diff --git a/fs_mgr/Android.bp b/fs_mgr/Android.bp
index 5356b00..3d63a44 100644
--- a/fs_mgr/Android.bp
+++ b/fs_mgr/Android.bp
@@ -141,6 +141,7 @@
     // Do not ever allow this library to be vendor_available as a shared library.
     // It does not have a stable interface.
     name: "libfs_mgr",
+    ramdisk_available: true,
     recovery_available: true,
     defaults: [
         "libfs_mgr_defaults",
@@ -165,6 +166,7 @@
     // It does not have a stable interface.
     name: "libfstab",
     vendor_available: true,
+    ramdisk_available: true,
     recovery_available: true,
     host_supported: true,
     defaults: ["fs_mgr_defaults"],
diff --git a/fs_mgr/libfiemap/Android.bp b/fs_mgr/libfiemap/Android.bp
index 1c5872e..b62e33f 100644
--- a/fs_mgr/libfiemap/Android.bp
+++ b/fs_mgr/libfiemap/Android.bp
@@ -20,6 +20,7 @@
 
 cc_library_headers {
     name: "libfiemap_headers",
+    ramdisk_available: true,
     recovery_available: true,
     export_include_dirs: ["include"],
 }
diff --git a/fs_mgr/libfs_avb/Android.bp b/fs_mgr/libfs_avb/Android.bp
index 6892025..62493eb 100644
--- a/fs_mgr/libfs_avb/Android.bp
+++ b/fs_mgr/libfs_avb/Android.bp
@@ -27,6 +27,7 @@
 cc_library_static {
     name: "libfs_avb",
     defaults: ["fs_mgr_defaults"],
+    ramdisk_available: true,
     recovery_available: true,
     host_supported: true,
     export_include_dirs: ["include"],
diff --git a/fs_mgr/liblp/Android.bp b/fs_mgr/liblp/Android.bp
index 7e528b1..86ca8f3 100644
--- a/fs_mgr/liblp/Android.bp
+++ b/fs_mgr/liblp/Android.bp
@@ -30,6 +30,7 @@
 cc_library {
     name: "liblp",
     host_supported: true,
+    ramdisk_available: true,
     recovery_available: true,
     defaults: ["fs_mgr_defaults"],
     cppflags: [
diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index 6a764e4..aa1f415 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -118,6 +118,7 @@
     native_coverage : true,
     defaults: ["libsnapshot_defaults"],
     srcs: [":libsnapshot_sources"],
+    ramdisk_available: true,
     recovery_available: true,
     cflags: [
         "-DLIBSNAPSHOT_NO_COW_WRITE",
diff --git a/fs_mgr/libstorage_literals/Android.bp b/fs_mgr/libstorage_literals/Android.bp
index 5b07168..fd7ea04 100644
--- a/fs_mgr/libstorage_literals/Android.bp
+++ b/fs_mgr/libstorage_literals/Android.bp
@@ -6,6 +6,7 @@
 cc_library_headers {
     name: "libstorage_literals_headers",
     host_supported: true,
+    ramdisk_available: true,
     recovery_available: true,
     export_include_dirs: ["."],
     target: {
diff --git a/init/Android.bp b/init/Android.bp
index 7eeafa2..d0b58ca 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -253,11 +253,32 @@
     visibility: ["//packages/modules/Virtualization/microdroid"],
 }
 
-// This currently is only for the VM usecase.
-// TODO(jiyong): replace init_first_stage in Android.mk with this
+soong_config_module_type {
+    name: "init_first_stage_cc_defaults",
+    module_type: "cc_defaults",
+    config_namespace: "ANDROID",
+    bool_variables: ["BOARD_BUILD_SYSTEM_ROOT_IMAGE", "BOARD_USES_RECOVERY_AS_BOOT"],
+    properties: ["installable"],
+}
+
+// Do not install init_first_stage even with mma if we're system-as-root.
+// Otherwise, it will overwrite the symlink.
+init_first_stage_cc_defaults {
+    name: "init_first_stage_defaults",
+    soong_config_variables: {
+        BOARD_BUILD_SYSTEM_ROOT_IMAGE: {
+            installable: false,
+        },
+        BOARD_USES_RECOVERY_AS_BOOT: {
+            installable: false,
+        },
+    },
+}
+
 cc_binary {
-    name: "init_first_stage_soong",
-    stem: "init_vendor",
+    name: "init_first_stage",
+    stem: "init",
+    defaults: ["init_first_stage_defaults"],
 
     srcs: [
         "block_dev_initializer.cpp",
@@ -313,6 +334,7 @@
     ],
 
     static_executable: true,
+    system_shared_libs: [],
 
     cflags: [
         "-Wall",
@@ -363,8 +385,23 @@
 
     sanitize: {
         misc_undefined: ["signed-integer-overflow"],
+
+        // First stage init is weird: it may start without stdout/stderr, and no /proc.
         hwaddress: false,
     },
+
+    // Install adb_debug.prop into debug ramdisk.
+    // This allows adb root on a user build, when debug ramdisk is used.
+    required: ["adb_debug.prop"],
+
+    ramdisk: true,
+
+    install_in_root: true,
+}
+
+phony {
+    name: "init_system",
+    required: ["init_second_stage"],
 }
 
 // Tests
diff --git a/init/Android.mk b/init/Android.mk
index 3c7d95a..c08fe03 100644
--- a/init/Android.mk
+++ b/init/Android.mk
@@ -2,153 +2,6 @@
 
 LOCAL_PATH:= $(call my-dir)
 
--include system/sepolicy/policy_version.mk
-
-# --
-
-ifneq (,$(filter userdebug eng,$(TARGET_BUILD_VARIANT)))
-init_options += \
-    -DALLOW_FIRST_STAGE_CONSOLE=1 \
-    -DALLOW_LOCAL_PROP_OVERRIDE=1 \
-    -DALLOW_PERMISSIVE_SELINUX=1 \
-    -DREBOOT_BOOTLOADER_ON_PANIC=1 \
-    -DWORLD_WRITABLE_KMSG=1 \
-    -DDUMP_ON_UMOUNT_FAILURE=1
-else
-init_options += \
-    -DALLOW_FIRST_STAGE_CONSOLE=0 \
-    -DALLOW_LOCAL_PROP_OVERRIDE=0 \
-    -DALLOW_PERMISSIVE_SELINUX=0 \
-    -DREBOOT_BOOTLOADER_ON_PANIC=0 \
-    -DWORLD_WRITABLE_KMSG=0 \
-    -DDUMP_ON_UMOUNT_FAILURE=0
-endif
-
-ifneq (,$(filter eng,$(TARGET_BUILD_VARIANT)))
-init_options += \
-    -DSHUTDOWN_ZERO_TIMEOUT=1
-else
-init_options += \
-    -DSHUTDOWN_ZERO_TIMEOUT=0
-endif
-
-init_options += -DLOG_UEVENTS=0 \
-    -DSEPOLICY_VERSION=$(POLICYVERS)
-
-init_cflags += \
-    $(init_options) \
-    -Wall -Wextra \
-    -Wno-unused-parameter \
-    -Werror \
-
-# --
-
-# Do not build this even with mmma if we're system-as-root, otherwise it will overwrite the symlink.
-ifneq ($(BOARD_BUILD_SYSTEM_ROOT_IMAGE),true)
-include $(CLEAR_VARS)
-LOCAL_CPPFLAGS := $(init_cflags)
-LOCAL_SRC_FILES := \
-    block_dev_initializer.cpp \
-    devices.cpp \
-    first_stage_console.cpp \
-    first_stage_init.cpp \
-    first_stage_main.cpp \
-    first_stage_mount.cpp \
-    reboot_utils.cpp \
-    selabel.cpp \
-    selinux.cpp \
-    service_utils.cpp \
-    snapuserd_transition.cpp \
-    switch_root.cpp \
-    uevent_listener.cpp \
-    util.cpp \
-
-LOCAL_MODULE := init_first_stage
-LOCAL_LICENSE_KINDS := SPDX-license-identifier-Apache-2.0
-LOCAL_LICENSE_CONDITIONS := notice
-LOCAL_NOTICE_FILE := $(LOCAL_PATH)/NOTICE
-LOCAL_MODULE_STEM := init
-
-LOCAL_FORCE_STATIC_EXECUTABLE := true
-
-LOCAL_MODULE_PATH := $(TARGET_RAMDISK_OUT)
-LOCAL_UNSTRIPPED_PATH := $(TARGET_RAMDISK_OUT_UNSTRIPPED)
-
-# Install adb_debug.prop into debug ramdisk.
-# This allows adb root on a user build, when debug ramdisk is used.
-LOCAL_REQUIRED_MODULES := \
-   adb_debug.prop \
-
-# Set up the directories that first stage init mounts on.
-
-my_ramdisk_dirs := \
-    debug_ramdisk \
-    dev \
-    metadata \
-    mnt \
-    proc \
-    second_stage_resources \
-    sys \
-
-LOCAL_POST_INSTALL_CMD := mkdir -p $(addprefix $(TARGET_RAMDISK_OUT)/,$(my_ramdisk_dirs))
-ifeq (true,$(BOARD_USES_GENERIC_KERNEL_IMAGE))
-    LOCAL_POST_INSTALL_CMD += $(addprefix $(TARGET_RAMDISK_OUT)/first_stage_ramdisk/,$(my_ramdisk_dirs))
-endif
-
-my_ramdisk_dirs :=
-
-LOCAL_STATIC_LIBRARIES := \
-    libc++fs \
-    libfs_avb \
-    libfs_mgr \
-    libfec \
-    libfec_rs \
-    libsquashfs_utils \
-    liblogwrap \
-    libext4_utils \
-    libcrypto_utils \
-    libsparse \
-    libavb \
-    libkeyutils \
-    liblp \
-    libcutils \
-    libbase \
-    liblog \
-    libcrypto_static \
-    libdl \
-    libz \
-    libselinux \
-    libcap \
-    libgsi \
-    libcom.android.sysprop.apex \
-    liblzma \
-    libunwindstack_no_dex \
-    libbacktrace_no_dex \
-    libmodprobe \
-    libext2_uuid \
-    libprotobuf-cpp-lite \
-    libsnapshot_cow \
-    libsnapshot_init \
-    update_metadata-protos \
-    libprocinfo \
-
-LOCAL_SANITIZE := signed-integer-overflow
-# First stage init is weird: it may start without stdout/stderr, and no /proc.
-LOCAL_NOSANITIZE := hwaddress
-include $(BUILD_EXECUTABLE)
-endif
-
-include $(CLEAR_VARS)
-
-LOCAL_MODULE := init_system
-LOCAL_LICENSE_KINDS := SPDX-license-identifier-Apache-2.0
-LOCAL_LICENSE_CONDITIONS := notice
-LOCAL_NOTICE_FILE := $(LOCAL_PATH)/NOTICE
-LOCAL_REQUIRED_MODULES := \
-   init_second_stage \
-
-include $(BUILD_PHONY_PACKAGE)
-
 include $(CLEAR_VARS)
 
 LOCAL_MODULE := init_vendor
@@ -156,8 +9,10 @@
 LOCAL_LICENSE_CONDITIONS := notice
 LOCAL_NOTICE_FILE := $(LOCAL_PATH)/NOTICE
 ifneq ($(BOARD_BUILD_SYSTEM_ROOT_IMAGE),true)
+ifneq ($(BOARD_USES_RECOVERY_AS_BOOT),true)
 LOCAL_REQUIRED_MODULES := \
    init_first_stage \
 
-endif
+endif  # BOARD_USES_RECOVERY_AS_BOOT
+endif  # BOARD_BUILD_SYSTEM_ROOT_IMAGE
 include $(BUILD_PHONY_PACKAGE)
diff --git a/libcrypto_utils/Android.bp b/libcrypto_utils/Android.bp
index b33d46d..c8a183b 100644
--- a/libcrypto_utils/Android.bp
+++ b/libcrypto_utils/Android.bp
@@ -21,6 +21,7 @@
 cc_library {
     name: "libcrypto_utils",
     vendor_available: true,
+    ramdisk_available: true,
     recovery_available: true,
     vndk: {
         enabled: true,
diff --git a/libkeyutils/Android.bp b/libkeyutils/Android.bp
index 86f68fb..a940b8c 100644
--- a/libkeyutils/Android.bp
+++ b/libkeyutils/Android.bp
@@ -15,6 +15,7 @@
     name: "libkeyutils",
     cflags: ["-Werror"],
     defaults: ["linux_bionic_supported"],
+    ramdisk_available: true,
     recovery_available: true,
     export_include_dirs: ["include/"],
     local_include_dirs: ["include/"],
diff --git a/libmodprobe/Android.bp b/libmodprobe/Android.bp
index ba11dc9..525a880 100644
--- a/libmodprobe/Android.bp
+++ b/libmodprobe/Android.bp
@@ -8,6 +8,7 @@
         "-Werror",
     ],
     vendor_available: true,
+    ramdisk_available: true,
     recovery_available: true,
     srcs: [
         "libmodprobe.cpp",
diff --git a/rootdir/Android.bp b/rootdir/Android.bp
index ae21633..e98733a 100644
--- a/rootdir/Android.bp
+++ b/rootdir/Android.bp
@@ -45,4 +45,11 @@
     src: "etc/public.libraries.android.txt",
     filename: "public.libraries.txt",
     installable: false,
-}
\ No newline at end of file
+}
+
+// adb_debug.prop in debug ramdisk
+prebuilt_root {
+    name: "adb_debug.prop",
+    src: "adb_debug.prop",
+    debug_ramdisk: true,
+}
diff --git a/rootdir/Android.mk b/rootdir/Android.mk
index 99d8f9a..9b80575 100644
--- a/rootdir/Android.mk
+++ b/rootdir/Android.mk
@@ -210,15 +210,4 @@
 	$(hide) $(foreach lib,$(PRIVATE_SANITIZER_RUNTIME_LIBRARIES), \
 		echo $(lib) >> $@;)
 
-#######################################
-# adb_debug.prop in debug ramdisk
-include $(CLEAR_VARS)
-LOCAL_MODULE := adb_debug.prop
-LOCAL_LICENSE_KINDS := SPDX-license-identifier-Apache-2.0
-LOCAL_LICENSE_CONDITIONS := notice
-LOCAL_SRC_FILES := $(LOCAL_MODULE)
-LOCAL_MODULE_CLASS := ETC
-LOCAL_MODULE_PATH := $(TARGET_DEBUG_RAMDISK_OUT)
-include $(BUILD_PREBUILT)
-
 include $(call all-makefiles-under,$(LOCAL_PATH))