCAL_SDK_LIBRARIES),$(call resolve-prebuilt-sdk-module,system_current,$(lib_name)))
     else
       # When SDK libraries are referenced from modules built without SDK, provide the all APIs to them
@@ -291,7 +291,7 @@
              Choices are: $(TARGET_AVAILABLE_SDK_VERSIONS))
     endif
 
-    ifneq (,$(TARGET_BUILD_APPS)$(filter-out %current,$(LOCAL_SDK_VERSION)))
+    ifneq (,$(TARGET_BUILD_APPS_USE_PREBUILT_SDK)$(filter-out %current,$(LOCAL_SDK_VERSION)))
       # TARGET_BUILD_APPS mode or numbered SDK. Use prebuilt modules.
       sdk_module := $(call resolve-prebuilt-sdk-module,$(LOCAL_SDK_VERSION))
       sdk_libs := $(foreach lib_name,$(LOCAL_SDK_LIBRARIES),$(call resolve-prebuilt-sdk-module,$(LOCAL_SDK_VERSION),$(lib_name)))
@@ -333,7 +333,7 @@
   # related classes to be present. This change adds stubs needed for
   # javac to compile lambdas.
   ifneq ($(LOCAL_NO_STANDARD_LIBRARIES),true)
-    ifdef TARGET_BUILD_APPS
+    ifdef TARGET_BUILD_APPS_USE_PREBUILT_SDK
       full_java_bootclasspath_libs += $(call java-lib-header-files,sdk-core-lambda-stubs)
     else
       full_java_bootclasspath_libs += $(call java-lib-header-files,core-lambda-stubs)
diff --git a/core/package_internal.mk b/core/package_internal.mk
index 451fce7..a46d76a 100644
--- a/core/package_internal.mk
+++ b/core/package_internal.mk
@@ -496,7 +496,7 @@
 # resources.
 ifeq ($(LOCAL_SDK_RES_VERSION),core_current)
 # core_current doesn't contain any framework resources.
-else ifneq ($(filter-out current system_current test_current,$(LOCAL_SDK_RES_VERSION))$(if $(TARGET_BUILD_APPS),$(filter current system_current test_current,$(LOCAL_SDK_RES_VERSION))),)
+else ifneq ($(filter-out current system_current test_current,$(LOCAL_SDK_RES_VERSION))$(if $(TARGET_BUILD_APPS_USE_PREBUILT_SDK),$(filter current system_current test_current,$(LOCAL_SDK_RES_VERSION))),)
 # for released sdk versions, the platform resources were built into android.jar.
 framework_res_package_export := \
     $(call resolve-prebuilt-sdk-jar-path,$(LOCAL_SDK_RES_VERSION))
diff --git a/core/soong_config.mk b/core/soong_config.mk
index 3dc6d9a..85be1e7 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -36,6 +36,7 @@
 
 $(call add_json_bool, Allow_missing_dependencies,        $(ALLOW_MISSING_DEPENDENCIES))
 $(call add_json_bool, Unbundled_build,                   $(TARGET_BUILD_APPS))
+$(call add_json_bool, Unbundled_build_sdks_from_source,  $(UNBUNDLED_BUILD_SDKS_FROM_SOURCE))
 $(call add_json_bool, Pdk,                               $(filter true,$(TARGET_BUILD_PDK)))
 
 $(call add_json_bool, Debuggable,                        $(filter userdebug eng,$(TARGET_BUILD_VARIANT)))
diff --git a/core/static_java_library.mk b/core/static_java_library.mk
index 2a87705..cee7c9e 100644
--- a/core/static_java_library.mk
+++ b/core/static_java_library.mk
@@ -110,7 +110,7 @@
 framework_res_package_export :=
 # Please refer to package.mk
 ifneq ($(LOCAL_NO_STANDARD_LIBRARIES),true)
-ifneq ($(filter-out current system_current test_current,$(LOCAL_SDK_RES_VERSION))$(if $(TARGET_BUILD_APPS),$(filter current system_current test_current,$(LOCAL_SDK_RES_VERSION))),)
+ifneq ($(filter-out current system_current test_current,$(LOCAL_SDK_RES_VERSION))$(if $(TARGET_BUILD_APPS_USE_PREBUILT_SDK),$(filter current system_current test_current,$(LOCAL_SDK_RES_VERSION))),)
 framework_res_package_export := \
     $(call resolve-prebuilt-sdk-jar-path,$(LOCAL_SDK_RES_VERSION))
 else