diff --git a/tools/releasetools/Android.bp b/tools/releasetools/Android.bp
index e1543e7..b12a77a 100644
--- a/tools/releasetools/Android.bp
+++ b/tools/releasetools/Android.bp
@@ -368,6 +368,32 @@
     ],
 }
 
+python_defaults {
+    name: "releasetools_find_shareduid_violation_defaults",
+    srcs: [
+        "find_shareduid_violation.py",
+    ],
+    libs: [
+        "releasetools_common",
+    ],
+}
+
+python_binary_host {
+    name: "find_shareduid_violation",
+    defaults: [
+        "releasetools_binary_defaults",
+        "releasetools_find_shareduid_violation_defaults",
+    ],
+}
+
+python_library_host {
+    name: "releasetools_find_shareduid_violation",
+    defaults: [
+        "releasetools_find_shareduid_violation_defaults",
+        "releasetools_library_defaults",
+    ],
+}
+
 python_binary_host {
     name: "make_recovery_patch",
     defaults: ["releasetools_binary_defaults"],
@@ -402,6 +428,7 @@
         "releasetools_build_super_image",
         "releasetools_check_target_files_vintf",
         "releasetools_common",
+        "releasetools_find_shareduid_violation",
         "releasetools_img_from_target_files",
         "releasetools_ota_from_target_files",
     ],
@@ -504,6 +531,7 @@
         "releasetools_build_super_image",
         "releasetools_check_target_files_vintf",
         "releasetools_common",
+        "releasetools_find_shareduid_violation",
         "releasetools_img_from_target_files",
         "releasetools_ota_from_target_files",
         "releasetools_verity_utils",
diff --git a/tools/releasetools/find_shareduid_violation.py b/tools/releasetools/find_shareduid_violation.py
new file mode 100755
index 0000000..35acde3
--- /dev/null
+++ b/tools/releasetools/find_shareduid_violation.py
@@ -0,0 +1,175 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2019 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+"""Find APK sharedUserId violators.
+
+Usage: find_shareduid_violation [args]
+
+  --product_out
+    PRODUCT_OUT directory
+
+  --aapt
+    Path to aapt or aapt2
+
+  --copy_out_system
+    TARGET_COPY_OUT_SYSTEM
+
+  --copy_out_vendor_
+    TARGET_COPY_OUT_VENDOR
+
+  --copy_out_product
+    TARGET_COPY_OUT_PRODUCT
+
+  --copy_out_system_ext
+    TARGET_COPY_OUT_SYSTEM_EXT
+"""
+
+import json
+import logging
+import os
+import re
+import subprocess
+import sys
+
+from collections import defaultdict
+from glob import glob
+
+import common
+
+logger = logging.getLogger(__name__)
+
+OPTIONS = common.OPTIONS
+OPTIONS.product_out = os.environ.get("PRODUCT_OUT")
+OPTIONS.aapt = "aapt2"
+OPTIONS.copy_out_system = "system"
+OPTIONS.copy_out_vendor = "vendor"
+OPTIONS.copy_out_product = "product"
+OPTIONS.copy_out_system_ext = "system_ext"
+
+
+def execute(cmd):
+  p = subprocess.Popen(
+      cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+  out, err = map(lambda b: b.decode("utf-8"), p.communicate())
+  return p.returncode == 0, out, err
+
+
+def make_aapt_cmds(aapt, apk):
+  return [
+      aapt + " dump " + apk + " --file AndroidManifest.xml",
+      aapt + " dump xmltree " + apk + " --file AndroidManifest.xml"
+  ]
+
+
+def extract_shared_uid(aapt, apk):
+  for cmd in make_aapt_cmds(aapt, apk):
+    success, manifest, error_msg = execute(cmd)
+    if success:
+      break
+  else:
+    logger.error(error_msg)
+    sys.exit()
+
+  pattern = re.compile(r"sharedUserId.*=\"([^\"]*)")
+
+  for line in manifest.split("\n"):
+    match = pattern.search(line)
+    if match:
+      return match.group(1)
+  return None
+
+
+def FindShareduidViolation(product_out, partition_map, aapt="aapt2"):
+  """Find sharedUserId violators in the given partitions.
+
+  Args:
+    product_out: The base directory containing the partition directories.
+    partition_map: A map of partition name -> directory name.
+    aapt: The name of the aapt binary. Defaults to aapt2.
+
+  Returns:
+    A string containing a JSON object describing the shared UIDs.
+  """
+  shareduid_app_dict = defaultdict(lambda: defaultdict(list))
+
+  for part, location in partition_map.items():
+    for f in glob(os.path.join(product_out, location, "*", "*", "*.apk")):
+      apk_file = os.path.basename(f)
+      shared_uid = extract_shared_uid(aapt, f)
+
+      if shared_uid is None:
+        continue
+      shareduid_app_dict[shared_uid][part].append(apk_file)
+
+  # Only output sharedUserId values that appear in >1 partition.
+  output = {}
+  for uid, partitions in shareduid_app_dict.items():
+    if len(partitions) > 1:
+      output[uid] = shareduid_app_dict[uid]
+
+  return json.dumps(output, indent=2, sort_keys=True)
+
+
+def main():
+  common.InitLogging()
+
+  def option_handler(o, a):
+    if o == "--product_out":
+      OPTIONS.product_out = a
+    elif o == "--aapt":
+      OPTIONS.aapt = a
+    elif o == "--copy_out_system":
+      OPTIONS.copy_out_system = a
+    elif o == "--copy_out_vendor":
+      OPTIONS.copy_out_vendor = a
+    elif o == "--copy_out_product":
+      OPTIONS.copy_out_product = a
+    elif o == "--copy_out_system_ext":
+      OPTIONS.copy_out_system_ext = a
+    else:
+      return False
+    return True
+
+  args = common.ParseOptions(
+      sys.argv[1:],
+      __doc__,
+      extra_long_opts=[
+          "product_out=",
+          "aapt=",
+          "copy_out_system=",
+          "copy_out_vendor=",
+          "copy_out_product=",
+          "copy_out_system_ext=",
+      ],
+      extra_option_handler=option_handler)
+
+  if args:
+    common.Usage(__doc__)
+    sys.exit(1)
+
+  partition_map = {
+      "system": OPTIONS.copy_out_system,
+      "vendor": OPTIONS.copy_out_vendor,
+      "product": OPTIONS.copy_out_product,
+      "system_ext": OPTIONS.copy_out_system_ext,
+  }
+
+  print(
+      FindShareduidViolation(OPTIONS.product_out, partition_map, OPTIONS.aapt))
+
+
+if __name__ == "__main__":
+  main()
diff --git a/tools/releasetools/merge_target_files.py b/tools/releasetools/merge_target_files.py
index 2da5cc0..0d135d6 100755
--- a/tools/releasetools/merge_target_files.py
+++ b/tools/releasetools/merge_target_files.py
@@ -98,6 +98,7 @@
 import check_target_files_vintf
 import common
 import img_from_target_files
+import find_shareduid_violation
 import ota_from_target_files
 
 logger = logging.getLogger(__name__)
@@ -943,6 +944,21 @@
   if not check_target_files_vintf.CheckVintf(output_target_files_temp_dir):
     raise RuntimeError('Incompatible VINTF metadata')
 
+  shareduid_violation_modules = os.path.join(
+      output_target_files_temp_dir, 'META', 'shareduid_violation_modules.json')
+  with open(shareduid_violation_modules, 'w') as f:
+    partition_map = {
+        'system': 'SYSTEM',
+        'vendor': 'VENDOR',
+        'product': 'PRODUCT',
+        'system_ext': 'SYSTEM_EXT',
+    }
+    violation = find_shareduid_violation.FindShareduidViolation(
+        output_target_files_temp_dir, partition_map)
+    f.write(violation)
+    # TODO(b/171431774): Add a check to common.py to check if the
+    # shared UIDs cross the input build partition boundary.
+
   generate_images(output_target_files_temp_dir, rebuild_recovery)
 
   generate_super_empty_image(output_target_files_temp_dir, output_super_empty)