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)