diff --git a/core/Makefile b/core/Makefile
index 40e9274..0cd3cdc 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1027,6 +1027,9 @@
     $(eval vendor_ramdisk_fragment_target := $(call build-vendor-ramdisk-fragment,$(vendor_ramdisk_fragment))) \
     $(if $(filter --ramdisk_type,$(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS)),, \
       $(eval BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS += --ramdisk_type DLKM))) \
+  $(if $(filter --ramdisk_name,$(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS)), \
+    $(error Must not specify --ramdisk_name for vendor ramdisk fragment: $(vendor_ramdisk_fragment))) \
+  $(eval BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS += --ramdisk_name $(vendor_ramdisk_fragment)) \
   $(eval INTERNAL_VENDOR_RAMDISK_FRAGMENT_TARGETS += $(vendor_ramdisk_fragment_target)) \
   $(eval INTERNAL_VENDOR_RAMDISK_FRAGMENT_ARGS += $(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS) --vendor_ramdisk_fragment $(vendor_ramdisk_fragment_target)) \
 )
@@ -2329,6 +2332,10 @@
 $(INSTALLED_VENDOR_DEBUG_RAMDISK_TARGET): DEBUG_RAMDISK_FILES := $(INTERNAL_DEBUG_RAMDISK_FILES)
 $(INSTALLED_VENDOR_DEBUG_RAMDISK_TARGET): VENDOR_RAMDISK_DIR := $(TARGET_VENDOR_RAMDISK_OUT)
 
+ifeq (true,$(BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT))
+$(INSTALLED_VENDOR_DEBUG_RAMDISK_TARGET): PRIVATE_ADDITIONAL_DIR := $(TARGET_RECOVERY_ROOT_OUT)
+endif
+
 INTERNAL_VENDOR_DEBUG_RAMDISK_FILES := $(filter $(TARGET_VENDOR_DEBUG_RAMDISK_OUT)/%, \
     $(ALL_GENERATED_SOURCES) \
     $(ALL_DEFAULT_INSTALLED_MODULES))
@@ -2345,8 +2352,7 @@
 	touch $(TARGET_VENDOR_DEBUG_RAMDISK_OUT)/force_debuggable
 	$(foreach debug_file,$(DEBUG_RAMDISK_FILES), \
 	  cp -f $(debug_file) $(subst $(PRODUCT_OUT)/debug_ramdisk,$(PRODUCT_OUT)/vendor_debug_ramdisk,$(debug_file)) &&) true
-	rsync -a $(VENDOR_RAMDISK_DIR)/ $(VENDOR_DEBUG_RAMDISK_DIR)
-	$(MKBOOTFS) -d $(TARGET_OUT) $(VENDOR_DEBUG_RAMDISK_DIR) | $(COMPRESSION_COMMAND) > $@
+	$(MKBOOTFS) -d $(TARGET_OUT) $(VENDOR_RAMDISK_DIR) $(VENDOR_DEBUG_RAMDISK_DIR) $(PRIVATE_ADDITIONAL_DIR) | $(COMPRESSION_COMMAND) > $@
 
 INSTALLED_FILES_FILE_VENDOR_DEBUG_RAMDISK := $(PRODUCT_OUT)/installed-files-vendor-ramdisk-debug.txt
 INSTALLED_FILES_JSON_VENDOR_DEBUG_RAMDISK := $(INSTALLED_FILES_FILE_VENDOR_DEBUG_RAMDISK:.txt=.json)
diff --git a/core/config.mk b/core/config.mk
index 9c04fe0..ed6429a 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -990,6 +990,13 @@
 
 endif # PRODUCT_USE_DYNAMIC_PARTITIONS
 
+# By default, we build the hidden API csv files from source. You can use
+# prebuilt hiddenapi files by setting BOARD_PREBUILT_HIDDENAPI_DIR to the name
+# of a directory containing both prebuilt hiddenapi-flags.csv and
+# hiddenapi-index.csv.
+BOARD_PREBUILT_HIDDENAPI_DIR ?=
+.KATI_READONLY := BOARD_PREBUILT_HIDDENAPI_DIR
+
 # ###############################################################
 # Set up final options.
 # ###############################################################
diff --git a/core/cxx_stl_setup.mk b/core/cxx_stl_setup.mk
index a2abb1a..f71ef72 100644
--- a/core/cxx_stl_setup.mk
+++ b/core/cxx_stl_setup.mk
@@ -78,18 +78,12 @@
         my_static_libraries += libc++demangle
 
         ifeq ($(my_link_type),static)
-            my_static_libraries += libm libc
-            ifeq (arm,$($(my_prefix)$(LOCAL_2ND_ARCH_VAR_PREFIX)ARCH))
-                my_static_libraries += libunwind_llvm
-                my_ldflags += -Wl,--exclude-libs,libunwind_llvm.a
-            else
-                my_static_libraries += libgcc_stripped
-                my_ldflags += -Wl,--exclude-libs,libgcc_stripped.a
-            endif
+            my_static_libraries += libm libc libunwind
         endif
     endif
 else ifeq ($(my_cxx_stl),ndk)
     # Using an NDK STL. Handled in binary.mk, except for the unwinder.
+    # TODO: Switch the NDK over to the LLVM unwinder for non-arm32 architectures.
     ifeq (arm,$($(my_prefix)$(LOCAL_2ND_ARCH_VAR_PREFIX)ARCH))
         my_static_libraries += libunwind_llvm
         my_ldflags += -Wl,--exclude-libs,libunwind_llvm.a
diff --git a/core/dex_preopt_config.mk b/core/dex_preopt_config.mk
index 6ef89da..06e2fb7 100644
--- a/core/dex_preopt_config.mk
+++ b/core/dex_preopt_config.mk
@@ -1,11 +1,19 @@
 DEX_PREOPT_CONFIG := $(SOONG_OUT_DIR)/dexpreopt.config
 
 ENABLE_PREOPT := true
+ENABLE_PREOPT_BOOT_IMAGES := true
 ifneq (true,$(filter true,$(WITH_DEXPREOPT)))
+  # Disable dexpreopt for libraries/apps and for boot images.
   ENABLE_PREOPT :=
+  ENABLE_PREOPT_BOOT_IMAGES :=
 else ifneq (true,$(filter true,$(PRODUCT_USES_DEFAULT_ART_CONFIG)))
+  # Disable dexpreopt for libraries/apps and for boot images: not having default
+  # ART config means that some important system properties are not set, which
+  # would result in passing bad arguments to dex2oat and failing the build.
   ENABLE_PREOPT :=
+  ENABLE_PREOPT_BOOT_IMAGES :=
 else ifeq (true,$(DISABLE_PREOPT))
+  # Disable dexpreopt for libraries/apps, but do compile boot images.
   ENABLE_PREOPT :=
 endif
 
@@ -65,6 +73,7 @@
   $(call json_start)
 
   $(call add_json_bool, DisablePreopt,                           $(call invert_bool,$(ENABLE_PREOPT)))
+  $(call add_json_bool, DisablePreoptBootImages,                 $(call invert_bool,$(ENABLE_PREOPT_BOOT_IMAGES)))
   $(call add_json_list, DisablePreoptModules,                    $(DEXPREOPT_DISABLED_MODULES))
   $(call add_json_bool, OnlyPreoptBootImageAndSystemServer,      $(filter true,$(WITH_DEXPREOPT_BOOT_IMG_AND_SYSTEM_SERVER_ONLY)))
   $(call add_json_bool, UseArtImage,                             $(filter true,$(DEXPREOPT_USE_ART_IMAGE)))
diff --git a/core/soong_config.mk b/core/soong_config.mk
index 5ca1d10..fde5832 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -147,6 +147,12 @@
 $(call add_json_bool, VndkUseCoreVariant,                $(TARGET_VNDK_USE_CORE_VARIANT))
 $(call add_json_bool, VndkSnapshotBuildArtifacts,        $(VNDK_SNAPSHOT_BUILD_ARTIFACTS))
 
+$(call add_json_bool, DirectedVendorSnapshot,            $(DIRECTED_VENDOR_SNAPSHOT))
+$(call add_json_map,  VendorSnapshotModules)
+$(foreach module,$(VENDOR_SNAPSHOT_MODULES),\
+  $(call add_json_bool,$(module),true))
+$(call end_json_map)
+
 $(call add_json_bool, Treble_linker_namespaces,          $(filter true,$(PRODUCT_TREBLE_LINKER_NAMESPACES)))
 $(call add_json_bool, Enforce_vintf_manifest,            $(filter true,$(PRODUCT_ENFORCE_VINTF_MANIFEST)))
 
@@ -231,6 +237,7 @@
 $(call add_json_list, BoardKernelModuleInterfaceVersions, $(BOARD_KERNEL_MODULE_INTERFACE_VERSIONS))
 
 $(call add_json_bool, BoardMoveRecoveryResourcesToVendorBoot, $(BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT))
+$(call add_json_str,  PrebuiltHiddenApiDir, $(BOARD_PREBUILT_HIDDENAPI_DIR))
 
 $(call json_end)
 
diff --git a/target/board/module_arm/device.mk b/target/board/module_arm/device.mk
index 7cac5f8..cceb987 100644
--- a/target/board/module_arm/device.mk
+++ b/target/board/module_arm/device.mk
@@ -14,5 +14,5 @@
 # limitations under the License.
 #
 
-$(call inherit-product, build/make/target/product/bootclasspath.mk)
+$(call inherit-product, build/make/target/product/default_art_config.mk)
 $(call inherit-product, build/make/target/product/languages_default.mk)
diff --git a/target/board/module_arm64/device.mk b/target/board/module_arm64/device.mk
index 9065d4b..0d4c543 100644
--- a/target/board/module_arm64/device.mk
+++ b/target/board/module_arm64/device.mk
@@ -14,6 +14,6 @@
 # limitations under the License.
 #
 
-$(call inherit-product, build/make/target/product/bootclasspath.mk)
+$(call inherit-product, build/make/target/product/default_art_config.mk)
 $(call inherit-product, build/make/target/product/core_64_bit.mk)
 $(call inherit-product, build/make/target/product/languages_default.mk)
diff --git a/target/board/module_x86/device.mk b/target/board/module_x86/device.mk
index 7cac5f8..cceb987 100644
--- a/target/board/module_x86/device.mk
+++ b/target/board/module_x86/device.mk
@@ -14,5 +14,5 @@
 # limitations under the License.
 #
 
-$(call inherit-product, build/make/target/product/bootclasspath.mk)
+$(call inherit-product, build/make/target/product/default_art_config.mk)
 $(call inherit-product, build/make/target/product/languages_default.mk)
diff --git a/target/board/module_x86_64/device.mk b/target/board/module_x86_64/device.mk
index 9065d4b..0d4c543 100644
--- a/target/board/module_x86_64/device.mk
+++ b/target/board/module_x86_64/device.mk
@@ -14,6 +14,6 @@
 # limitations under the License.
 #
 
-$(call inherit-product, build/make/target/product/bootclasspath.mk)
+$(call inherit-product, build/make/target/product/default_art_config.mk)
 $(call inherit-product, build/make/target/product/core_64_bit.mk)
 $(call inherit-product, build/make/target/product/languages_default.mk)
diff --git a/target/product/base_system.mk b/target/product/base_system.mk
index 2660d69..c7ae1f0 100644
--- a/target/product/base_system.mk
+++ b/target/product/base_system.mk
@@ -400,5 +400,4 @@
 PRODUCT_COPY_FILES += $(call add-to-product-copy-files-if-exists,\
     frameworks/base/config/dirty-image-objects:system/etc/dirty-image-objects)
 
-$(call inherit-product, $(SRC_TARGET_DIR)/product/bootclasspath.mk)
 $(call inherit-product, $(SRC_TARGET_DIR)/product/runtime_libart.mk)
diff --git a/target/product/bootclasspath.mk b/target/product/default_art_config.mk
similarity index 82%
rename from target/product/bootclasspath.mk
rename to target/product/default_art_config.mk
index 60dd071..131ba31 100644
--- a/target/product/bootclasspath.mk
+++ b/target/product/default_art_config.mk
@@ -47,3 +47,12 @@
 else
   PRODUCT_BOOT_JARS += android.test.base
 endif
+
+# Minimal configuration for running dex2oat (default argument values).
+# PRODUCT_USES_DEFAULT_ART_CONFIG must be true to enable boot image compilation.
+PRODUCT_USES_DEFAULT_ART_CONFIG := true
+PRODUCT_SYSTEM_PROPERTIES += \
+    dalvik.vm.image-dex2oat-Xms=64m \
+    dalvik.vm.image-dex2oat-Xmx=64m \
+    dalvik.vm.dex2oat-Xms=64m \
+    dalvik.vm.dex2oat-Xmx=512m \
diff --git a/target/product/gsi_release.mk b/target/product/gsi_release.mk
index 241b6ba..2c74ce0 100644
--- a/target/product/gsi_release.mk
+++ b/target/product/gsi_release.mk
@@ -37,9 +37,6 @@
 # Enable dynamic partition size
 PRODUCT_USE_DYNAMIC_PARTITION_SIZE := true
 
-# Needed by Pi newly launched device to pass VtsTrebleSysProp on GSI
-PRODUCT_COMPATIBLE_PROPERTY_OVERRIDE := true
-
 # GSI targets should install "unflattened" APEXes in /system
 TARGET_FLATTEN_APEX := false
 
diff --git a/target/product/runtime_libart.mk b/target/product/runtime_libart.mk
index 687e9f6..4da8794 100644
--- a/target/product/runtime_libart.mk
+++ b/target/product/runtime_libart.mk
@@ -16,6 +16,8 @@
 
 # Provides a functioning ART environment without Android frameworks
 
+$(call inherit-product, $(SRC_TARGET_DIR)/product/default_art_config.mk)
+
 # Additional mixins to the boot classpath.
 PRODUCT_PACKAGES += \
     android.test.base \
@@ -41,10 +43,6 @@
     hiddenapi-package-whitelist.xml \
 
 PRODUCT_SYSTEM_PROPERTIES += \
-    dalvik.vm.image-dex2oat-Xms=64m \
-    dalvik.vm.image-dex2oat-Xmx=64m \
-    dalvik.vm.dex2oat-Xms=64m \
-    dalvik.vm.dex2oat-Xmx=512m \
     dalvik.vm.usejit=true \
     dalvik.vm.usejitprofiles=true \
     dalvik.vm.dexopt.secondary=true \
@@ -96,5 +94,3 @@
 PRODUCT_SYSTEM_PROPERTIES += \
     dalvik.vm.minidebuginfo=true \
     dalvik.vm.dex2oat-minidebuginfo=true
-
-PRODUCT_USES_DEFAULT_ART_CONFIG := true