diff --git a/tools/releasetools/merge/Android.bp b/tools/releasetools/merge/Android.bp
index c07d8ee..219acf8 100644
--- a/tools/releasetools/merge/Android.bp
+++ b/tools/releasetools/merge/Android.bp
@@ -19,14 +19,20 @@
 filegroup {
     name: "releasetools_merge_sources",
     srcs: [
+        "merge_compatibility_checks.py",
+        "merge_dexopt.py",
+        "merge_meta.py",
         "merge_target_files.py",
+        "merge_utils.py",
     ],
 }
 
 filegroup {
     name: "releasetools_merge_tests",
     srcs: [
-        "test_merge_target_files.py",
+        "test_merge_compatibility_checks.py",
+        "test_merge_meta.py",
+        "test_merge_utils.py",
     ],
 }
 
diff --git a/tools/releasetools/merge/merge_compatibility_checks.py b/tools/releasetools/merge/merge_compatibility_checks.py
new file mode 100644
index 0000000..207abe2
--- /dev/null
+++ b/tools/releasetools/merge/merge_compatibility_checks.py
@@ -0,0 +1,206 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2022 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.
+#
+"""Compatibility checks that should be performed on merged target_files."""
+
+import json
+import logging
+import os
+from xml.etree import ElementTree
+
+import apex_utils
+import check_target_files_vintf
+import common
+import find_shareduid_violation
+
+logger = logging.getLogger(__name__)
+OPTIONS = common.OPTIONS
+
+
+def CheckCompatibility(target_files_dir, partition_map):
+  """Runs various compatibility checks.
+
+  Returns a possibly-empty list of error messages.
+  """
+  errors = []
+
+  errors.extend(CheckVintf(target_files_dir))
+  errors.extend(CheckShareduidViolation(target_files_dir, partition_map))
+  errors.extend(CheckApexDuplicatePackages(target_files_dir, partition_map))
+
+  # The remaining checks only use the following partitions:
+  partition_map = {
+      partition: path
+      for partition, path in partition_map.items()
+      if partition in ('system', 'system_ext', 'product', 'vendor', 'odm')
+  }
+
+  errors.extend(CheckInitRcFiles(target_files_dir, partition_map))
+  errors.extend(CheckCombinedSepolicy(target_files_dir, partition_map))
+
+  return errors
+
+
+def CheckVintf(target_files_dir):
+  """Check for any VINTF issues using check_vintf."""
+  errors = []
+  try:
+    if not check_target_files_vintf.CheckVintf(target_files_dir):
+      errors.append('Incompatible VINTF.')
+  except RuntimeError as err:
+    errors.append(str(err))
+  return errors
+
+
+def CheckShareduidViolation(target_files_dir, partition_map):
+  """Check for any APK sharedUserId violations across partition sets.
+
+  Writes results to META/shareduid_violation_modules.json to help
+  with followup debugging.
+  """
+  errors = []
+  violation = find_shareduid_violation.FindShareduidViolation(
+      target_files_dir, partition_map)
+  shareduid_violation_modules = os.path.join(
+      target_files_dir, 'META', 'shareduid_violation_modules.json')
+  with open(shareduid_violation_modules, 'w') as f:
+    # Write the output to a file to enable debugging.
+    f.write(violation)
+
+    # Check for violations across the partition sets.
+    shareduid_errors = common.SharedUidPartitionViolations(
+        json.loads(violation),
+        [OPTIONS.framework_partition_set, OPTIONS.vendor_partition_set])
+    if shareduid_errors:
+      for error in shareduid_errors:
+        errors.append('APK sharedUserId error: %s' % error)
+      errors.append('See APK sharedUserId violations file: %s' %
+                    shareduid_violation_modules)
+  return errors
+
+
+def CheckInitRcFiles(target_files_dir, partition_map):
+  """Check for any init.rc issues using host_init_verifier."""
+  try:
+    common.RunHostInitVerifier(
+        product_out=target_files_dir, partition_map=partition_map)
+  except RuntimeError as err:
+    return [str(err)]
+  return []
+
+
+def CheckCombinedSepolicy(target_files_dir, partition_map, execute=True):
+  """Uses secilc to compile a split sepolicy file.
+
+  Depends on various */etc/selinux/* and */etc/vintf/* files within partitions.
+  """
+  errors = []
+
+  def get_file(partition, path):
+    if partition not in partition_map:
+      logger.warning('Cannot load SEPolicy files for missing partition %s',
+                     partition)
+      return None
+    file_path = os.path.join(target_files_dir, partition_map[partition], path)
+    if os.path.exists(file_path):
+      return file_path
+    return None
+
+  # Load the kernel sepolicy version from the FCM. This is normally provided
+  # directly to selinux.cpp as a build flag, but is also available in this file.
+  fcm_file = get_file('system', 'etc/vintf/compatibility_matrix.device.xml')
+  if not fcm_file:
+    errors.append('Missing required file for loading sepolicy: '
+                  '/system/etc/vintf/compatibility_matrix.device.xml')
+    return errors
+  kernel_sepolicy_version = ElementTree.parse(fcm_file).getroot().find(
+      'sepolicy/kernel-sepolicy-version').text
+
+  # Load the vendor's plat sepolicy version. This is the version used for
+  # locating sepolicy mapping files.
+  vendor_plat_version_file = get_file('vendor',
+                                      'etc/selinux/plat_sepolicy_vers.txt')
+  if not vendor_plat_version_file:
+    errors.append('Missing required sepolicy file %s' %
+                  vendor_plat_version_file)
+    return errors
+  with open(vendor_plat_version_file) as f:
+    vendor_plat_version = f.read().strip()
+
+  # Use the same flags and arguments as selinux.cpp OpenSplitPolicy().
+  cmd = ['secilc', '-m', '-M', 'true', '-G', '-N']
+  cmd.extend(['-c', kernel_sepolicy_version])
+  cmd.extend(['-o', os.path.join(target_files_dir, 'META/combined_sepolicy')])
+  cmd.extend(['-f', '/dev/null'])
+
+  required_policy_files = (
+      ('system', 'etc/selinux/plat_sepolicy.cil'),
+      ('system', 'etc/selinux/mapping/%s.cil' % vendor_plat_version),
+      ('vendor', 'etc/selinux/vendor_sepolicy.cil'),
+      ('vendor', 'etc/selinux/plat_pub_versioned.cil'),
+  )
+  for policy in (map(lambda partition_and_path: get_file(*partition_and_path),
+                     required_policy_files)):
+    if not policy:
+      errors.append('Missing required sepolicy file %s' % policy)
+      return errors
+    cmd.append(policy)
+
+  optional_policy_files = (
+      ('system', 'etc/selinux/mapping/%s.compat.cil' % vendor_plat_version),
+      ('system_ext', 'etc/selinux/system_ext_sepolicy.cil'),
+      ('system_ext', 'etc/selinux/mapping/%s.cil' % vendor_plat_version),
+      ('product', 'etc/selinux/product_sepolicy.cil'),
+      ('product', 'etc/selinux/mapping/%s.cil' % vendor_plat_version),
+      ('odm', 'etc/selinux/odm_sepolicy.cil'),
+  )
+  for policy in (map(lambda partition_and_path: get_file(*partition_and_path),
+                     optional_policy_files)):
+    if policy:
+      cmd.append(policy)
+
+  try:
+    if execute:
+      common.RunAndCheckOutput(cmd)
+    else:
+      return cmd
+  except RuntimeError as err:
+    errors.append(str(err))
+
+  return errors
+
+
+def CheckApexDuplicatePackages(target_files_dir, partition_map):
+  """Checks if the same APEX package name is provided by multiple partitions."""
+  errors = []
+
+  apex_packages = set()
+  for partition in partition_map.keys():
+    try:
+      apex_info = apex_utils.GetApexInfoFromTargetFiles(
+          target_files_dir, partition, compressed_only=False)
+    except RuntimeError as err:
+      errors.append(str(err))
+      apex_info = []
+    partition_apex_packages = set([info.package_name for info in apex_info])
+    duplicates = apex_packages.intersection(partition_apex_packages)
+    if duplicates:
+      errors.append(
+          'Duplicate APEX package_names found in multiple partitions: %s' %
+          ' '.join(duplicates))
+    apex_packages.update(partition_apex_packages)
+
+  return errors
diff --git a/tools/releasetools/merge/merge_dexopt.py b/tools/releasetools/merge/merge_dexopt.py
new file mode 100644
index 0000000..dd6e2f9
--- /dev/null
+++ b/tools/releasetools/merge/merge_dexopt.py
@@ -0,0 +1,322 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2022 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.
+#
+"""Generates dexopt files for vendor apps, from a merged target_files.
+
+Expects items in OPTIONS prepared by merge_target_files.py.
+"""
+
+import glob
+import json
+import logging
+import os
+import shutil
+import subprocess
+
+import common
+
+logger = logging.getLogger(__name__)
+OPTIONS = common.OPTIONS
+
+
+def MergeDexopt(temp_dir, output_target_files_dir):
+  """If needed, generates dexopt files for vendor apps.
+
+  Args:
+    temp_dir: Location containing an 'output' directory where target files have
+      been extracted, e.g. <temp_dir>/output/SYSTEM, <temp_dir>/output/IMAGES,
+      etc.
+    output_target_files_dir: The name of a directory that will be used to create
+      the output target files package after all the special cases are processed.
+  """
+  # Load vendor and framework META/misc_info.txt.
+  if (OPTIONS.vendor_misc_info.get('building_with_vsdk') != 'true' or
+      OPTIONS.framework_dexpreopt_tools is None or
+      OPTIONS.framework_dexpreopt_config is None or
+      OPTIONS.vendor_dexpreopt_config is None):
+    return
+
+  logger.info('applying dexpreopt')
+
+  # The directory structure to apply dexpreopt is:
+  #
+  # <temp_dir>/
+  #     framework_meta/
+  #         META/
+  #     vendor_meta/
+  #         META/
+  #     output/
+  #         SYSTEM/
+  #         VENDOR/
+  #         IMAGES/
+  #         <other items extracted from system and vendor target files>
+  #     tools/
+  #         <contents of dexpreopt_tools.zip>
+  #     system_config/
+  #         <contents of system dexpreopt_config.zip>
+  #     vendor_config/
+  #         <contents of vendor dexpreopt_config.zip>
+  #     system -> output/SYSTEM
+  #     vendor -> output/VENDOR
+  #     apex -> output/SYSTEM/apex (only for flattened APEX builds)
+  #     apex/ (extracted updatable APEX)
+  #         <apex 1>/
+  #             ...
+  #         <apex 2>/
+  #             ...
+  #         ...
+  #     out/dex2oat_result/vendor/
+  #         <app>
+  #             oat/arm64/
+  #                 package.vdex
+  #                 package.odex
+  #         <priv-app>
+  #             oat/arm64/
+  #                 package.vdex
+  #                 package.odex
+  dexpreopt_tools_files_temp_dir = os.path.join(temp_dir, 'tools')
+  dexpreopt_framework_config_files_temp_dir = os.path.join(
+      temp_dir, 'system_config')
+  dexpreopt_vendor_config_files_temp_dir = os.path.join(temp_dir,
+                                                        'vendor_config')
+
+  extract_items(
+      input_zip=OPTIONS.framework_dexpreopt_tools,
+      output_dir=dexpreopt_tools_files_temp_dir,
+      extract_item_list=('*',))
+  extract_items(
+      input_zip=OPTIONS.framework_dexpreopt_config,
+      output_dir=dexpreopt_framework_config_files_temp_dir,
+      extract_item_list=('*',))
+  extract_items(
+      input_zip=OPTIONS.vendor_dexpreopt_config,
+      output_dir=dexpreopt_vendor_config_files_temp_dir,
+      extract_item_list=('*',))
+
+  os.symlink(
+      os.path.join(output_target_files_dir, 'SYSTEM'),
+      os.path.join(temp_dir, 'system'))
+  os.symlink(
+      os.path.join(output_target_files_dir, 'VENDOR'),
+      os.path.join(temp_dir, 'vendor'))
+
+  # The directory structure for flatteded APEXes is:
+  #
+  # SYSTEM
+  #     apex
+  #         <APEX name, e.g., com.android.wifi>
+  #             apex_manifest.pb
+  #             apex_pubkey
+  #             etc/
+  #             javalib/
+  #             lib/
+  #             lib64/
+  #             priv-app/
+  #
+  # The directory structure for updatable APEXes is:
+  #
+  # SYSTEM
+  #     apex
+  #         com.android.adbd.apex
+  #         com.android.appsearch.apex
+  #         com.android.art.apex
+  #         ...
+  apex_root = os.path.join(output_target_files_dir, 'SYSTEM', 'apex')
+
+  # Check for flattended versus updatable APEX.
+  if OPTIONS.framework_misc_info.get('target_flatten_apex') == 'false':
+    # Extract APEX.
+    logging.info('extracting APEX')
+
+    apex_extract_root_dir = os.path.join(temp_dir, 'apex')
+    os.makedirs(apex_extract_root_dir)
+
+    for apex in (glob.glob(os.path.join(apex_root, '*.apex')) +
+                 glob.glob(os.path.join(apex_root, '*.capex'))):
+      logging.info('  apex: %s', apex)
+      # deapexer is in the same directory as the merge_target_files binary extracted
+      # from otatools.zip.
+      apex_json_info = subprocess.check_output(['deapexer', 'info', apex])
+      logging.info('    info: %s', apex_json_info)
+      apex_info = json.loads(apex_json_info)
+      apex_name = apex_info['name']
+      logging.info('    name: %s', apex_name)
+
+      apex_extract_dir = os.path.join(apex_extract_root_dir, apex_name)
+      os.makedirs(apex_extract_dir)
+
+      # deapexer uses debugfs_static, which is part of otatools.zip.
+      command = [
+          'deapexer',
+          '--debugfs_path',
+          'debugfs_static',
+          'extract',
+          apex,
+          apex_extract_dir,
+      ]
+      logging.info('    running %s', command)
+      subprocess.check_call(command)
+  else:
+    # Flattened APEXes don't need to be extracted since they have the necessary
+    # directory structure.
+    os.symlink(os.path.join(apex_root), os.path.join(temp_dir, 'apex'))
+
+  # Modify system config to point to the tools that have been extracted.
+  # Absolute or .. paths are not allowed  by the dexpreopt_gen tool in
+  # dexpreopt_soong.config.
+  dexpreopt_framework_soon_config = os.path.join(
+      dexpreopt_framework_config_files_temp_dir, 'dexpreopt_soong.config')
+  with open(dexpreopt_framework_soon_config, 'w') as f:
+    dexpreopt_soong_config = {
+        'Profman': 'tools/profman',
+        'Dex2oat': 'tools/dex2oatd',
+        'Aapt': 'tools/aapt2',
+        'SoongZip': 'tools/soong_zip',
+        'Zip2zip': 'tools/zip2zip',
+        'ManifestCheck': 'tools/manifest_check',
+        'ConstructContext': 'tools/construct_context',
+    }
+    json.dump(dexpreopt_soong_config, f)
+
+  # TODO(b/188179859): Make *dex location configurable to vendor or system_other.
+  use_system_other_odex = False
+
+  if use_system_other_odex:
+    dex_img = 'SYSTEM_OTHER'
+  else:
+    dex_img = 'VENDOR'
+    # Open vendor_filesystem_config to append the items generated by dexopt.
+    vendor_file_system_config = open(
+        os.path.join(temp_dir, 'output', 'META',
+                     'vendor_filesystem_config.txt'), 'a')
+
+  # Dexpreopt vendor apps.
+  dexpreopt_config_suffix = '_dexpreopt.config'
+  for config in glob.glob(
+      os.path.join(dexpreopt_vendor_config_files_temp_dir,
+                   '*' + dexpreopt_config_suffix)):
+    app = os.path.basename(config)[:-len(dexpreopt_config_suffix)]
+    logging.info('dexpreopt config: %s %s', config, app)
+
+    apk_dir = 'app'
+    apk_path = os.path.join(temp_dir, 'vendor', apk_dir, app, app + '.apk')
+    if not os.path.exists(apk_path):
+      apk_dir = 'priv-app'
+      apk_path = os.path.join(temp_dir, 'vendor', apk_dir, app, app + '.apk')
+      if not os.path.exists(apk_path):
+        logging.warning(
+            'skipping dexpreopt for %s, no apk found in vendor/app '
+            'or vendor/priv-app', app)
+        continue
+
+    # Generate dexpreopting script. Note 'out_dir' is not the output directory
+    # where the script is generated, but the OUT_DIR at build time referenced
+    # in the dexpreot config files, e.g., "out/.../core-oj.jar", so the tool knows
+    # how to adjust the path.
+    command = [
+        os.path.join(dexpreopt_tools_files_temp_dir, 'dexpreopt_gen'),
+        '-global',
+        os.path.join(dexpreopt_framework_config_files_temp_dir,
+                     'dexpreopt.config'),
+        '-global_soong',
+        os.path.join(dexpreopt_framework_config_files_temp_dir,
+                     'dexpreopt_soong.config'),
+        '-module',
+        config,
+        '-dexpreopt_script',
+        'dexpreopt_app.sh',
+        '-out_dir',
+        'out',
+        '-base_path',
+        '.',
+        '--uses_target_files',
+    ]
+
+    # Run the command from temp_dir so all tool paths are its descendants.
+    logging.info('running %s', command)
+    subprocess.check_call(command, cwd=temp_dir)
+
+    # Call the generated script.
+    command = ['sh', 'dexpreopt_app.sh', apk_path]
+    logging.info('running %s', command)
+    subprocess.check_call(command, cwd=temp_dir)
+
+    # Output files are in:
+    #
+    # <temp_dir>/out/dex2oat_result/vendor/priv-app/<app>/oat/arm64/package.vdex
+    # <temp_dir>/out/dex2oat_result/vendor/priv-app/<app>/oat/arm64/package.odex
+    # <temp_dir>/out/dex2oat_result/vendor/app/<app>/oat/arm64/package.vdex
+    # <temp_dir>/out/dex2oat_result/vendor/app/<app>/oat/arm64/package.odex
+    #
+    # Copy the files to their destination. The structure of system_other is:
+    #
+    # system_other/
+    #     system-other-odex-marker
+    #     system/
+    #         app/
+    #             <app>/oat/arm64/
+    #                 <app>.odex
+    #                 <app>.vdex
+    #             ...
+    #         priv-app/
+    #             <app>/oat/arm64/
+    #                 <app>.odex
+    #                 <app>.vdex
+    #             ...
+
+    # TODO(b/188179859): Support for other architectures.
+    arch = 'arm64'
+
+    dex_destination = os.path.join(temp_dir, 'output', dex_img, apk_dir, app,
+                                   'oat', arch)
+    os.makedirs(dex_destination)
+    dex2oat_path = os.path.join(temp_dir, 'out', 'dex2oat_result', 'vendor',
+                                apk_dir, app, 'oat', arch)
+    shutil.copy(
+        os.path.join(dex2oat_path, 'package.vdex'),
+        os.path.join(dex_destination, app + '.vdex'))
+    shutil.copy(
+        os.path.join(dex2oat_path, 'package.odex'),
+        os.path.join(dex_destination, app + '.odex'))
+
+    # Append entries to vendor_file_system_config.txt, such as:
+    #
+    # vendor/app/<app>/oat 0 2000 755 selabel=u:object_r:vendor_app_file:s0 capabilities=0x0
+    # vendor/app/<app>/oat/arm64 0 2000 755 selabel=u:object_r:vendor_app_file:s0 capabilities=0x0
+    # vendor/app/<app>/oat/arm64/<app>.odex 0 0 644 selabel=u:object_r:vendor_app_file:s0 capabilities=0x0
+    # vendor/app/<app>/oat/arm64/<app>.vdex 0 0 644 selabel=u:object_r:vendor_app_file:s0 capabilities=0x0
+    if not use_system_other_odex:
+      vendor_app_prefix = 'vendor/' + apk_dir + '/' + app + '/oat'
+      selabel = 'selabel=u:object_r:vendor_app_file:s0 capabilities=0x0'
+      vendor_file_system_config.writelines([
+          vendor_app_prefix + ' 0 2000 755 ' + selabel + '\n',
+          vendor_app_prefix + '/' + arch + ' 0 2000 755 ' + selabel + '\n',
+          vendor_app_prefix + '/' + arch + '/' + app + '.odex 0 0 644 ' +
+          selabel + '\n',
+          vendor_app_prefix + '/' + arch + '/' + app + '.vdex 0 0 644 ' +
+          selabel + '\n',
+      ])
+
+  if not use_system_other_odex:
+    vendor_file_system_config.close()
+    # Delete vendor.img so that it will be regenerated.
+    # TODO(b/188179859): Rebuilding a vendor image in GRF mode (e.g., T(framework)
+    #                    and S(vendor) may require logic similar to that in
+    #                    rebuild_image_with_sepolicy.
+    vendor_img = os.path.join(output_target_files_dir, 'IMAGES', 'vendor.img')
+    if os.path.exists(vendor_img):
+      logging.info('Deleting %s', vendor_img)
+      os.remove(vendor_img)
diff --git a/tools/releasetools/merge/merge_meta.py b/tools/releasetools/merge/merge_meta.py
new file mode 100644
index 0000000..81f6729
--- /dev/null
+++ b/tools/releasetools/merge/merge_meta.py
@@ -0,0 +1,286 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2022 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.
+#
+"""Functions for merging META/* files from partial builds.
+
+Expects items in OPTIONS prepared by merge_target_files.py.
+"""
+
+import logging
+import os
+import re
+import shutil
+
+import build_image
+import common
+import merge_utils
+import sparse_img
+import verity_utils
+
+from common import ExternalError
+
+logger = logging.getLogger(__name__)
+
+OPTIONS = common.OPTIONS
+
+# In apexkeys.txt or apkcerts.txt, we will find partition tags on each entry in
+# the file. We use these partition tags to filter the entries in those files
+# from the two different target files packages to produce a merged apexkeys.txt
+# or apkcerts.txt file. A partition tag (e.g., for the product partition) looks
+# like this: 'partition="product"'. We use the group syntax grab the value of
+# the tag. We use non-greedy matching in case there are other fields on the
+# same line.
+
+PARTITION_TAG_PATTERN = re.compile(r'partition="(.*?)"')
+
+# The sorting algorithm for apexkeys.txt and apkcerts.txt does not include the
+# ".apex" or ".apk" suffix, so we use the following pattern to extract a key.
+
+MODULE_KEY_PATTERN = re.compile(r'name="(.+)\.(apex|apk)"')
+
+
+def MergeMetaFiles(temp_dir, merged_dir):
+  """Merges various files in META/*."""
+
+  framework_meta_dir = os.path.join(temp_dir, 'framework_meta', 'META')
+  merge_utils.ExtractItems(
+      input_zip=OPTIONS.framework_target_files,
+      output_dir=os.path.dirname(framework_meta_dir),
+      extract_item_list=('META/*',))
+
+  vendor_meta_dir = os.path.join(temp_dir, 'vendor_meta', 'META')
+  merge_utils.ExtractItems(
+      input_zip=OPTIONS.vendor_target_files,
+      output_dir=os.path.dirname(vendor_meta_dir),
+      extract_item_list=('META/*',))
+
+  merged_meta_dir = os.path.join(merged_dir, 'META')
+
+  # Merge META/misc_info.txt into OPTIONS.merged_misc_info,
+  # but do not write it yet. The following functions may further
+  # modify this dict.
+  OPTIONS.merged_misc_info = MergeMiscInfo(
+      framework_meta_dir=framework_meta_dir,
+      vendor_meta_dir=vendor_meta_dir,
+      merged_meta_dir=merged_meta_dir)
+
+  CopyNamedFileContexts(
+      framework_meta_dir=framework_meta_dir,
+      vendor_meta_dir=vendor_meta_dir,
+      merged_meta_dir=merged_meta_dir)
+
+  if OPTIONS.merged_misc_info.get('use_dynamic_partitions') == 'true':
+    MergeDynamicPartitionsInfo(
+        framework_meta_dir=framework_meta_dir,
+        vendor_meta_dir=vendor_meta_dir,
+        merged_meta_dir=merged_meta_dir)
+
+  if OPTIONS.merged_misc_info.get('ab_update') == 'true':
+    MergeAbPartitions(
+        framework_meta_dir=framework_meta_dir,
+        vendor_meta_dir=vendor_meta_dir,
+        merged_meta_dir=merged_meta_dir)
+    UpdateCareMapImageSizeProps(images_dir=os.path.join(merged_dir, 'IMAGES'))
+
+  for file_name in ('apkcerts.txt', 'apexkeys.txt'):
+    MergePackageKeys(
+        framework_meta_dir=framework_meta_dir,
+        vendor_meta_dir=vendor_meta_dir,
+        merged_meta_dir=merged_meta_dir,
+        file_name=file_name)
+
+  # Write the now-finalized OPTIONS.merged_misc_info.
+  merge_utils.WriteSortedData(
+      data=OPTIONS.merged_misc_info,
+      path=os.path.join(merged_meta_dir, 'misc_info.txt'))
+
+
+def MergeAbPartitions(framework_meta_dir, vendor_meta_dir, merged_meta_dir):
+  """Merges META/ab_partitions.txt.
+
+  The output contains the union of the partition names.
+  """
+  with open(os.path.join(framework_meta_dir, 'ab_partitions.txt')) as f:
+    framework_ab_partitions = f.read().splitlines()
+
+  with open(os.path.join(vendor_meta_dir, 'ab_partitions.txt')) as f:
+    vendor_ab_partitions = f.read().splitlines()
+
+  merge_utils.WriteSortedData(
+      data=set(framework_ab_partitions + vendor_ab_partitions),
+      path=os.path.join(merged_meta_dir, 'ab_partitions.txt'))
+
+
+def MergeMiscInfo(framework_meta_dir, vendor_meta_dir, merged_meta_dir):
+  """Merges META/misc_info.txt.
+
+  The output contains a combination of key=value pairs from both inputs.
+  Most pairs are taken from the vendor input, while some are taken from
+  the framework input.
+  """
+
+  OPTIONS.framework_misc_info = common.LoadDictionaryFromFile(
+      os.path.join(framework_meta_dir, 'misc_info.txt'))
+  OPTIONS.vendor_misc_info = common.LoadDictionaryFromFile(
+      os.path.join(vendor_meta_dir, 'misc_info.txt'))
+
+  # Merged misc info is a combination of vendor misc info plus certain values
+  # from the framework misc info.
+
+  merged_dict = OPTIONS.vendor_misc_info
+  for key in OPTIONS.framework_misc_info_keys:
+    merged_dict[key] = OPTIONS.framework_misc_info[key]
+
+  # If AVB is enabled then ensure that we build vbmeta.img.
+  # Partial builds with AVB enabled may set PRODUCT_BUILD_VBMETA_IMAGE=false to
+  # skip building an incomplete vbmeta.img.
+  if merged_dict.get('avb_enable') == 'true':
+    merged_dict['avb_building_vbmeta_image'] = 'true'
+
+  return merged_dict
+
+
+def MergeDynamicPartitionsInfo(framework_meta_dir, vendor_meta_dir,
+                               merged_meta_dir):
+  """Merge META/dynamic_partitions_info.txt."""
+  framework_dynamic_partitions_dict = common.LoadDictionaryFromFile(
+      os.path.join(framework_meta_dir, 'dynamic_partitions_info.txt'))
+  vendor_dynamic_partitions_dict = common.LoadDictionaryFromFile(
+      os.path.join(vendor_meta_dir, 'dynamic_partitions_info.txt'))
+
+  merged_dynamic_partitions_dict = common.MergeDynamicPartitionInfoDicts(
+      framework_dict=framework_dynamic_partitions_dict,
+      vendor_dict=vendor_dynamic_partitions_dict)
+
+  merge_utils.WriteSortedData(
+      data=merged_dynamic_partitions_dict,
+      path=os.path.join(merged_meta_dir, 'dynamic_partitions_info.txt'))
+
+  # Merge misc info keys used for Dynamic Partitions.
+  OPTIONS.merged_misc_info.update(merged_dynamic_partitions_dict)
+  # Ensure that add_img_to_target_files rebuilds super split images for
+  # devices that retrofit dynamic partitions. This flag may have been set to
+  # false in the partial builds to prevent duplicate building of super.img.
+  OPTIONS.merged_misc_info['build_super_partition'] = 'true'
+
+
+def MergePackageKeys(framework_meta_dir, vendor_meta_dir, merged_meta_dir,
+                     file_name):
+  """Merges APK/APEX key list files."""
+
+  if file_name not in ('apkcerts.txt', 'apexkeys.txt'):
+    raise ExternalError(
+        'Unexpected file_name provided to merge_package_keys_txt: %s',
+        file_name)
+
+  def read_helper(d):
+    temp = {}
+    with open(os.path.join(d, file_name)) as f:
+      for line in f.read().splitlines():
+        line = line.strip()
+        if line:
+          name_search = MODULE_KEY_PATTERN.search(line.split()[0])
+          temp[name_search.group(1)] = line
+    return temp
+
+  framework_dict = read_helper(framework_meta_dir)
+  vendor_dict = read_helper(vendor_meta_dir)
+  merged_dict = {}
+
+  def filter_into_merged_dict(item_dict, partition_set):
+    for key, value in item_dict.items():
+      tag_search = PARTITION_TAG_PATTERN.search(value)
+
+      if tag_search is None:
+        raise ValueError('Entry missing partition tag: %s' % value)
+
+      partition_tag = tag_search.group(1)
+
+      if partition_tag in partition_set:
+        if key in merged_dict:
+          if OPTIONS.allow_duplicate_apkapex_keys:
+            # TODO(b/150582573) Always raise on duplicates.
+            logger.warning('Duplicate key %s' % key)
+            continue
+          else:
+            raise ValueError('Duplicate key %s' % key)
+
+        merged_dict[key] = value
+
+  # Prioritize framework keys first.
+  # Duplicate keys from vendor are an error, or ignored.
+  filter_into_merged_dict(framework_dict, OPTIONS.framework_partition_set)
+  filter_into_merged_dict(vendor_dict, OPTIONS.vendor_partition_set)
+
+  # The following code is similar to WriteSortedData, but different enough
+  # that we couldn't use that function. We need the output to be sorted by the
+  # basename of the apex/apk (without the ".apex" or ".apk" suffix). This
+  # allows the sort to be consistent with the framework/vendor input data and
+  # eases comparison of input data with merged data.
+  with open(os.path.join(merged_meta_dir, file_name), 'w') as output:
+    for key, value in sorted(merged_dict.items()):
+      output.write(value + '\n')
+
+
+def CopyNamedFileContexts(framework_meta_dir, vendor_meta_dir, merged_meta_dir):
+  """Creates named copies of each partial build's file_contexts.bin.
+
+  Used when regenerating images from the partial build.
+  """
+
+  def copy_fc_file(source_dir, file_name):
+    for name in (file_name, 'file_contexts.bin'):
+      fc_path = os.path.join(source_dir, name)
+      if os.path.exists(fc_path):
+        shutil.copyfile(fc_path, os.path.join(merged_meta_dir, file_name))
+        return
+    raise ValueError('Missing file_contexts file from %s: %s', source_dir,
+                     file_name)
+
+  copy_fc_file(framework_meta_dir, 'framework_file_contexts.bin')
+  copy_fc_file(vendor_meta_dir, 'vendor_file_contexts.bin')
+
+  # Replace <image>_selinux_fc values with framework or vendor file_contexts.bin
+  # depending on which dictionary the key came from.
+  # Only the file basename is required because all selinux_fc properties are
+  # replaced with the full path to the file under META/ when misc_info.txt is
+  # loaded from target files for repacking. See common.py LoadInfoDict().
+  for key in OPTIONS.vendor_misc_info:
+    if key.endswith('_selinux_fc'):
+      OPTIONS.merged_misc_info[key] = 'vendor_file_contexts.bin'
+  for key in OPTIONS.framework_misc_info:
+    if key.endswith('_selinux_fc'):
+      OPTIONS.merged_misc_info[key] = 'framework_file_contexts.bin'
+
+
+def UpdateCareMapImageSizeProps(images_dir):
+  """Sets <partition>_image_size props in misc_info.
+
+  add_images_to_target_files uses these props to generate META/care_map.pb.
+  Regenerated images will have this property set during regeneration.
+
+  However, images copied directly from input partial target files packages
+  need this value calculated here.
+  """
+  for partition in common.PARTITIONS_WITH_CARE_MAP:
+    image_path = os.path.join(images_dir, '{}.img'.format(partition))
+    if os.path.exists(image_path):
+      partition_size = sparse_img.GetImagePartitionSize(image_path)
+      image_props = build_image.ImagePropFromGlobalDict(
+          OPTIONS.merged_misc_info, partition)
+      verity_image_builder = verity_utils.CreateVerityImageBuilder(image_props)
+      image_size = verity_image_builder.CalculateMaxImageSize(partition_size)
+      OPTIONS.merged_misc_info['{}_image_size'.format(partition)] = image_size
diff --git a/tools/releasetools/merge/merge_target_files.py b/tools/releasetools/merge/merge_target_files.py
index 25ed60e..67dd6f1 100755
--- a/tools/releasetools/merge/merge_target_files.py
+++ b/tools/releasetools/merge/merge_target_files.py
@@ -102,29 +102,22 @@
       If provided, the location of vendor's dexpreopt_config.zip.
 """
 
-import fnmatch
-import glob
-import json
 import logging
 import os
-import re
 import shutil
 import subprocess
 import sys
-import zipfile
-from xml.etree import ElementTree
 
 import add_img_to_target_files
-import apex_utils
 import build_image
 import build_super_image
-import check_target_files_vintf
 import common
 import img_from_target_files
-import find_shareduid_violation
+import merge_compatibility_checks
+import merge_dexopt
+import merge_meta
+import merge_utils
 import ota_from_target_files
-import sparse_img
-import verity_utils
 
 from common import ExternalError
 
@@ -154,28 +147,6 @@
 OPTIONS.framework_dexpreopt_tools = None
 OPTIONS.vendor_dexpreopt_config = None
 
-# In an item list (framework or vendor), we may see entries that select whole
-# partitions. Such an entry might look like this 'SYSTEM/*' (e.g., for the
-# system partition). The following regex matches this and extracts the
-# partition name.
-
-PARTITION_ITEM_PATTERN = re.compile(r'^([A-Z_]+)/\*$')
-
-# In apexkeys.txt or apkcerts.txt, we will find partition tags on each entry in
-# the file. We use these partition tags to filter the entries in those files
-# from the two different target files packages to produce a merged apexkeys.txt
-# or apkcerts.txt file. A partition tag (e.g., for the product partition) looks
-# like this: 'partition="product"'. We use the group syntax grab the value of
-# the tag. We use non-greedy matching in case there are other fields on the
-# same line.
-
-PARTITION_TAG_PATTERN = re.compile(r'partition="(.*?)"')
-
-# The sorting algorithm for apexkeys.txt and apkcerts.txt does not include the
-# ".apex" or ".apk" suffix, so we use the following pattern to extract a key.
-
-MODULE_KEY_PATTERN = re.compile(r'name="(.+)\.(apex|apk)"')
-
 # DEFAULT_FRAMEWORK_ITEM_LIST is a list of items to extract from the partial
 # framework target files package as is, meaning these items will land in the
 # output target files package exactly as they appear in the input partial
@@ -234,801 +205,6 @@
     'VENDOR/*',
 )
 
-# The merge config lists should not attempt to extract items from both
-# builds for any of the following partitions. The partitions in
-# SINGLE_BUILD_PARTITIONS should come entirely from a single build (either
-# framework or vendor, but not both).
-
-SINGLE_BUILD_PARTITIONS = (
-    'BOOT/',
-    'DATA/',
-    'ODM/',
-    'PRODUCT/',
-    'SYSTEM_EXT/',
-    'RADIO/',
-    'RECOVERY/',
-    'ROOT/',
-    'SYSTEM/',
-    'SYSTEM_OTHER/',
-    'VENDOR/',
-    'VENDOR_DLKM/',
-    'ODM_DLKM/',
-    'SYSTEM_DLKM/',
-)
-
-
-def write_sorted_data(data, path):
-  """Writes the sorted contents of either a list or dict to file.
-
-  This function sorts the contents of the list or dict and then writes the
-  resulting sorted contents to a file specified by path.
-
-  Args:
-    data: The list or dict to sort and write.
-    path: Path to the file to write the sorted values to. The file at path will
-      be overridden if it exists.
-  """
-  with open(path, 'w') as output:
-    for entry in sorted(data):
-      out_str = '{}={}\n'.format(entry, data[entry]) if isinstance(
-          data, dict) else '{}\n'.format(entry)
-      output.write(out_str)
-
-
-def extract_items(input_zip, output_dir, extract_item_list):
-  """Extracts items in extra_item_list from a zip to a dir."""
-
-  logger.info('extracting from %s', input_zip)
-
-  # Filter the extract_item_list to remove any items that do not exist in the
-  # zip file. Otherwise, the extraction step will fail.
-
-  with zipfile.ZipFile(input_zip, allowZip64=True) as input_zipfile:
-    input_namelist = input_zipfile.namelist()
-
-  filtered_extract_item_list = []
-  for pattern in extract_item_list:
-    matching_namelist = fnmatch.filter(input_namelist, pattern)
-    if not matching_namelist:
-      logger.warning('no match for %s', pattern)
-    else:
-      filtered_extract_item_list.append(pattern)
-
-  common.UnzipToDir(input_zip, output_dir, filtered_extract_item_list)
-
-
-def copy_items(from_dir, to_dir, patterns):
-  """Similar to extract_items() except uses an input dir instead of zip."""
-  file_paths = []
-  for dirpath, _, filenames in os.walk(from_dir):
-    file_paths.extend(
-        os.path.relpath(path=os.path.join(dirpath, filename), start=from_dir)
-        for filename in filenames)
-
-  filtered_file_paths = set()
-  for pattern in patterns:
-    filtered_file_paths.update(fnmatch.filter(file_paths, pattern))
-
-  for file_path in filtered_file_paths:
-    original_file_path = os.path.join(from_dir, file_path)
-    copied_file_path = os.path.join(to_dir, file_path)
-    copied_file_dir = os.path.dirname(copied_file_path)
-    if not os.path.exists(copied_file_dir):
-      os.makedirs(copied_file_dir)
-    if os.path.islink(original_file_path):
-      os.symlink(os.readlink(original_file_path), copied_file_path)
-    else:
-      shutil.copyfile(original_file_path, copied_file_path)
-
-
-def validate_config_lists():
-  """Performs validations on the merge config lists.
-
-  Returns:
-    False if a validation fails, otherwise true.
-  """
-  has_error = False
-
-  default_combined_item_set = set(DEFAULT_FRAMEWORK_ITEM_LIST)
-  default_combined_item_set.update(DEFAULT_VENDOR_ITEM_LIST)
-
-  combined_item_set = set(OPTIONS.framework_item_list)
-  combined_item_set.update(OPTIONS.vendor_item_list)
-
-  # Check that the merge config lists are not missing any item specified
-  # by the default config lists.
-  difference = default_combined_item_set.difference(combined_item_set)
-  if difference:
-    logger.error('Missing merge config items: %s', list(difference))
-    logger.error('Please ensure missing items are in either the '
-                 'framework-item-list or vendor-item-list files provided to '
-                 'this script.')
-    has_error = True
-
-  # Check that partitions only come from one input.
-  for partition in SINGLE_BUILD_PARTITIONS:
-    image_path = 'IMAGES/{}.img'.format(partition.lower().replace('/', ''))
-    in_framework = (
-        any(item.startswith(partition) for item in OPTIONS.framework_item_list)
-        or image_path in OPTIONS.framework_item_list)
-    in_vendor = (
-        any(item.startswith(partition) for item in OPTIONS.vendor_item_list) or
-        image_path in OPTIONS.vendor_item_list)
-    if in_framework and in_vendor:
-      logger.error(
-          'Cannot extract items from %s for both the framework and vendor'
-          ' builds. Please ensure only one merge config item list'
-          ' includes %s.', partition, partition)
-      has_error = True
-
-  if ('dynamic_partition_list' in OPTIONS.framework_misc_info_keys) or (
-      'super_partition_groups' in OPTIONS.framework_misc_info_keys):
-    logger.error('Dynamic partition misc info keys should come from '
-                 'the vendor instance of META/misc_info.txt.')
-    has_error = True
-
-  return not has_error
-
-
-def merge_ab_partitions_txt(framework_meta_dir, vendor_meta_dir,
-                            merged_meta_dir):
-  """Merges META/ab_partitions.txt.
-
-  The output contains the union of the partition names.
-  """
-  with open(os.path.join(framework_meta_dir, 'ab_partitions.txt')) as f:
-    framework_ab_partitions = f.read().splitlines()
-
-  with open(os.path.join(vendor_meta_dir, 'ab_partitions.txt')) as f:
-    vendor_ab_partitions = f.read().splitlines()
-
-  write_sorted_data(
-      data=set(framework_ab_partitions + vendor_ab_partitions),
-      path=os.path.join(merged_meta_dir, 'ab_partitions.txt'))
-
-
-def merge_misc_info_txt(framework_meta_dir, vendor_meta_dir, merged_meta_dir):
-  """Merges META/misc_info.txt.
-
-  The output contains a combination of key=value pairs from both inputs.
-  Most pairs are taken from the vendor input, while some are taken from
-  the framework input.
-  """
-
-  OPTIONS.framework_misc_info = common.LoadDictionaryFromFile(
-      os.path.join(framework_meta_dir, 'misc_info.txt'))
-  OPTIONS.vendor_misc_info = common.LoadDictionaryFromFile(
-      os.path.join(vendor_meta_dir, 'misc_info.txt'))
-
-  # Merged misc info is a combination of vendor misc info plus certain values
-  # from the framework misc info.
-
-  merged_dict = OPTIONS.vendor_misc_info
-  for key in OPTIONS.framework_misc_info_keys:
-    merged_dict[key] = OPTIONS.framework_misc_info[key]
-
-  # If AVB is enabled then ensure that we build vbmeta.img.
-  # Partial builds with AVB enabled may set PRODUCT_BUILD_VBMETA_IMAGE=false to
-  # skip building an incomplete vbmeta.img.
-  if merged_dict.get('avb_enable') == 'true':
-    merged_dict['avb_building_vbmeta_image'] = 'true'
-
-  return merged_dict
-
-
-def merge_dynamic_partitions_info_txt(framework_meta_dir, vendor_meta_dir,
-                                      merged_meta_dir):
-  """Merge META/dynamic_partitions_info.txt."""
-  framework_dynamic_partitions_dict = common.LoadDictionaryFromFile(
-      os.path.join(framework_meta_dir, 'dynamic_partitions_info.txt'))
-  vendor_dynamic_partitions_dict = common.LoadDictionaryFromFile(
-      os.path.join(vendor_meta_dir, 'dynamic_partitions_info.txt'))
-
-  merged_dynamic_partitions_dict = common.MergeDynamicPartitionInfoDicts(
-      framework_dict=framework_dynamic_partitions_dict,
-      vendor_dict=vendor_dynamic_partitions_dict)
-
-  write_sorted_data(
-      data=merged_dynamic_partitions_dict,
-      path=os.path.join(merged_meta_dir, 'dynamic_partitions_info.txt'))
-
-  # Merge misc info keys used for Dynamic Partitions.
-  OPTIONS.merged_misc_info.update(merged_dynamic_partitions_dict)
-  # Ensure that add_img_to_target_files rebuilds super split images for
-  # devices that retrofit dynamic partitions. This flag may have been set to
-  # false in the partial builds to prevent duplicate building of super.img.
-  OPTIONS.merged_misc_info['build_super_partition'] = 'true'
-
-
-def item_list_to_partition_set(item_list):
-  """Converts a target files item list to a partition set.
-
-  The item list contains items that might look like 'SYSTEM/*' or 'VENDOR/*' or
-  'OTA/android-info.txt'. Items that end in '/*' are assumed to match entire
-  directories where 'SYSTEM' or 'VENDOR' is a directory name that identifies the
-  contents of a partition of the same name. Other items in the list, such as the
-  'OTA' example contain metadata. This function iterates such a list, returning
-  a set that contains the partition entries.
-
-  Args:
-    item_list: A list of items in a target files package.
-
-  Returns:
-    A set of partitions extracted from the list of items.
-  """
-
-  partition_set = set()
-
-  for item in item_list:
-    match = PARTITION_ITEM_PATTERN.search(item.strip())
-    partition_tag = match.group(1).lower() if match else None
-
-    if partition_tag:
-      partition_set.add(partition_tag)
-
-  return partition_set
-
-
-def merge_package_keys_txt(framework_meta_dir, vendor_meta_dir, merged_meta_dir,
-                           file_name):
-  """Merges APK/APEX key list files."""
-
-  if file_name not in ('apkcerts.txt', 'apexkeys.txt'):
-    raise ExternalError(
-        'Unexpected file_name provided to merge_package_keys_txt: %s',
-        file_name)
-
-  def read_helper(d):
-    temp = {}
-    with open(os.path.join(d, file_name)) as f:
-      for line in f.read().splitlines():
-        line = line.strip()
-        if line:
-          name_search = MODULE_KEY_PATTERN.search(line.split()[0])
-          temp[name_search.group(1)] = line
-    return temp
-
-  framework_dict = read_helper(framework_meta_dir)
-  vendor_dict = read_helper(vendor_meta_dir)
-  merged_dict = {}
-
-  def filter_into_merged_dict(item_dict, partition_set):
-    for key, value in item_dict.items():
-      tag_search = PARTITION_TAG_PATTERN.search(value)
-
-      if tag_search is None:
-        raise ValueError('Entry missing partition tag: %s' % value)
-
-      partition_tag = tag_search.group(1)
-
-      if partition_tag in partition_set:
-        if key in merged_dict:
-          if OPTIONS.allow_duplicate_apkapex_keys:
-            # TODO(b/150582573) Always raise on duplicates.
-            logger.warning('Duplicate key %s' % key)
-            continue
-          else:
-            raise ValueError('Duplicate key %s' % key)
-
-        merged_dict[key] = value
-
-  # Prioritize framework keys first.
-  # Duplicate keys from vendor are an error, or ignored.
-  filter_into_merged_dict(framework_dict, OPTIONS.framework_partition_set)
-  filter_into_merged_dict(vendor_dict, OPTIONS.vendor_partition_set)
-
-  # The following code is similar to write_sorted_data, but different enough
-  # that we couldn't use that function. We need the output to be sorted by the
-  # basename of the apex/apk (without the ".apex" or ".apk" suffix). This
-  # allows the sort to be consistent with the framework/vendor input data and
-  # eases comparison of input data with merged data.
-  with open(os.path.join(merged_meta_dir, file_name), 'w') as output:
-    for key, value in sorted(merged_dict.items()):
-      output.write(value + '\n')
-
-
-def create_file_contexts_copies(framework_meta_dir, vendor_meta_dir,
-                                merged_meta_dir):
-  """Creates named copies of each partial build's file_contexts.bin.
-
-  Used when regenerating images from the partial build.
-  """
-
-  def copy_fc_file(source_dir, file_name):
-    for name in (file_name, 'file_contexts.bin'):
-      fc_path = os.path.join(source_dir, name)
-      if os.path.exists(fc_path):
-        shutil.copyfile(fc_path, os.path.join(merged_meta_dir, file_name))
-        return
-    raise ValueError('Missing file_contexts file from %s: %s', source_dir,
-                     file_name)
-
-  copy_fc_file(framework_meta_dir, 'framework_file_contexts.bin')
-  copy_fc_file(vendor_meta_dir, 'vendor_file_contexts.bin')
-
-  # Replace <image>_selinux_fc values with framework or vendor file_contexts.bin
-  # depending on which dictionary the key came from.
-  # Only the file basename is required because all selinux_fc properties are
-  # replaced with the full path to the file under META/ when misc_info.txt is
-  # loaded from target files for repacking. See common.py LoadInfoDict().
-  for key in OPTIONS.vendor_misc_info:
-    if key.endswith('_selinux_fc'):
-      OPTIONS.merged_misc_info[key] = 'vendor_file_contexts.bin'
-  for key in OPTIONS.framework_misc_info:
-    if key.endswith('_selinux_fc'):
-      OPTIONS.merged_misc_info[key] = 'framework_file_contexts.bin'
-
-
-def compile_split_sepolicy(target_files_dir, partition_map):
-  """Uses secilc to compile a split sepolicy file.
-
-  Depends on various */etc/selinux/* and */etc/vintf/* files within partitions.
-
-  Args:
-    target_files_dir: Extracted directory of target_files, containing partition
-      directories.
-    partition_map: A map of partition name -> relative path within
-      target_files_dir.
-
-  Returns:
-    A command list that can be executed to create the compiled sepolicy.
-  """
-
-  def get_file(partition, path):
-    if partition not in partition_map:
-      logger.warning('Cannot load SEPolicy files for missing partition %s',
-                     partition)
-      return None
-    return os.path.join(target_files_dir, partition_map[partition], path)
-
-  # Load the kernel sepolicy version from the FCM. This is normally provided
-  # directly to selinux.cpp as a build flag, but is also available in this file.
-  fcm_file = get_file('system', 'etc/vintf/compatibility_matrix.device.xml')
-  if not fcm_file or not os.path.exists(fcm_file):
-    raise ExternalError('Missing required file for loading sepolicy: %s', fcm)
-  kernel_sepolicy_version = ElementTree.parse(fcm_file).getroot().find(
-      'sepolicy/kernel-sepolicy-version').text
-
-  # Load the vendor's plat sepolicy version. This is the version used for
-  # locating sepolicy mapping files.
-  vendor_plat_version_file = get_file('vendor',
-                                      'etc/selinux/plat_sepolicy_vers.txt')
-  if not vendor_plat_version_file or not os.path.exists(
-      vendor_plat_version_file):
-    raise ExternalError('Missing required sepolicy file %s',
-                        vendor_plat_version_file)
-  with open(vendor_plat_version_file) as f:
-    vendor_plat_version = f.read().strip()
-
-  # Use the same flags and arguments as selinux.cpp OpenSplitPolicy().
-  cmd = ['secilc', '-m', '-M', 'true', '-G', '-N']
-  cmd.extend(['-c', kernel_sepolicy_version])
-  cmd.extend(['-o', os.path.join(target_files_dir, 'META/combined_sepolicy')])
-  cmd.extend(['-f', '/dev/null'])
-
-  required_policy_files = (
-      ('system', 'etc/selinux/plat_sepolicy.cil'),
-      ('system', 'etc/selinux/mapping/%s.cil' % vendor_plat_version),
-      ('vendor', 'etc/selinux/vendor_sepolicy.cil'),
-      ('vendor', 'etc/selinux/plat_pub_versioned.cil'),
-  )
-  for policy in (map(lambda partition_and_path: get_file(*partition_and_path),
-                     required_policy_files)):
-    if not policy or not os.path.exists(policy):
-      raise ExternalError('Missing required sepolicy file %s', policy)
-    cmd.append(policy)
-
-  optional_policy_files = (
-      ('system', 'etc/selinux/mapping/%s.compat.cil' % vendor_plat_version),
-      ('system_ext', 'etc/selinux/system_ext_sepolicy.cil'),
-      ('system_ext', 'etc/selinux/mapping/%s.cil' % vendor_plat_version),
-      ('product', 'etc/selinux/product_sepolicy.cil'),
-      ('product', 'etc/selinux/mapping/%s.cil' % vendor_plat_version),
-      ('odm', 'etc/selinux/odm_sepolicy.cil'),
-  )
-  for policy in (map(lambda partition_and_path: get_file(*partition_and_path),
-                     optional_policy_files)):
-    if policy and os.path.exists(policy):
-      cmd.append(policy)
-
-  return cmd
-
-
-def validate_merged_apex_info(target_files_dir, partitions):
-  """Validates the APEX files in the merged target files directory.
-
-  Checks the APEX files in all possible preinstalled APEX directories.
-  Depends on the <partition>/apex/* APEX files within partitions.
-
-  Args:
-    target_files_dir: Extracted directory of target_files, containing partition
-      directories.
-    partitions: A list of all the partitions in the output directory.
-
-  Raises:
-    RuntimeError: if apex_utils fails to parse any APEX file.
-    ExternalError: if the same APEX package is provided by multiple partitions.
-  """
-  apex_packages = set()
-
-  apex_partitions = ('system', 'system_ext', 'product', 'vendor', 'odm')
-  for partition in filter(lambda p: p in apex_partitions, partitions):
-    apex_info = apex_utils.GetApexInfoFromTargetFiles(
-        target_files_dir, partition, compressed_only=False)
-    partition_apex_packages = set([info.package_name for info in apex_info])
-    duplicates = apex_packages.intersection(partition_apex_packages)
-    if duplicates:
-      raise ExternalError(
-          'Duplicate APEX packages found in multiple partitions: %s' %
-          ' '.join(duplicates))
-    apex_packages.update(partition_apex_packages)
-
-
-def update_care_map_image_size_props(images_dir):
-  """Sets <partition>_image_size props in misc_info.
-
-  add_images_to_target_files uses these props to generate META/care_map.pb.
-  Regenerated images will have this property set during regeneration.
-
-  However, images copied directly from input partial target files packages
-  need this value calculated here.
-  """
-  for partition in common.PARTITIONS_WITH_CARE_MAP:
-    image_path = os.path.join(images_dir, '{}.img'.format(partition))
-    if os.path.exists(image_path):
-      partition_size = sparse_img.GetImagePartitionSize(image_path)
-      image_props = build_image.ImagePropFromGlobalDict(
-          OPTIONS.merged_misc_info, partition)
-      verity_image_builder = verity_utils.CreateVerityImageBuilder(image_props)
-      image_size = verity_image_builder.CalculateMaxImageSize(partition_size)
-      OPTIONS.merged_misc_info['{}_image_size'.format(partition)] = image_size
-
-
-def merge_meta_files(temp_dir, merged_dir):
-  """Merges various files in META/*."""
-
-  framework_meta_dir = os.path.join(temp_dir, 'framework_meta', 'META')
-  extract_items(
-      input_zip=OPTIONS.framework_target_files,
-      output_dir=os.path.dirname(framework_meta_dir),
-      extract_item_list=('META/*',))
-
-  vendor_meta_dir = os.path.join(temp_dir, 'vendor_meta', 'META')
-  extract_items(
-      input_zip=OPTIONS.vendor_target_files,
-      output_dir=os.path.dirname(vendor_meta_dir),
-      extract_item_list=('META/*',))
-
-  merged_meta_dir = os.path.join(merged_dir, 'META')
-
-  # Merge META/misc_info.txt into OPTIONS.merged_misc_info,
-  # but do not write it yet. The following functions may further
-  # modify this dict.
-  OPTIONS.merged_misc_info = merge_misc_info_txt(
-      framework_meta_dir=framework_meta_dir,
-      vendor_meta_dir=vendor_meta_dir,
-      merged_meta_dir=merged_meta_dir)
-
-  create_file_contexts_copies(
-      framework_meta_dir=framework_meta_dir,
-      vendor_meta_dir=vendor_meta_dir,
-      merged_meta_dir=merged_meta_dir)
-
-  if OPTIONS.merged_misc_info.get('use_dynamic_partitions') == 'true':
-    merge_dynamic_partitions_info_txt(
-        framework_meta_dir=framework_meta_dir,
-        vendor_meta_dir=vendor_meta_dir,
-        merged_meta_dir=merged_meta_dir)
-
-  if OPTIONS.merged_misc_info.get('ab_update') == 'true':
-    merge_ab_partitions_txt(
-        framework_meta_dir=framework_meta_dir,
-        vendor_meta_dir=vendor_meta_dir,
-        merged_meta_dir=merged_meta_dir)
-    update_care_map_image_size_props(images_dir=os.path.join(merged_dir, 'IMAGES'))
-
-  for file_name in ('apkcerts.txt', 'apexkeys.txt'):
-    merge_package_keys_txt(
-        framework_meta_dir=framework_meta_dir,
-        vendor_meta_dir=vendor_meta_dir,
-        merged_meta_dir=merged_meta_dir,
-        file_name=file_name)
-
-  # Write the now-finalized OPTIONS.merged_misc_info.
-  write_sorted_data(
-      data=OPTIONS.merged_misc_info,
-      path=os.path.join(merged_meta_dir, 'misc_info.txt'))
-
-
-def process_dexopt(temp_dir, output_target_files_dir):
-  """If needed, generates dexopt files for vendor apps.
-
-  Args:
-    temp_dir: Location containing an 'output' directory where target files have
-      been extracted, e.g. <temp_dir>/output/SYSTEM, <temp_dir>/output/IMAGES,
-      etc.
-    output_target_files_dir: The name of a directory that will be used to create
-      the output target files package after all the special cases are processed.
-  """
-  # Load vendor and framework META/misc_info.txt.
-  if (OPTIONS.vendor_misc_info.get('building_with_vsdk') != 'true' or
-      OPTIONS.framework_dexpreopt_tools is None or
-      OPTIONS.framework_dexpreopt_config is None or
-      OPTIONS.vendor_dexpreopt_config is None):
-    return
-
-  logger.info('applying dexpreopt')
-
-  # The directory structure to apply dexpreopt is:
-  #
-  # <temp_dir>/
-  #     framework_meta/
-  #         META/
-  #     vendor_meta/
-  #         META/
-  #     output/
-  #         SYSTEM/
-  #         VENDOR/
-  #         IMAGES/
-  #         <other items extracted from system and vendor target files>
-  #     tools/
-  #         <contents of dexpreopt_tools.zip>
-  #     system_config/
-  #         <contents of system dexpreopt_config.zip>
-  #     vendor_config/
-  #         <contents of vendor dexpreopt_config.zip>
-  #     system -> output/SYSTEM
-  #     vendor -> output/VENDOR
-  #     apex -> output/SYSTEM/apex (only for flattened APEX builds)
-  #     apex/ (extracted updatable APEX)
-  #         <apex 1>/
-  #             ...
-  #         <apex 2>/
-  #             ...
-  #         ...
-  #     out/dex2oat_result/vendor/
-  #         <app>
-  #             oat/arm64/
-  #                 package.vdex
-  #                 package.odex
-  #         <priv-app>
-  #             oat/arm64/
-  #                 package.vdex
-  #                 package.odex
-  dexpreopt_tools_files_temp_dir = os.path.join(temp_dir, 'tools')
-  dexpreopt_framework_config_files_temp_dir = os.path.join(
-      temp_dir, 'system_config')
-  dexpreopt_vendor_config_files_temp_dir = os.path.join(temp_dir,
-                                                        'vendor_config')
-
-  extract_items(
-      input_zip=OPTIONS.framework_dexpreopt_tools,
-      output_dir=dexpreopt_tools_files_temp_dir,
-      extract_item_list=('*',))
-  extract_items(
-      input_zip=OPTIONS.framework_dexpreopt_config,
-      output_dir=dexpreopt_framework_config_files_temp_dir,
-      extract_item_list=('*',))
-  extract_items(
-      input_zip=OPTIONS.vendor_dexpreopt_config,
-      output_dir=dexpreopt_vendor_config_files_temp_dir,
-      extract_item_list=('*',))
-
-  os.symlink(
-      os.path.join(output_target_files_dir, 'SYSTEM'),
-      os.path.join(temp_dir, 'system'))
-  os.symlink(
-      os.path.join(output_target_files_dir, 'VENDOR'),
-      os.path.join(temp_dir, 'vendor'))
-
-  # The directory structure for flatteded APEXes is:
-  #
-  # SYSTEM
-  #     apex
-  #         <APEX name, e.g., com.android.wifi>
-  #             apex_manifest.pb
-  #             apex_pubkey
-  #             etc/
-  #             javalib/
-  #             lib/
-  #             lib64/
-  #             priv-app/
-  #
-  # The directory structure for updatable APEXes is:
-  #
-  # SYSTEM
-  #     apex
-  #         com.android.adbd.apex
-  #         com.android.appsearch.apex
-  #         com.android.art.apex
-  #         ...
-  apex_root = os.path.join(output_target_files_dir, 'SYSTEM', 'apex')
-
-  # Check for flattended versus updatable APEX.
-  if OPTIONS.framework_misc_info.get('target_flatten_apex') == 'false':
-    # Extract APEX.
-    logging.info('extracting APEX')
-
-    apex_extract_root_dir = os.path.join(temp_dir, 'apex')
-    os.makedirs(apex_extract_root_dir)
-
-    for apex in (glob.glob(os.path.join(apex_root, '*.apex')) +
-                 glob.glob(os.path.join(apex_root, '*.capex'))):
-      logging.info('  apex: %s', apex)
-      # deapexer is in the same directory as the merge_target_files binary extracted
-      # from otatools.zip.
-      apex_json_info = subprocess.check_output(['deapexer', 'info', apex])
-      logging.info('    info: %s', apex_json_info)
-      apex_info = json.loads(apex_json_info)
-      apex_name = apex_info['name']
-      logging.info('    name: %s', apex_name)
-
-      apex_extract_dir = os.path.join(apex_extract_root_dir, apex_name)
-      os.makedirs(apex_extract_dir)
-
-      # deapexer uses debugfs_static, which is part of otatools.zip.
-      command = [
-          'deapexer',
-          '--debugfs_path',
-          'debugfs_static',
-          'extract',
-          apex,
-          apex_extract_dir,
-      ]
-      logging.info('    running %s', command)
-      subprocess.check_call(command)
-  else:
-    # Flattened APEXes don't need to be extracted since they have the necessary
-    # directory structure.
-    os.symlink(os.path.join(apex_root), os.path.join(temp_dir, 'apex'))
-
-  # Modify system config to point to the tools that have been extracted.
-  # Absolute or .. paths are not allowed  by the dexpreopt_gen tool in
-  # dexpreopt_soong.config.
-  dexpreopt_framework_soon_config = os.path.join(
-      dexpreopt_framework_config_files_temp_dir, 'dexpreopt_soong.config')
-  with open(dexpreopt_framework_soon_config, 'w') as f:
-    dexpreopt_soong_config = {
-        'Profman': 'tools/profman',
-        'Dex2oat': 'tools/dex2oatd',
-        'Aapt': 'tools/aapt2',
-        'SoongZip': 'tools/soong_zip',
-        'Zip2zip': 'tools/zip2zip',
-        'ManifestCheck': 'tools/manifest_check',
-        'ConstructContext': 'tools/construct_context',
-    }
-    json.dump(dexpreopt_soong_config, f)
-
-  # TODO(b/188179859): Make *dex location configurable to vendor or system_other.
-  use_system_other_odex = False
-
-  if use_system_other_odex:
-    dex_img = 'SYSTEM_OTHER'
-  else:
-    dex_img = 'VENDOR'
-    # Open vendor_filesystem_config to append the items generated by dexopt.
-    vendor_file_system_config = open(
-        os.path.join(temp_dir, 'output', 'META',
-                     'vendor_filesystem_config.txt'), 'a')
-
-  # Dexpreopt vendor apps.
-  dexpreopt_config_suffix = '_dexpreopt.config'
-  for config in glob.glob(
-      os.path.join(dexpreopt_vendor_config_files_temp_dir,
-                   '*' + dexpreopt_config_suffix)):
-    app = os.path.basename(config)[:-len(dexpreopt_config_suffix)]
-    logging.info('dexpreopt config: %s %s', config, app)
-
-    apk_dir = 'app'
-    apk_path = os.path.join(temp_dir, 'vendor', apk_dir, app, app + '.apk')
-    if not os.path.exists(apk_path):
-      apk_dir = 'priv-app'
-      apk_path = os.path.join(temp_dir, 'vendor', apk_dir, app, app + '.apk')
-      if not os.path.exists(apk_path):
-        logging.warning(
-            'skipping dexpreopt for %s, no apk found in vendor/app '
-            'or vendor/priv-app', app)
-        continue
-
-    # Generate dexpreopting script. Note 'out_dir' is not the output directory
-    # where the script is generated, but the OUT_DIR at build time referenced
-    # in the dexpreot config files, e.g., "out/.../core-oj.jar", so the tool knows
-    # how to adjust the path.
-    command = [
-        os.path.join(dexpreopt_tools_files_temp_dir, 'dexpreopt_gen'),
-        '-global',
-        os.path.join(dexpreopt_framework_config_files_temp_dir,
-                     'dexpreopt.config'),
-        '-global_soong',
-        os.path.join(dexpreopt_framework_config_files_temp_dir,
-                     'dexpreopt_soong.config'),
-        '-module',
-        config,
-        '-dexpreopt_script',
-        'dexpreopt_app.sh',
-        '-out_dir',
-        'out',
-        '-base_path',
-        '.',
-        '--uses_target_files',
-    ]
-
-    # Run the command from temp_dir so all tool paths are its descendants.
-    logging.info('running %s', command)
-    subprocess.check_call(command, cwd=temp_dir)
-
-    # Call the generated script.
-    command = ['sh', 'dexpreopt_app.sh', apk_path]
-    logging.info('running %s', command)
-    subprocess.check_call(command, cwd=temp_dir)
-
-    # Output files are in:
-    #
-    # <temp_dir>/out/dex2oat_result/vendor/priv-app/<app>/oat/arm64/package.vdex
-    # <temp_dir>/out/dex2oat_result/vendor/priv-app/<app>/oat/arm64/package.odex
-    # <temp_dir>/out/dex2oat_result/vendor/app/<app>/oat/arm64/package.vdex
-    # <temp_dir>/out/dex2oat_result/vendor/app/<app>/oat/arm64/package.odex
-    #
-    # Copy the files to their destination. The structure of system_other is:
-    #
-    # system_other/
-    #     system-other-odex-marker
-    #     system/
-    #         app/
-    #             <app>/oat/arm64/
-    #                 <app>.odex
-    #                 <app>.vdex
-    #             ...
-    #         priv-app/
-    #             <app>/oat/arm64/
-    #                 <app>.odex
-    #                 <app>.vdex
-    #             ...
-
-    # TODO(b/188179859): Support for other architectures.
-    arch = 'arm64'
-
-    dex_destination = os.path.join(temp_dir, 'output', dex_img, apk_dir, app,
-                                   'oat', arch)
-    os.makedirs(dex_destination)
-    dex2oat_path = os.path.join(temp_dir, 'out', 'dex2oat_result', 'vendor',
-                                apk_dir, app, 'oat', arch)
-    shutil.copy(
-        os.path.join(dex2oat_path, 'package.vdex'),
-        os.path.join(dex_destination, app + '.vdex'))
-    shutil.copy(
-        os.path.join(dex2oat_path, 'package.odex'),
-        os.path.join(dex_destination, app + '.odex'))
-
-    # Append entries to vendor_file_system_config.txt, such as:
-    #
-    # vendor/app/<app>/oat 0 2000 755 selabel=u:object_r:vendor_app_file:s0 capabilities=0x0
-    # vendor/app/<app>/oat/arm64 0 2000 755 selabel=u:object_r:vendor_app_file:s0 capabilities=0x0
-    # vendor/app/<app>/oat/arm64/<app>.odex 0 0 644 selabel=u:object_r:vendor_app_file:s0 capabilities=0x0
-    # vendor/app/<app>/oat/arm64/<app>.vdex 0 0 644 selabel=u:object_r:vendor_app_file:s0 capabilities=0x0
-    if not use_system_other_odex:
-      vendor_app_prefix = 'vendor/' + apk_dir + '/' + app + '/oat'
-      selabel = 'selabel=u:object_r:vendor_app_file:s0 capabilities=0x0'
-      vendor_file_system_config.writelines([
-          vendor_app_prefix + ' 0 2000 755 ' + selabel + '\n',
-          vendor_app_prefix + '/' + arch + ' 0 2000 755 ' + selabel + '\n',
-          vendor_app_prefix + '/' + arch + '/' + app + '.odex 0 0 644 ' +
-          selabel + '\n',
-          vendor_app_prefix + '/' + arch + '/' + app + '.vdex 0 0 644 ' +
-          selabel + '\n',
-      ])
-
-  if not use_system_other_odex:
-    vendor_file_system_config.close()
-    # Delete vendor.img so that it will be regenerated.
-    # TODO(b/188179859): Rebuilding a vendor image in GRF mode (e.g., T(framework)
-    #                    and S(vendor) may require logic similar to that in
-    #                    rebuild_image_with_sepolicy.
-    vendor_img = os.path.join(output_target_files_dir, 'IMAGES', 'vendor.img')
-    if os.path.exists(vendor_img):
-      logging.info('Deleting %s', vendor_img)
-      os.remove(vendor_img)
-
 
 def create_merged_package(temp_dir):
   """Merges two target files packages into one target files structure.
@@ -1041,11 +217,11 @@
   # do not need special case processing.
 
   output_target_files_temp_dir = os.path.join(temp_dir, 'output')
-  extract_items(
+  merge_utils.ExtractItems(
       input_zip=OPTIONS.framework_target_files,
       output_dir=output_target_files_temp_dir,
       extract_item_list=OPTIONS.framework_item_list)
-  extract_items(
+  merge_utils.ExtractItems(
       input_zip=OPTIONS.vendor_target_files,
       output_dir=output_target_files_temp_dir,
       extract_item_list=OPTIONS.vendor_item_list)
@@ -1053,9 +229,10 @@
   # Perform special case processing on META/* items.
   # After this function completes successfully, all the files we need to create
   # the output target files package are in place.
-  merge_meta_files(temp_dir=temp_dir, merged_dir=output_target_files_temp_dir)
+  merge_meta.MergeMetaFiles(
+      temp_dir=temp_dir, merged_dir=output_target_files_temp_dir)
 
-  process_dexopt(
+  merge_dexopt.MergeDexopt(
       temp_dir=temp_dir, output_target_files_dir=output_target_files_temp_dir)
 
   return output_target_files_temp_dir
@@ -1284,58 +461,22 @@
 
   output_target_files_temp_dir = create_merged_package(temp_dir)
 
-  if not check_target_files_vintf.CheckVintf(output_target_files_temp_dir):
-    raise RuntimeError('Incompatible VINTF metadata')
-
   partition_map = common.PartitionMapFromTargetFiles(
       output_target_files_temp_dir)
 
-  # Generate and check for cross-partition violations of sharedUserId
-  # values in APKs. This requires the input target-files packages to contain
-  # *.apk files.
-  shareduid_violation_modules = os.path.join(
-      output_target_files_temp_dir, 'META', 'shareduid_violation_modules.json')
-  with open(shareduid_violation_modules, 'w') as f:
-    violation = find_shareduid_violation.FindShareduidViolation(
-        output_target_files_temp_dir, partition_map)
+  compatibility_errors = merge_compatibility_checks.CheckCompatibility(
+      target_files_dir=output_target_files_temp_dir,
+      partition_map=partition_map)
+  if compatibility_errors:
+    for error in compatibility_errors:
+      logger.error(error)
+    raise ExternalError(
+        'Found incompatibilities in the merged target files package.')
 
-    # Write the output to a file to enable debugging.
-    f.write(violation)
-
-    # Check for violations across the input builds' partition groups.
-    shareduid_errors = common.SharedUidPartitionViolations(
-        json.loads(violation),
-        [OPTIONS.framework_partition_set, OPTIONS.vendor_partition_set])
-    if shareduid_errors:
-      for error in shareduid_errors:
-        logger.error(error)
-      raise ValueError('sharedUserId APK error. See %s' %
-                       shareduid_violation_modules)
-
-  # host_init_verifier and secilc check only the following partitions:
-  filtered_partitions = {
-      partition: path
-      for partition, path in partition_map.items()
-      if partition in ['system', 'system_ext', 'product', 'vendor', 'odm']
-  }
-
-  # Run host_init_verifier on the combined init rc files.
-  common.RunHostInitVerifier(
-      product_out=output_target_files_temp_dir,
-      partition_map=filtered_partitions)
-
-  # Check that the split sepolicy from the multiple builds can compile.
-  split_sepolicy_cmd = compile_split_sepolicy(output_target_files_temp_dir,
-                                              filtered_partitions)
-  logger.info('Compiling split sepolicy: %s', ' '.join(split_sepolicy_cmd))
-  common.RunAndCheckOutput(split_sepolicy_cmd)
   # Include the compiled policy in an image if requested.
   if OPTIONS.rebuild_sepolicy:
     rebuild_image_with_sepolicy(output_target_files_temp_dir)
 
-  # Run validation checks on the pre-installed APEX files.
-  validate_merged_apex_info(output_target_files_temp_dir, partition_map.keys())
-
   generate_missing_images(output_target_files_temp_dir)
 
   generate_super_empty_image(output_target_files_temp_dir,
@@ -1345,8 +486,8 @@
   # output items to the output target files directory.
 
   if OPTIONS.output_dir:
-    copy_items(output_target_files_temp_dir, OPTIONS.output_dir,
-               OPTIONS.output_item_list)
+    merge_utils.CopyItems(output_target_files_temp_dir, OPTIONS.output_dir,
+                          OPTIONS.output_item_list)
 
   if not OPTIONS.output_target_files:
     return
@@ -1366,33 +507,6 @@
         [OPTIONS.output_target_files, OPTIONS.output_ota])
 
 
-def call_func_with_temp_dir(func, keep_tmp):
-  """Manages the creation and cleanup of the temporary directory.
-
-  This function calls the given function after first creating a temporary
-  directory. It also cleans up the temporary directory.
-
-  Args:
-    func: The function to call. Should accept one parameter, the path to the
-      temporary directory.
-    keep_tmp: Keep the temporary directory after processing is complete.
-  """
-
-  # Create a temporary directory. This will serve as the parent of directories
-  # we use when we extract items from the input target files packages, and also
-  # a scratch directory that we use for temporary files.
-
-  temp_dir = common.MakeTempDir(prefix='merge_target_files_')
-
-  try:
-    func(temp_dir)
-  finally:
-    if keep_tmp:
-      logger.info('keeping %s', temp_dir)
-    else:
-      common.Cleanup()
-
-
 def main():
   """The main function.
 
@@ -1444,7 +558,7 @@
       OPTIONS.output_img = a
     elif o == '--output-super-empty':
       OPTIONS.output_super_empty = a
-    elif o == '--rebuild_recovery':
+    elif o == '--rebuild_recovery' or o == '--rebuild-recovery':
       OPTIONS.rebuild_recovery = True
     elif o == '--allow-duplicate-apkapex-keys':
       OPTIONS.allow_duplicate_apkapex_keys = True
@@ -1488,6 +602,7 @@
           'framework-dexpreopt-tools=',
           'vendor-dexpreopt-config=',
           'rebuild_recovery',
+          'rebuild-recovery',
           'allow-duplicate-apkapex-keys',
           'vendor-otatools=',
           'rebuild-sepolicy',
@@ -1509,7 +624,7 @@
         OPTIONS.framework_item_list)
   else:
     OPTIONS.framework_item_list = DEFAULT_FRAMEWORK_ITEM_LIST
-  OPTIONS.framework_partition_set = item_list_to_partition_set(
+  OPTIONS.framework_partition_set = merge_utils.ItemListToPartitionSet(
       OPTIONS.framework_item_list)
 
   if OPTIONS.framework_misc_info_keys:
@@ -1522,7 +637,7 @@
     OPTIONS.vendor_item_list = common.LoadListFromFile(OPTIONS.vendor_item_list)
   else:
     OPTIONS.vendor_item_list = DEFAULT_VENDOR_ITEM_LIST
-  OPTIONS.vendor_partition_set = item_list_to_partition_set(
+  OPTIONS.vendor_partition_set = merge_utils.ItemListToPartitionSet(
       OPTIONS.vendor_item_list)
 
   if OPTIONS.output_item_list:
@@ -1530,11 +645,17 @@
   else:
     OPTIONS.output_item_list = None
 
-  if not validate_config_lists():
+  if not merge_utils.ValidateConfigLists():
     sys.exit(1)
 
-  call_func_with_temp_dir(lambda temp_dir: merge_target_files(temp_dir),
-                          OPTIONS.keep_tmp)
+  temp_dir = common.MakeTempDir(prefix='merge_target_files_')
+  try:
+    merge_target_files(temp_dir)
+  finally:
+    if OPTIONS.keep_tmp:
+      logger.info('Keeping temp_dir %s', temp_dir)
+    else:
+      common.Cleanup()
 
 
 if __name__ == '__main__':
diff --git a/tools/releasetools/merge/merge_utils.py b/tools/releasetools/merge/merge_utils.py
new file mode 100644
index 0000000..e822061
--- /dev/null
+++ b/tools/releasetools/merge/merge_utils.py
@@ -0,0 +1,187 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2022 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.
+#
+"""Common utility functions shared by merge_* scripts.
+
+Expects items in OPTIONS prepared by merge_target_files.py.
+"""
+
+import fnmatch
+import logging
+import os
+import re
+import shutil
+import zipfile
+
+import common
+
+logger = logging.getLogger(__name__)
+OPTIONS = common.OPTIONS
+
+
+def ExtractItems(input_zip, output_dir, extract_item_list):
+  """Extracts items in extract_item_list from a zip to a dir."""
+
+  # Filter the extract_item_list to remove any items that do not exist in the
+  # zip file. Otherwise, the extraction step will fail.
+
+  with zipfile.ZipFile(input_zip, allowZip64=True) as input_zipfile:
+    input_namelist = input_zipfile.namelist()
+
+  filtered_extract_item_list = []
+  for pattern in extract_item_list:
+    if fnmatch.filter(input_namelist, pattern):
+      filtered_extract_item_list.append(pattern)
+
+  common.UnzipToDir(input_zip, output_dir, filtered_extract_item_list)
+
+
+def CopyItems(from_dir, to_dir, patterns):
+  """Similar to ExtractItems() except uses an input dir instead of zip."""
+  file_paths = []
+  for dirpath, _, filenames in os.walk(from_dir):
+    file_paths.extend(
+        os.path.relpath(path=os.path.join(dirpath, filename), start=from_dir)
+        for filename in filenames)
+
+  filtered_file_paths = set()
+  for pattern in patterns:
+    filtered_file_paths.update(fnmatch.filter(file_paths, pattern))
+
+  for file_path in filtered_file_paths:
+    original_file_path = os.path.join(from_dir, file_path)
+    copied_file_path = os.path.join(to_dir, file_path)
+    copied_file_dir = os.path.dirname(copied_file_path)
+    if not os.path.exists(copied_file_dir):
+      os.makedirs(copied_file_dir)
+    if os.path.islink(original_file_path):
+      os.symlink(os.readlink(original_file_path), copied_file_path)
+    else:
+      shutil.copyfile(original_file_path, copied_file_path)
+
+
+def WriteSortedData(data, path):
+  """Writes the sorted contents of either a list or dict to file.
+
+  This function sorts the contents of the list or dict and then writes the
+  resulting sorted contents to a file specified by path.
+
+  Args:
+    data: The list or dict to sort and write.
+    path: Path to the file to write the sorted values to. The file at path will
+      be overridden if it exists.
+  """
+  with open(path, 'w') as output:
+    for entry in sorted(data):
+      out_str = '{}={}\n'.format(entry, data[entry]) if isinstance(
+          data, dict) else '{}\n'.format(entry)
+      output.write(out_str)
+
+
+# The merge config lists should not attempt to extract items from both
+# builds for any of the following partitions. The partitions in
+# SINGLE_BUILD_PARTITIONS should come entirely from a single build (either
+# framework or vendor, but not both).
+
+_SINGLE_BUILD_PARTITIONS = (
+    'BOOT/',
+    'DATA/',
+    'ODM/',
+    'PRODUCT/',
+    'SYSTEM_EXT/',
+    'RADIO/',
+    'RECOVERY/',
+    'ROOT/',
+    'SYSTEM/',
+    'SYSTEM_OTHER/',
+    'VENDOR/',
+    'VENDOR_DLKM/',
+    'ODM_DLKM/',
+    'SYSTEM_DLKM/',
+)
+
+
+def ValidateConfigLists():
+  """Performs validations on the merge config lists.
+
+  Returns:
+    False if a validation fails, otherwise true.
+  """
+  has_error = False
+
+  # Check that partitions only come from one input.
+  for partition in _SINGLE_BUILD_PARTITIONS:
+    image_path = 'IMAGES/{}.img'.format(partition.lower().replace('/', ''))
+    in_framework = (
+        any(item.startswith(partition) for item in OPTIONS.framework_item_list)
+        or image_path in OPTIONS.framework_item_list)
+    in_vendor = (
+        any(item.startswith(partition) for item in OPTIONS.vendor_item_list) or
+        image_path in OPTIONS.vendor_item_list)
+    if in_framework and in_vendor:
+      logger.error(
+          'Cannot extract items from %s for both the framework and vendor'
+          ' builds. Please ensure only one merge config item list'
+          ' includes %s.', partition, partition)
+      has_error = True
+
+  if any([
+      key in OPTIONS.framework_misc_info_keys
+      for key in ('dynamic_partition_list', 'super_partition_groups')
+  ]):
+    logger.error('Dynamic partition misc info keys should come from '
+                 'the vendor instance of META/misc_info.txt.')
+    has_error = True
+
+  return not has_error
+
+
+# In an item list (framework or vendor), we may see entries that select whole
+# partitions. Such an entry might look like this 'SYSTEM/*' (e.g., for the
+# system partition). The following regex matches this and extracts the
+# partition name.
+
+_PARTITION_ITEM_PATTERN = re.compile(r'^([A-Z_]+)/\*$')
+
+
+def ItemListToPartitionSet(item_list):
+  """Converts a target files item list to a partition set.
+
+  The item list contains items that might look like 'SYSTEM/*' or 'VENDOR/*' or
+  'OTA/android-info.txt'. Items that end in '/*' are assumed to match entire
+  directories where 'SYSTEM' or 'VENDOR' is a directory name that identifies the
+  contents of a partition of the same name. Other items in the list, such as the
+  'OTA' example contain metadata. This function iterates such a list, returning
+  a set that contains the partition entries.
+
+  Args:
+    item_list: A list of items in a target files package.
+
+  Returns:
+    A set of partitions extracted from the list of items.
+  """
+
+  partition_set = set()
+
+  for item in item_list:
+    partition_match = _PARTITION_ITEM_PATTERN.search(item.strip())
+    partition_tag = partition_match.group(
+        1).lower() if partition_match else None
+
+    if partition_tag:
+      partition_set.add(partition_tag)
+
+  return partition_set
diff --git a/tools/releasetools/merge/test_merge_compatibility_checks.py b/tools/releasetools/merge/test_merge_compatibility_checks.py
new file mode 100644
index 0000000..0f319de
--- /dev/null
+++ b/tools/releasetools/merge/test_merge_compatibility_checks.py
@@ -0,0 +1,114 @@
+#
+# Copyright (C) 2022 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.
+#
+
+import os.path
+import shutil
+
+import common
+import merge_compatibility_checks
+import merge_target_files
+import test_utils
+
+
+class MergeCompatibilityChecksTest(test_utils.ReleaseToolsTestCase):
+
+  def setUp(self):
+    self.testdata_dir = test_utils.get_testdata_dir()
+    self.partition_map = {
+        'system': 'system',
+        'system_ext': 'system_ext',
+        'product': 'product',
+        'vendor': 'vendor',
+        'odm': 'odm',
+    }
+    self.OPTIONS = merge_target_files.OPTIONS
+    self.OPTIONS.framework_partition_set = set(
+        ['product', 'system', 'system_ext'])
+    self.OPTIONS.vendor_partition_set = set(['odm', 'vendor'])
+
+  def test_CheckCombinedSepolicy(self):
+    product_out_dir = common.MakeTempDir()
+
+    def write_temp_file(path, data=''):
+      full_path = os.path.join(product_out_dir, path)
+      if not os.path.exists(os.path.dirname(full_path)):
+        os.makedirs(os.path.dirname(full_path))
+      with open(full_path, 'w') as f:
+        f.write(data)
+
+    write_temp_file(
+        'system/etc/vintf/compatibility_matrix.device.xml', """
+      <compatibility-matrix>
+        <sepolicy>
+          <kernel-sepolicy-version>30</kernel-sepolicy-version>
+        </sepolicy>
+      </compatibility-matrix>""")
+    write_temp_file('vendor/etc/selinux/plat_sepolicy_vers.txt', '30.0')
+
+    write_temp_file('system/etc/selinux/plat_sepolicy.cil')
+    write_temp_file('system/etc/selinux/mapping/30.0.cil')
+    write_temp_file('product/etc/selinux/mapping/30.0.cil')
+    write_temp_file('vendor/etc/selinux/vendor_sepolicy.cil')
+    write_temp_file('vendor/etc/selinux/plat_pub_versioned.cil')
+
+    cmd = merge_compatibility_checks.CheckCombinedSepolicy(
+        product_out_dir, self.partition_map, execute=False)
+    self.assertEqual(' '.join(cmd),
+                     ('secilc -m -M true -G -N -c 30 '
+                      '-o {OTP}/META/combined_sepolicy -f /dev/null '
+                      '{OTP}/system/etc/selinux/plat_sepolicy.cil '
+                      '{OTP}/system/etc/selinux/mapping/30.0.cil '
+                      '{OTP}/vendor/etc/selinux/vendor_sepolicy.cil '
+                      '{OTP}/vendor/etc/selinux/plat_pub_versioned.cil '
+                      '{OTP}/product/etc/selinux/mapping/30.0.cil').format(
+                          OTP=product_out_dir))
+
+  def _copy_apex(self, source, output_dir, partition):
+    shutil.copy(
+        source,
+        os.path.join(output_dir, partition, 'apex', os.path.basename(source)))
+
+  @test_utils.SkipIfExternalToolsUnavailable()
+  def test_CheckApexDuplicatePackages(self):
+    output_dir = common.MakeTempDir()
+    os.makedirs(os.path.join(output_dir, 'SYSTEM/apex'))
+    os.makedirs(os.path.join(output_dir, 'VENDOR/apex'))
+
+    self._copy_apex(
+        os.path.join(self.testdata_dir, 'has_apk.apex'), output_dir, 'SYSTEM')
+    self._copy_apex(
+        os.path.join(test_utils.get_current_dir(),
+                     'com.android.apex.compressed.v1.capex'), output_dir,
+        'VENDOR')
+    self.assertEqual(
+        len(
+            merge_compatibility_checks.CheckApexDuplicatePackages(
+                output_dir, self.partition_map)), 0)
+
+  @test_utils.SkipIfExternalToolsUnavailable()
+  def test_CheckApexDuplicatePackages_RaisesOnPackageInMultiplePartitions(self):
+    output_dir = common.MakeTempDir()
+    os.makedirs(os.path.join(output_dir, 'SYSTEM/apex'))
+    os.makedirs(os.path.join(output_dir, 'VENDOR/apex'))
+
+    same_apex_package = os.path.join(self.testdata_dir, 'has_apk.apex')
+    self._copy_apex(same_apex_package, output_dir, 'SYSTEM')
+    self._copy_apex(same_apex_package, output_dir, 'VENDOR')
+    self.assertEqual(
+        merge_compatibility_checks.CheckApexDuplicatePackages(
+            output_dir, self.partition_map)[0],
+        'Duplicate APEX package_names found in multiple partitions: com.android.wifi'
+    )
diff --git a/tools/releasetools/merge/test_merge_meta.py b/tools/releasetools/merge/test_merge_meta.py
new file mode 100644
index 0000000..34fe580
--- /dev/null
+++ b/tools/releasetools/merge/test_merge_meta.py
@@ -0,0 +1,110 @@
+#
+# Copyright (C) 2017 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.
+#
+
+import os.path
+import shutil
+
+import common
+import merge_meta
+import merge_target_files
+import test_utils
+
+
+class MergeMetaTest(test_utils.ReleaseToolsTestCase):
+
+  def setUp(self):
+    self.testdata_dir = test_utils.get_testdata_dir()
+    self.OPTIONS = merge_target_files.OPTIONS
+    self.OPTIONS.framework_partition_set = set(
+        ['product', 'system', 'system_ext'])
+    self.OPTIONS.vendor_partition_set = set(['odm', 'vendor'])
+
+  def test_MergePackageKeys_ReturnsTrueIfNoConflicts(self):
+    output_meta_dir = common.MakeTempDir()
+
+    framework_meta_dir = common.MakeTempDir()
+    os.symlink(
+        os.path.join(self.testdata_dir, 'apexkeys_framework.txt'),
+        os.path.join(framework_meta_dir, 'apexkeys.txt'))
+
+    vendor_meta_dir = common.MakeTempDir()
+    os.symlink(
+        os.path.join(self.testdata_dir, 'apexkeys_vendor.txt'),
+        os.path.join(vendor_meta_dir, 'apexkeys.txt'))
+
+    merge_meta.MergePackageKeys(framework_meta_dir, vendor_meta_dir,
+                                output_meta_dir, 'apexkeys.txt')
+
+    merged_entries = []
+    merged_path = os.path.join(self.testdata_dir, 'apexkeys_merge.txt')
+
+    with open(merged_path) as f:
+      merged_entries = f.read().split('\n')
+
+    output_entries = []
+    output_path = os.path.join(output_meta_dir, 'apexkeys.txt')
+
+    with open(output_path) as f:
+      output_entries = f.read().split('\n')
+
+    return self.assertEqual(merged_entries, output_entries)
+
+  def test_MergePackageKeys_ReturnsFalseIfConflictsPresent(self):
+    output_meta_dir = common.MakeTempDir()
+
+    framework_meta_dir = common.MakeTempDir()
+    os.symlink(
+        os.path.join(self.testdata_dir, 'apexkeys_framework.txt'),
+        os.path.join(framework_meta_dir, 'apexkeys.txt'))
+
+    conflict_meta_dir = common.MakeTempDir()
+    os.symlink(
+        os.path.join(self.testdata_dir, 'apexkeys_framework_conflict.txt'),
+        os.path.join(conflict_meta_dir, 'apexkeys.txt'))
+
+    self.assertRaises(ValueError, merge_meta.MergePackageKeys,
+                      framework_meta_dir, conflict_meta_dir, output_meta_dir,
+                      'apexkeys.txt')
+
+  def test_MergePackageKeys_HandlesApkCertsSyntax(self):
+    output_meta_dir = common.MakeTempDir()
+
+    framework_meta_dir = common.MakeTempDir()
+    os.symlink(
+        os.path.join(self.testdata_dir, 'apkcerts_framework.txt'),
+        os.path.join(framework_meta_dir, 'apkcerts.txt'))
+
+    vendor_meta_dir = common.MakeTempDir()
+    os.symlink(
+        os.path.join(self.testdata_dir, 'apkcerts_vendor.txt'),
+        os.path.join(vendor_meta_dir, 'apkcerts.txt'))
+
+    merge_meta.MergePackageKeys(framework_meta_dir, vendor_meta_dir,
+                                output_meta_dir, 'apkcerts.txt')
+
+    merged_entries = []
+    merged_path = os.path.join(self.testdata_dir, 'apkcerts_merge.txt')
+
+    with open(merged_path) as f:
+      merged_entries = f.read().split('\n')
+
+    output_entries = []
+    output_path = os.path.join(output_meta_dir, 'apkcerts.txt')
+
+    with open(output_path) as f:
+      output_entries = f.read().split('\n')
+
+    return self.assertEqual(merged_entries, output_entries)
diff --git a/tools/releasetools/merge/test_merge_target_files.py b/tools/releasetools/merge/test_merge_target_files.py
deleted file mode 100644
index 088ebee..0000000
--- a/tools/releasetools/merge/test_merge_target_files.py
+++ /dev/null
@@ -1,288 +0,0 @@
-#
-# Copyright (C) 2017 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.
-#
-
-import os.path
-import shutil
-
-import common
-import merge_target_files
-import test_utils
-from merge_target_files import (
-    validate_config_lists, DEFAULT_FRAMEWORK_ITEM_LIST,
-    DEFAULT_VENDOR_ITEM_LIST, DEFAULT_FRAMEWORK_MISC_INFO_KEYS, copy_items,
-    item_list_to_partition_set, merge_package_keys_txt, compile_split_sepolicy,
-    validate_merged_apex_info)
-
-
-class MergeTargetFilesTest(test_utils.ReleaseToolsTestCase):
-
-  def setUp(self):
-    self.testdata_dir = test_utils.get_testdata_dir()
-    self.OPTIONS = merge_target_files.OPTIONS
-    self.OPTIONS.framework_item_list = DEFAULT_FRAMEWORK_ITEM_LIST
-    self.OPTIONS.framework_misc_info_keys = DEFAULT_FRAMEWORK_MISC_INFO_KEYS
-    self.OPTIONS.vendor_item_list = DEFAULT_VENDOR_ITEM_LIST
-    self.OPTIONS.framework_partition_set = set(
-        ['product', 'system', 'system_ext'])
-    self.OPTIONS.vendor_partition_set = set(['odm', 'vendor'])
-
-  def test_copy_items_CopiesItemsMatchingPatterns(self):
-
-    def createEmptyFile(path):
-      if not os.path.exists(os.path.dirname(path)):
-        os.makedirs(os.path.dirname(path))
-      open(path, 'a').close()
-      return path
-
-    def createSymLink(source, dest):
-      os.symlink(source, dest)
-      return dest
-
-    def getRelPaths(start, filepaths):
-      return set(
-          os.path.relpath(path=filepath, start=start) for filepath in filepaths)
-
-    input_dir = common.MakeTempDir()
-    output_dir = common.MakeTempDir()
-    expected_copied_items = []
-    actual_copied_items = []
-    patterns = ['*.cpp', 'subdir/*.txt']
-
-    # Create various files that we expect to get copied because they
-    # match one of the patterns.
-    expected_copied_items.extend([
-        createEmptyFile(os.path.join(input_dir, 'a.cpp')),
-        createEmptyFile(os.path.join(input_dir, 'b.cpp')),
-        createEmptyFile(os.path.join(input_dir, 'subdir', 'c.txt')),
-        createEmptyFile(os.path.join(input_dir, 'subdir', 'd.txt')),
-        createEmptyFile(
-            os.path.join(input_dir, 'subdir', 'subsubdir', 'e.txt')),
-        createSymLink('a.cpp', os.path.join(input_dir, 'a_link.cpp')),
-    ])
-    # Create some more files that we expect to not get copied.
-    createEmptyFile(os.path.join(input_dir, 'a.h'))
-    createEmptyFile(os.path.join(input_dir, 'b.h'))
-    createEmptyFile(os.path.join(input_dir, 'subdir', 'subsubdir', 'f.gif'))
-    createSymLink('a.h', os.path.join(input_dir, 'a_link.h'))
-
-    # Copy items.
-    copy_items(input_dir, output_dir, patterns)
-
-    # Assert the actual copied items match the ones we expected.
-    for dirpath, _, filenames in os.walk(output_dir):
-      actual_copied_items.extend(
-          os.path.join(dirpath, filename) for filename in filenames)
-    self.assertEqual(
-        getRelPaths(output_dir, actual_copied_items),
-        getRelPaths(input_dir, expected_copied_items))
-    self.assertEqual(
-        os.readlink(os.path.join(output_dir, 'a_link.cpp')), 'a.cpp')
-
-  def test_validate_config_lists_ReturnsFalseIfMissingDefaultItem(self):
-    self.OPTIONS.framework_item_list = list(DEFAULT_FRAMEWORK_ITEM_LIST)
-    self.OPTIONS.framework_item_list.remove('SYSTEM/*')
-    self.assertFalse(validate_config_lists())
-
-  def test_validate_config_lists_ReturnsTrueIfDefaultItemInDifferentList(self):
-    self.OPTIONS.framework_item_list = list(DEFAULT_FRAMEWORK_ITEM_LIST)
-    self.OPTIONS.framework_item_list.remove('ROOT/*')
-    self.OPTIONS.vendor_item_list = list(DEFAULT_VENDOR_ITEM_LIST)
-    self.OPTIONS.vendor_item_list.append('ROOT/*')
-    self.assertTrue(validate_config_lists())
-
-  def test_validate_config_lists_ReturnsTrueIfExtraItem(self):
-    self.OPTIONS.framework_item_list = list(DEFAULT_FRAMEWORK_ITEM_LIST)
-    self.OPTIONS.framework_item_list.append('MY_NEW_PARTITION/*')
-    self.assertTrue(validate_config_lists())
-
-  def test_validate_config_lists_ReturnsFalseIfSharedExtractedPartition(self):
-    self.OPTIONS.vendor_item_list = list(DEFAULT_VENDOR_ITEM_LIST)
-    self.OPTIONS.vendor_item_list.append('SYSTEM/my_system_file')
-    self.assertFalse(validate_config_lists())
-
-  def test_validate_config_lists_ReturnsFalseIfSharedExtractedPartitionImage(
-      self):
-    self.OPTIONS.vendor_item_list = list(DEFAULT_VENDOR_ITEM_LIST)
-    self.OPTIONS.vendor_item_list.append('IMAGES/system.img')
-    self.assertFalse(validate_config_lists())
-
-  def test_validate_config_lists_ReturnsFalseIfBadSystemMiscInfoKeys(self):
-    for bad_key in ['dynamic_partition_list', 'super_partition_groups']:
-      self.OPTIONS.framework_misc_info_keys = list(
-          DEFAULT_FRAMEWORK_MISC_INFO_KEYS)
-      self.OPTIONS.framework_misc_info_keys.append(bad_key)
-      self.assertFalse(validate_config_lists())
-
-  def test_merge_package_keys_txt_ReturnsTrueIfNoConflicts(self):
-    output_meta_dir = common.MakeTempDir()
-
-    framework_meta_dir = common.MakeTempDir()
-    os.symlink(
-        os.path.join(self.testdata_dir, 'apexkeys_framework.txt'),
-        os.path.join(framework_meta_dir, 'apexkeys.txt'))
-
-    vendor_meta_dir = common.MakeTempDir()
-    os.symlink(
-        os.path.join(self.testdata_dir, 'apexkeys_vendor.txt'),
-        os.path.join(vendor_meta_dir, 'apexkeys.txt'))
-
-    merge_package_keys_txt(framework_meta_dir, vendor_meta_dir, output_meta_dir,
-                           'apexkeys.txt')
-
-    merged_entries = []
-    merged_path = os.path.join(self.testdata_dir, 'apexkeys_merge.txt')
-
-    with open(merged_path) as f:
-      merged_entries = f.read().split('\n')
-
-    output_entries = []
-    output_path = os.path.join(output_meta_dir, 'apexkeys.txt')
-
-    with open(output_path) as f:
-      output_entries = f.read().split('\n')
-
-    return self.assertEqual(merged_entries, output_entries)
-
-  def test_process_apex_keys_apk_certs_ReturnsFalseIfConflictsPresent(self):
-    output_meta_dir = common.MakeTempDir()
-
-    framework_meta_dir = common.MakeTempDir()
-    os.symlink(
-        os.path.join(self.testdata_dir, 'apexkeys_framework.txt'),
-        os.path.join(framework_meta_dir, 'apexkeys.txt'))
-
-    conflict_meta_dir = common.MakeTempDir()
-    os.symlink(
-        os.path.join(self.testdata_dir, 'apexkeys_framework_conflict.txt'),
-        os.path.join(conflict_meta_dir, 'apexkeys.txt'))
-
-    self.assertRaises(ValueError, merge_package_keys_txt, framework_meta_dir,
-                      conflict_meta_dir, output_meta_dir, 'apexkeys.txt')
-
-  def test_process_apex_keys_apk_certs_HandlesApkCertsSyntax(self):
-    output_meta_dir = common.MakeTempDir()
-
-    framework_meta_dir = common.MakeTempDir()
-    os.symlink(
-        os.path.join(self.testdata_dir, 'apkcerts_framework.txt'),
-        os.path.join(framework_meta_dir, 'apkcerts.txt'))
-
-    vendor_meta_dir = common.MakeTempDir()
-    os.symlink(
-        os.path.join(self.testdata_dir, 'apkcerts_vendor.txt'),
-        os.path.join(vendor_meta_dir, 'apkcerts.txt'))
-
-    merge_package_keys_txt(framework_meta_dir, vendor_meta_dir, output_meta_dir,
-                           'apkcerts.txt')
-
-    merged_entries = []
-    merged_path = os.path.join(self.testdata_dir, 'apkcerts_merge.txt')
-
-    with open(merged_path) as f:
-      merged_entries = f.read().split('\n')
-
-    output_entries = []
-    output_path = os.path.join(output_meta_dir, 'apkcerts.txt')
-
-    with open(output_path) as f:
-      output_entries = f.read().split('\n')
-
-    return self.assertEqual(merged_entries, output_entries)
-
-  def test_item_list_to_partition_set(self):
-    item_list = [
-        'META/apexkeys.txt',
-        'META/apkcerts.txt',
-        'META/filesystem_config.txt',
-        'PRODUCT/*',
-        'SYSTEM/*',
-        'SYSTEM_EXT/*',
-    ]
-    partition_set = item_list_to_partition_set(item_list)
-    self.assertEqual(set(['product', 'system', 'system_ext']), partition_set)
-
-  def test_compile_split_sepolicy(self):
-    product_out_dir = common.MakeTempDir()
-
-    def write_temp_file(path, data=''):
-      full_path = os.path.join(product_out_dir, path)
-      if not os.path.exists(os.path.dirname(full_path)):
-        os.makedirs(os.path.dirname(full_path))
-      with open(full_path, 'w') as f:
-        f.write(data)
-
-    write_temp_file(
-        'system/etc/vintf/compatibility_matrix.device.xml', """
-      <compatibility-matrix>
-        <sepolicy>
-          <kernel-sepolicy-version>30</kernel-sepolicy-version>
-        </sepolicy>
-      </compatibility-matrix>""")
-    write_temp_file('vendor/etc/selinux/plat_sepolicy_vers.txt', '30.0')
-
-    write_temp_file('system/etc/selinux/plat_sepolicy.cil')
-    write_temp_file('system/etc/selinux/mapping/30.0.cil')
-    write_temp_file('product/etc/selinux/mapping/30.0.cil')
-    write_temp_file('vendor/etc/selinux/vendor_sepolicy.cil')
-    write_temp_file('vendor/etc/selinux/plat_pub_versioned.cil')
-
-    cmd = compile_split_sepolicy(product_out_dir, {
-        'system': 'system',
-        'product': 'product',
-        'vendor': 'vendor',
-    })
-    self.assertEqual(' '.join(cmd),
-                     ('secilc -m -M true -G -N -c 30 '
-                      '-o {OTP}/META/combined_sepolicy -f /dev/null '
-                      '{OTP}/system/etc/selinux/plat_sepolicy.cil '
-                      '{OTP}/system/etc/selinux/mapping/30.0.cil '
-                      '{OTP}/vendor/etc/selinux/vendor_sepolicy.cil '
-                      '{OTP}/vendor/etc/selinux/plat_pub_versioned.cil '
-                      '{OTP}/product/etc/selinux/mapping/30.0.cil').format(
-                          OTP=product_out_dir))
-
-  def _copy_apex(self, source, output_dir, partition):
-    shutil.copy(
-        source,
-        os.path.join(output_dir, partition, 'apex', os.path.basename(source)))
-
-  @test_utils.SkipIfExternalToolsUnavailable()
-  def test_validate_merged_apex_info(self):
-    output_dir = common.MakeTempDir()
-    os.makedirs(os.path.join(output_dir, 'SYSTEM/apex'))
-    os.makedirs(os.path.join(output_dir, 'VENDOR/apex'))
-
-    self._copy_apex(
-        os.path.join(self.testdata_dir, 'has_apk.apex'), output_dir, 'SYSTEM')
-    self._copy_apex(
-        os.path.join(test_utils.get_current_dir(),
-                     'com.android.apex.compressed.v1.capex'), output_dir,
-        'VENDOR')
-    validate_merged_apex_info(output_dir, ('system', 'vendor'))
-
-  @test_utils.SkipIfExternalToolsUnavailable()
-  def test_validate_merged_apex_info_RaisesOnPackageInMultiplePartitions(self):
-    output_dir = common.MakeTempDir()
-    os.makedirs(os.path.join(output_dir, 'SYSTEM/apex'))
-    os.makedirs(os.path.join(output_dir, 'VENDOR/apex'))
-
-    same_apex_package = os.path.join(self.testdata_dir, 'has_apk.apex')
-    self._copy_apex(same_apex_package, output_dir, 'SYSTEM')
-    self._copy_apex(same_apex_package, output_dir, 'VENDOR')
-    self.assertRaisesRegexp(
-        common.ExternalError,
-        'Duplicate APEX packages found in multiple partitions: com.android.wifi',
-        validate_merged_apex_info, output_dir, ('system', 'vendor'))
diff --git a/tools/releasetools/merge/test_merge_utils.py b/tools/releasetools/merge/test_merge_utils.py
new file mode 100644
index 0000000..d0cd2cf
--- /dev/null
+++ b/tools/releasetools/merge/test_merge_utils.py
@@ -0,0 +1,118 @@
+#
+# Copyright (C) 2017 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.
+#
+
+import os.path
+
+import common
+import merge_target_files
+import merge_utils
+import test_utils
+from merge_target_files import (
+    DEFAULT_FRAMEWORK_ITEM_LIST,
+    DEFAULT_VENDOR_ITEM_LIST,
+    DEFAULT_FRAMEWORK_MISC_INFO_KEYS,
+)
+
+
+class MergeUtilsTest(test_utils.ReleaseToolsTestCase):
+
+  def setUp(self):
+    self.OPTIONS = merge_target_files.OPTIONS
+    self.OPTIONS.framework_item_list = DEFAULT_FRAMEWORK_ITEM_LIST
+    self.OPTIONS.framework_misc_info_keys = DEFAULT_FRAMEWORK_MISC_INFO_KEYS
+    self.OPTIONS.vendor_item_list = DEFAULT_VENDOR_ITEM_LIST
+
+  def test_CopyItems_CopiesItemsMatchingPatterns(self):
+
+    def createEmptyFile(path):
+      if not os.path.exists(os.path.dirname(path)):
+        os.makedirs(os.path.dirname(path))
+      open(path, 'a').close()
+      return path
+
+    def createSymLink(source, dest):
+      os.symlink(source, dest)
+      return dest
+
+    def getRelPaths(start, filepaths):
+      return set(
+          os.path.relpath(path=filepath, start=start) for filepath in filepaths)
+
+    input_dir = common.MakeTempDir()
+    output_dir = common.MakeTempDir()
+    expected_copied_items = []
+    actual_copied_items = []
+    patterns = ['*.cpp', 'subdir/*.txt']
+
+    # Create various files that we expect to get copied because they
+    # match one of the patterns.
+    expected_copied_items.extend([
+        createEmptyFile(os.path.join(input_dir, 'a.cpp')),
+        createEmptyFile(os.path.join(input_dir, 'b.cpp')),
+        createEmptyFile(os.path.join(input_dir, 'subdir', 'c.txt')),
+        createEmptyFile(os.path.join(input_dir, 'subdir', 'd.txt')),
+        createEmptyFile(
+            os.path.join(input_dir, 'subdir', 'subsubdir', 'e.txt')),
+        createSymLink('a.cpp', os.path.join(input_dir, 'a_link.cpp')),
+    ])
+    # Create some more files that we expect to not get copied.
+    createEmptyFile(os.path.join(input_dir, 'a.h'))
+    createEmptyFile(os.path.join(input_dir, 'b.h'))
+    createEmptyFile(os.path.join(input_dir, 'subdir', 'subsubdir', 'f.gif'))
+    createSymLink('a.h', os.path.join(input_dir, 'a_link.h'))
+
+    # Copy items.
+    merge_utils.CopyItems(input_dir, output_dir, patterns)
+
+    # Assert the actual copied items match the ones we expected.
+    for dirpath, _, filenames in os.walk(output_dir):
+      actual_copied_items.extend(
+          os.path.join(dirpath, filename) for filename in filenames)
+    self.assertEqual(
+        getRelPaths(output_dir, actual_copied_items),
+        getRelPaths(input_dir, expected_copied_items))
+    self.assertEqual(
+        os.readlink(os.path.join(output_dir, 'a_link.cpp')), 'a.cpp')
+
+  def test_ValidateConfigLists_ReturnsFalseIfSharedExtractedPartition(self):
+    self.OPTIONS.vendor_item_list = list(DEFAULT_VENDOR_ITEM_LIST)
+    self.OPTIONS.vendor_item_list.append('SYSTEM/my_system_file')
+    self.assertFalse(merge_utils.ValidateConfigLists())
+
+  def test_ValidateConfigLists_ReturnsFalseIfSharedExtractedPartitionImage(
+      self):
+    self.OPTIONS.vendor_item_list = list(DEFAULT_VENDOR_ITEM_LIST)
+    self.OPTIONS.vendor_item_list.append('IMAGES/system.img')
+    self.assertFalse(merge_utils.ValidateConfigLists())
+
+  def test_ValidateConfigLists_ReturnsFalseIfBadSystemMiscInfoKeys(self):
+    for bad_key in ['dynamic_partition_list', 'super_partition_groups']:
+      self.OPTIONS.framework_misc_info_keys = list(
+          DEFAULT_FRAMEWORK_MISC_INFO_KEYS)
+      self.OPTIONS.framework_misc_info_keys.append(bad_key)
+      self.assertFalse(merge_utils.ValidateConfigLists())
+
+  def test_ItemListToPartitionSet(self):
+    item_list = [
+        'META/apexkeys.txt',
+        'META/apkcerts.txt',
+        'META/filesystem_config.txt',
+        'PRODUCT/*',
+        'SYSTEM/*',
+        'SYSTEM_EXT/*',
+    ]
+    partition_set = merge_utils.ItemListToPartitionSet(item_list)
+    self.assertEqual(set(['product', 'system', 'system_ext']), partition_set)