diff --git a/core/build-system.html b/core/build-system.html
index e72e141..c7938cc 100644
--- a/core/build-system.html
+++ b/core/build-system.html
@@ -592,6 +592,17 @@
 </ul>
 </p>
 
+<h4>LOCAL_ANNOTATION_PROCESSORS</h4>
+<p>Set this to a list of modules built with <code>BUILD_HOST_JAVA_LIBRARY</code>
+to have their jars passed to javac with -processorpath for use as annotation
+processors.</p>
+
+<h4>LOCAL_ANNOTATION_PROCESSOR_CLASSES</h4>
+<p>Set this to a list of classes to be passed to javac as -processor arguments.
+This list is would be unnecessary, as javac will autodetect annotation processor
+classes, except that the Grok tool that is used on the Android source code
+does not autodetect them and requires listing them manually.</p>
+
 <h4>LOCAL_ASSET_FILES</h4>
 <p>In Android.mk files that <code>include $(BUILD_PACKAGE)</code> set this
 to the set of files you want built into your app.  Usually:</p>
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 3619106..a4751fd 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -12,6 +12,8 @@
 LOCAL_ADDITIONAL_JAVA_DIR:=
 LOCAL_AIDL_INCLUDES:=
 LOCAL_ALLOW_UNDEFINED_SYMBOLS:=
+LOCAL_ANNOTATION_PROCESSORS:=
+LOCAL_ANNOTATION_PROCESSOR_CLASSES:=
 LOCAL_APK_LIBRARIES:=
 LOCAL_ARM_MODE:=
 LOCAL_ASFLAGS:=
diff --git a/core/definitions.mk b/core/definitions.mk
index 94b0436..3e3bf72 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -2188,9 +2188,9 @@
 # $(2): bootclasspath
 define compile-java
 $(hide) rm -f $@
-$(hide) rm -rf $(PRIVATE_CLASS_INTERMEDIATES_DIR)
+$(hide) rm -rf $(PRIVATE_CLASS_INTERMEDIATES_DIR) $(PRIVATE_ANNO_INTERMEDIATES_DIR)
 $(hide) mkdir -p $(dir $@)
-$(hide) mkdir -p $(PRIVATE_CLASS_INTERMEDIATES_DIR)
+$(hide) mkdir -p $(PRIVATE_CLASS_INTERMEDIATES_DIR) $(PRIVATE_ANNO_INTERMEDIATES_DIR)
 $(call unzip-jar-files,$(PRIVATE_STATIC_JAVA_LIBRARIES),$(PRIVATE_CLASS_INTERMEDIATES_DIR))
 $(call dump-words-to-file,$(PRIVATE_JAVA_SOURCES),$(PRIVATE_CLASS_INTERMEDIATES_DIR)/java-source-list)
 $(hide) if [ -d "$(PRIVATE_SOURCE_INTERMEDIATES_DIR)" ]; then \
@@ -2209,7 +2209,7 @@
     $(addprefix -classpath ,$(strip \
         $(call normalize-path-list,$(PRIVATE_ALL_JAVA_LIBRARIES)))) \
     $(if $(findstring true,$(PRIVATE_WARNINGS_ENABLE)),$(xlint_unchecked),) \
-    -extdirs "" -d $(PRIVATE_CLASS_INTERMEDIATES_DIR) \
+    -extdirs "" -d $(PRIVATE_CLASS_INTERMEDIATES_DIR) -s $(PRIVATE_ANNO_INTERMEDIATES_DIR) \
     $(PRIVATE_JAVACFLAGS) \
     \@$(PRIVATE_CLASS_INTERMEDIATES_DIR)/java-source-list-uniq \
     || ( rm -rf $(PRIVATE_CLASS_INTERMEDIATES_DIR) ; exit 41 ) \
@@ -3334,4 +3334,4 @@
   $(eval include $(BUILD_SYSTEM)/generate_enforce_rro.mk) \
   $(eval ALL_MODULES.$(enforce_rro_source_module).REQUIRED += $(enforce_rro_module)) \
 )
-endef
\ No newline at end of file
+endef
diff --git a/core/host_dalvik_java_library.mk b/core/host_dalvik_java_library.mk
index 34e88ce..a7c1ad6 100644
--- a/core/host_dalvik_java_library.mk
+++ b/core/host_dalvik_java_library.mk
@@ -86,7 +86,7 @@
 ifndef LOCAL_JACK_ENABLED
 
 $(full_classes_compiled_jar): PRIVATE_JAVA_LAYERS_FILE := $(layers_file)
-$(full_classes_compiled_jar): PRIVATE_JAVACFLAGS := $(GLOBAL_JAVAC_DEBUG_FLAGS) $(LOCAL_JAVACFLAGS)
+$(full_classes_compiled_jar): PRIVATE_JAVACFLAGS := $(GLOBAL_JAVAC_DEBUG_FLAGS) $(LOCAL_JAVACFLAGS) $(annotation_processor_flags)
 $(full_classes_compiled_jar): PRIVATE_JAR_EXCLUDE_FILES :=
 $(full_classes_compiled_jar): PRIVATE_JAR_PACKAGES :=
 $(full_classes_compiled_jar): PRIVATE_JAR_EXCLUDE_PACKAGES :=
@@ -96,6 +96,7 @@
         $(full_java_lib_deps) \
         $(jar_manifest_file) \
         $(proto_java_sources_file_stamp) \
+        $(annotation_processor_deps) \
         $(LOCAL_ADDITIONAL_DEPENDENCIES)
 	$(transform-host-java-to-package)
 
diff --git a/core/host_java_library.mk b/core/host_java_library.mk
index f1da553..9f640b0 100644
--- a/core/host_java_library.mk
+++ b/core/host_java_library.mk
@@ -64,7 +64,7 @@
 endif
 
 $(full_classes_compiled_jar): PRIVATE_JAVA_LAYERS_FILE := $(layers_file)
-$(full_classes_compiled_jar): PRIVATE_JAVACFLAGS := $(GLOBAL_JAVAC_DEBUG_FLAGS) $(LOCAL_JAVACFLAGS)
+$(full_classes_compiled_jar): PRIVATE_JAVACFLAGS := $(GLOBAL_JAVAC_DEBUG_FLAGS) $(LOCAL_JAVACFLAGS) $(annotation_processor_flags)
 $(full_classes_compiled_jar): PRIVATE_JAR_EXCLUDE_FILES :=
 $(full_classes_compiled_jar): PRIVATE_JAR_PACKAGES :=
 $(full_classes_compiled_jar): PRIVATE_JAR_EXCLUDE_PACKAGES :=
@@ -74,6 +74,7 @@
         $(full_java_lib_deps) \
         $(jar_manifest_file) \
         $(proto_java_sources_file_stamp) \
+        $(annotation_processor_deps) \
         $(NORMALIZE_PATH) \
         $(LOCAL_ADDITIONAL_DEPENDENCIES)
 	$(transform-host-java-to-package)
diff --git a/core/java.mk b/core/java.mk
index f7f7eee..b9c48c6 100644
--- a/core/java.mk
+++ b/core/java.mk
@@ -424,7 +424,7 @@
 LOCAL_JAVACFLAGS += $(LOCAL_ERROR_PRONE_FLAGS)
 endif
 
-$(full_classes_compiled_jar): PRIVATE_JAVACFLAGS := $(GLOBAL_JAVAC_DEBUG_FLAGS) $(LOCAL_JAVACFLAGS)
+$(full_classes_compiled_jar): PRIVATE_JAVACFLAGS := $(GLOBAL_JAVAC_DEBUG_FLAGS) $(LOCAL_JAVACFLAGS) $(annotation_processor_flags)
 $(full_classes_compiled_jar): PRIVATE_JAR_EXCLUDE_FILES := $(LOCAL_JAR_EXCLUDE_FILES)
 $(full_classes_compiled_jar): PRIVATE_JAR_PACKAGES := $(LOCAL_JAR_PACKAGES)
 $(full_classes_compiled_jar): PRIVATE_JAR_EXCLUDE_PACKAGES := $(LOCAL_JAR_EXCLUDE_PACKAGES)
@@ -437,6 +437,7 @@
         $(layers_file) \
         $(RenderScript_file_stamp) \
         $(proto_java_sources_file_stamp) \
+        $(annotation_processor_deps) \
         $(NORMALIZE_PATH) \
         $(LOCAL_ADDITIONAL_DEPENDENCIES)
 	$(transform-java-to-classes.jar)
@@ -730,13 +731,14 @@
 $(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_JACK_PROGUARD_FLAGS :=
 endif # LOCAL_PROGUARD_ENABLED defined
 
-$(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_JACK_FLAGS := $(GLOBAL_JAVAC_DEBUG_FLAGS) $(LOCAL_JACK_FLAGS)
+$(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_JACK_FLAGS := $(GLOBAL_JAVAC_DEBUG_FLAGS) $(LOCAL_JACK_FLAGS) $(annotation_processor_flags)
 $(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_JACK_VERSION := $(LOCAL_JACK_VERSION)
 
 jack_all_deps := $(java_sources) $(java_resource_sources) $(full_jack_deps) \
         $(jar_manifest_file) $(layers_file) $(RenderScript_file_stamp) \
         $(common_proguard_flag_files) $(proguard_flag_files) \
-        $(proto_java_sources_file_stamp) $(LOCAL_ADDITIONAL_DEPENDENCIES) $(LOCAL_JARJAR_RULES) \
+        $(proto_java_sources_file_stamp) $(annotation_processor_deps) \
+        $(LOCAL_ADDITIONAL_DEPENDENCIES) $(LOCAL_JARJAR_RULES) \
         $(NORMALIZE_PATH) $(JACK_DEFAULT_ARGS) $(JACK)
 
 $(jack_check_timestamp): $(jack_all_deps) | setup-jack-server
diff --git a/core/java_common.mk b/core/java_common.mk
index 67943a4..600208a 100644
--- a/core/java_common.mk
+++ b/core/java_common.mk
@@ -148,6 +148,20 @@
 need_compile_java := $(strip $(all_java_sources)$(all_res_assets)$(java_resource_sources))$(LOCAL_STATIC_JAVA_LIBRARIES)$(filter true,$(LOCAL_SOURCE_FILES_ALL_GENERATED))
 ifdef need_compile_java
 
+annotation_processor_flags :=
+annotation_processor_deps :=
+
+ifdef LOCAL_ANNOTATION_PROCESSORS
+  annotation_processor_jars := $(call java-lib-deps,$(LOCAL_ANNOTATION_PROCESSORS),true)
+  annotation_processor_flags += -processorpath $(call normalize-path-list,$(annotation_processor_jars))
+  annotation_processor_deps += $(annotation_processor_jars)
+
+  # b/25860419: annotation processors must be explicitly specified for grok
+  annotation_processor_flags += $(foreach class,$(LOCAL_ANNOTATION_PROCESSOR_CLASSES),-processor $(class))
+
+  annotation_processor_jars :=
+endif
+
 full_static_java_libs := \
     $(foreach lib,$(LOCAL_STATIC_JAVA_LIBRARIES), \
       $(call intermediates-dir-for, \
@@ -159,6 +173,7 @@
 $(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_ASSET_DIR := $(LOCAL_ASSET_DIR)
 
 $(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_CLASS_INTERMEDIATES_DIR := $(intermediates.COMMON)/classes
+$(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_ANNO_INTERMEDIATES_DIR := $(intermediates.COMMON)/anno
 $(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_SOURCE_INTERMEDIATES_DIR := $(intermediates.COMMON)/src
 $(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_HAS_PROTO_SOURCES := $(if $(proto_sources),true)
 $(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_PROTO_SOURCE_INTERMEDIATES_DIR := $(intermediates.COMMON)/proto