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/BoardConfigGsiCommon.mk b/target/board/BoardConfigGsiCommon.mk
index 96fd07b..a26b2b7 100644
--- a/target/board/BoardConfigGsiCommon.mk
+++ b/target/board/BoardConfigGsiCommon.mk
@@ -52,7 +52,3 @@
 
 # Disable 64 bit mediadrmserver
 TARGET_ENABLE_MEDIADRM_64 :=
-
-# Ordinary (non-flattened) APEX may require kernel changes. For maximum compatibility,
-# use flattened APEX for GSI
-TARGET_FLATTEN_APEX := true
diff --git a/target/board/BoardConfigMainlineCommon.mk b/target/board/BoardConfigMainlineCommon.mk
index be014bf..be7c804 100644
--- a/target/board/BoardConfigMainlineCommon.mk
+++ b/target/board/BoardConfigMainlineCommon.mk
@@ -41,6 +41,3 @@
 
 # Generate an APEX image for experiment b/119800099.
 DEXPREOPT_GENERATE_APEX_IMAGE := true
-
-# Mainline devices support apex
-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/mainline_system.mk b/target/product/mainline_system.mk
index 0949616..4b4bfda 100644
--- a/target/product/mainline_system.mk
+++ b/target/product/mainline_system.mk
@@ -18,8 +18,6 @@
 $(call inherit-product, $(SRC_TARGET_DIR)/product/handheld_system.mk)
 $(call inherit-product, $(SRC_TARGET_DIR)/product/telephony_system.mk)
 $(call inherit-product, $(SRC_TARGET_DIR)/product/languages_default.mk)
-# Enable updating of APEXes
-#$(call inherit-product, $(SRC_TARGET_DIR)/product/updatable_apex.mk)
 # Add adb keys to debuggable AOSP builds (if they exist)
 $(call inherit-product-if-exists, vendor/google/security/adb/vendor_key.mk)
 
@@ -110,6 +108,9 @@
 # Enable dynamic partition size
 PRODUCT_USE_DYNAMIC_PARTITION_SIZE := true
 
+PRODUCT_PACKAGES += \
+    com.android.apex.cts.shim.v1_prebuilt
+
 PRODUCT_NAME := mainline_system
 PRODUCT_BRAND := generic
 
diff --git a/target/product/updatable_apex.mk b/target/product/updatable_apex.mk
index 038f66e..a9f4baf 100644
--- a/target/product/updatable_apex.mk
+++ b/target/product/updatable_apex.mk
@@ -17,5 +17,4 @@
 # Inherit this when the target needs to support updating APEXes
 
 PRODUCT_PROPERTY_OVERRIDES := ro.apex.updatable=true
-PRODUCT_PACKAGES := com.android.apex.cts.shim.v1_prebuilt
 TARGET_FLATTEN_APEX := false