diff --git a/target/board/generic/BoardConfig.mk b/target/board/generic/BoardConfig.mk
index 1d09c2e35..5614f4655 100644
--- a/target/board/generic/BoardConfig.mk
+++ b/target/board/generic/BoardConfig.mk
@@ -32,15 +32,6 @@ TARGET_USES_64_BIT_BINDER := true
 # no hardware camera
 USE_CAMERA_STUB := true
 
-# Enable dex-preoptimization to speed up the first boot sequence
-# of an SDK AVD. Note that this operation only works on Linux for now
-ifeq ($(HOST_OS),linux)
-  ifeq ($(WITH_DEXPREOPT),)
-    WITH_DEXPREOPT := true
-    WITH_DEXPREOPT_BOOT_IMG_AND_SYSTEM_SERVER_ONLY := false
-  endif
-endif
-
 TARGET_USES_HWC2 := true
 NUM_FRAMEBUFFER_SURFACE_BUFFERS := 3
 
@@ -53,7 +44,8 @@ BUILD_QEMU_IMAGES := true
 USE_OPENGL_RENDERER := true
 
 TARGET_USERIMAGES_USE_EXT4 := true
-BOARD_SYSTEMIMAGE_PARTITION_SIZE := 2147483648  # 2 GB
+# Partition size is default 1.5GB (1536MB) for 64 bits projects
+BOARD_SYSTEMIMAGE_PARTITION_SIZE := 1610612736
 BOARD_USERDATAIMAGE_PARTITION_SIZE := 576716800
 TARGET_COPY_OUT_VENDOR := vendor
 # ~100 MB vendor image. Please adjust system image / vendor image sizes
@@ -67,6 +59,13 @@ DEVICE_MATRIX_FILE   := device/generic/goldfish/compatibility_matrix.xml
 BOARD_SEPOLICY_DIRS += build/target/board/generic/sepolicy
 BOARD_PROPERTY_OVERRIDES_SPLIT_ENABLED := true
 
+ifneq (,$(filter userdebug eng,$(TARGET_BUILD_VARIANT)))
+# GSI is always userdebug and needs a couple of properties taking precedence
+# over those set by the vendor.
+TARGET_SYSTEM_PROP := build/make/target/board/treble_system.prop
+endif
+BOARD_VNDK_VERSION := current
+
 # Wifi.
 BOARD_WLAN_DEVICE           := emulator
 BOARD_HOSTAPD_DRIVER        := NL80211
diff --git a/target/board/generic/device.mk b/target/board/generic/device.mk
index f3ad03be7..d2f631090 100644
--- a/target/board/generic/device.mk
+++ b/target/board/generic/device.mk
@@ -23,11 +23,11 @@ PRODUCT_PROPERTY_OVERRIDES := \
 
 PRODUCT_COPY_FILES := \
     device/generic/goldfish/data/etc/apns-conf.xml:system/etc/apns-conf.xml \
-    device/generic/goldfish/camera/media_profiles.xml:system/etc/media_profiles.xml \
-    frameworks/av/media/libstagefright/data/media_codecs_google_audio.xml:system/etc/media_codecs_google_audio.xml \
-    frameworks/av/media/libstagefright/data/media_codecs_google_telephony.xml:system/etc/media_codecs_google_telephony.xml \
-    frameworks/av/media/libstagefright/data/media_codecs_google_video.xml:system/etc/media_codecs_google_video.xml \
-    device/generic/goldfish/camera/media_codecs.xml:system/etc/media_codecs.xml \
+    device/generic/goldfish/camera/media_profiles.xml:$(TARGET_COPY_OUT_VENDOR)/etc/media_profiles.xml \
+    frameworks/av/media/libstagefright/data/media_codecs_google_audio.xml:$(TARGET_COPY_OUT_VENDOR)/etc/media_codecs_google_audio.xml \
+    frameworks/av/media/libstagefright/data/media_codecs_google_telephony.xml:$(TARGET_COPY_OUT_VENDOR)/etc/media_codecs_google_telephony.xml \
+    frameworks/av/media/libstagefright/data/media_codecs_google_video.xml:$(TARGET_COPY_OUT_VENDOR)/etc/media_codecs_google_video.xml \
+    device/generic/goldfish/camera/media_codecs.xml:$(TARGET_COPY_OUT_VENDOR)/etc/media_codecs.xml \
     hardware/libhardware_legacy/audio/audio_policy.conf:system/etc/audio_policy.conf
 
 # minimal configuration for audio policy.
diff --git a/target/board/generic_arm64/BoardConfig.mk b/target/board/generic_arm64/BoardConfig.mk
index d5f79f4ae..824f6a7af 100644
--- a/target/board/generic_arm64/BoardConfig.mk
+++ b/target/board/generic_arm64/BoardConfig.mk
@@ -61,15 +61,6 @@ TARGET_USES_64_BIT_BINDER := true
 # no hardware camera
 USE_CAMERA_STUB := true
 
-# Enable dex-preoptimization to speed up the first boot sequence
-# of an SDK AVD. Note that this operation only works on Linux for now
-ifeq ($(HOST_OS),linux)
-  ifeq ($(WITH_DEXPREOPT),)
-    WITH_DEXPREOPT := true
-    WITH_DEXPREOPT_BOOT_IMG_AND_SYSTEM_SERVER_ONLY := false
-  endif
-endif
-
 TARGET_USES_HWC2 := true
 NUM_FRAMEBUFFER_SURFACE_BUFFERS := 3
 
@@ -82,7 +73,8 @@ BUILD_QEMU_IMAGES := true
 USE_OPENGL_RENDERER := true
 
 TARGET_USERIMAGES_USE_EXT4 := true
-BOARD_SYSTEMIMAGE_PARTITION_SIZE := 2684354560  # 2.5 GB
+# Partition size is default 1.5GB (1536MB) for 64 bits projects
+BOARD_SYSTEMIMAGE_PARTITION_SIZE := 1610612736
 BOARD_USERDATAIMAGE_PARTITION_SIZE := 576716800
 TARGET_COPY_OUT_VENDOR := vendor
 # ~100 MB vendor image. Please adjust system image / vendor image sizes
@@ -96,6 +88,24 @@ DEVICE_MATRIX_FILE   := device/generic/goldfish/compatibility_matrix.xml
 BOARD_PROPERTY_OVERRIDES_SPLIT_ENABLED := true
 BOARD_SEPOLICY_DIRS += build/target/board/generic/sepolicy
 
+ifneq (,$(filter userdebug eng,$(TARGET_BUILD_VARIANT)))
+# GSI is always userdebug and needs a couple of properties taking precedence
+# over those set by the vendor.
+TARGET_SYSTEM_PROP := build/make/target/board/treble_system.prop
+endif
+BOARD_VNDK_VERSION := current
+
+# Emulator system image is going to be used as GSI and some vendor still hasn't
+# cleaned up all device specific directories under root!
+
+# TODO(jiyong) These might be SoC specific.
+BOARD_ROOT_EXTRA_FOLDERS += firmware firmware/radio persist
+BOARD_ROOT_EXTRA_SYMLINKS := /vendor/lib/dsp:/dsp
+
+# TODO(b/36764215): remove this setting when the generic system image
+# no longer has QCOM-specific directories under /.
+BOARD_SEPOLICY_DIRS += build/target/board/generic_arm64_ab/sepolicy
+
 # Wifi.
 BOARD_WLAN_DEVICE           := emulator
 BOARD_HOSTAPD_DRIVER        := NL80211
diff --git a/target/board/generic_arm64/device.mk b/target/board/generic_arm64/device.mk
index 4e33d3b9b..8d62f4bff 100644
--- a/target/board/generic_arm64/device.mk
+++ b/target/board/generic_arm64/device.mk
@@ -23,11 +23,11 @@ PRODUCT_PROPERTY_OVERRIDES := \
 
 PRODUCT_COPY_FILES := \
     device/generic/goldfish/data/etc/apns-conf.xml:system/etc/apns-conf.xml \
-    device/generic/goldfish/camera/media_profiles.xml:system/etc/media_profiles.xml \
-    frameworks/av/media/libstagefright/data/media_codecs_google_audio.xml:system/etc/media_codecs_google_audio.xml \
-    frameworks/av/media/libstagefright/data/media_codecs_google_telephony.xml:system/etc/media_codecs_google_telephony.xml \
-    frameworks/av/media/libstagefright/data/media_codecs_google_video.xml:system/etc/media_codecs_google_video.xml \
-    device/generic/goldfish/camera/media_codecs.xml:system/etc/media_codecs.xml
+    device/generic/goldfish/camera/media_profiles.xml:$(TARGET_COPY_OUT_VENDOR)/etc/media_profiles.xml \
+    frameworks/av/media/libstagefright/data/media_codecs_google_audio.xml:$(TARGET_COPY_OUT_VENDOR)/etc/media_codecs_google_audio.xml \
+    frameworks/av/media/libstagefright/data/media_codecs_google_telephony.xml:$(TARGET_COPY_OUT_VENDOR)/etc/media_codecs_google_telephony.xml \
+    frameworks/av/media/libstagefright/data/media_codecs_google_video.xml:$(TARGET_COPY_OUT_VENDOR)/etc/media_codecs_google_video.xml \
+    device/generic/goldfish/camera/media_codecs.xml:$(TARGET_COPY_OUT_VENDOR)/etc/media_codecs.xml
 
 # minimal configuration for audio policy.
 PRODUCT_COPY_FILES += \