diff --git a/CleanSpec.mk b/CleanSpec.mk
index f43fa0e..b899bcd 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -646,6 +646,8 @@
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/odm/build.prop)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/vendor/odm/build.prop)
 
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/apex)
+
 # ************************************************
 # NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST
 # ************************************************
diff --git a/core/build_id.mk b/core/build_id.mk
index 2329288..2f9c3f3 100644
--- a/core/build_id.mk
+++ b/core/build_id.mk
@@ -18,4 +18,4 @@
 # (like "CRB01").  It must be a single word, and is
 # capitalized by convention.
 
-BUILD_ID=QT
+BUILD_ID=MASTER
diff --git a/target/board/mainline_arm64/BoardConfig.mk b/target/board/mainline_arm64/BoardConfig.mk
index 70505f4..ea2b3c5 100644
--- a/target/board/mainline_arm64/BoardConfig.mk
+++ b/target/board/mainline_arm64/BoardConfig.mk
@@ -34,3 +34,8 @@
 
 BOARD_VENDORIMAGE_FILE_SYSTEM_TYPE := ext4
 BOARD_PRODUCTIMAGE_FILE_SYSTEM_TYPE := ext4
+
+# Mainline devices support apex
+# TODO: move this to BoardConfigMainlineCommon. Currently, GSI wants flattened
+#       apexes, but emulator wants .apex files, preventing this.
+TARGET_FLATTEN_APEX := false
diff --git a/target/product/emulator_system.mk b/target/product/emulator_system.mk
new file mode 100644
index 0000000..4b6987c
--- /dev/null
+++ b/target/product/emulator_system.mk
@@ -0,0 +1,24 @@
+#
+# Copyright (C) 2019 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.
+#
+# This file lists emulator experimental modules added to PRODUCT_PACKAGES,
+# only included by targets sdk_phone_x86/64 and sdk_gphone_x86/64
+
+PRODUCT_ARTIFACT_PATH_REQUIREMENT_WHITELIST := \
+    system/lib/libemulator_multidisplay_jni.so \
+    system/lib64/libemulator_multidisplay_jni.so \
+    system/priv-app/MultiDisplayProvider/MultiDisplayProvider.apk \
+
+PRODUCT_PACKAGES += MultiDisplayProvider
diff --git a/target/product/runtime_libart.mk b/target/product/runtime_libart.mk
index 5db32f2..8151d49 100644
--- a/target/product/runtime_libart.mk
+++ b/target/product/runtime_libart.mk
@@ -94,6 +94,6 @@
 
 # Disable iorapd by default
 PRODUCT_SYSTEM_DEFAULT_PROPERTIES += \
-    ro.iorapd.enable=false
+    ro.iorapd.enable=true
 
 PRODUCT_USES_DEFAULT_ART_CONFIG := true