diff --git a/tools/releasetools/merge_target_files.py b/tools/releasetools/merge_target_files.py
index 0d135d6..ba9e740 100755
--- a/tools/releasetools/merge_target_files.py
+++ b/tools/releasetools/merge_target_files.py
@@ -85,6 +85,7 @@
 from __future__ import print_function
 
 import fnmatch
+import json
 import logging
 import os
 import re
@@ -944,20 +945,32 @@
   if not check_target_files_vintf.CheckVintf(output_target_files_temp_dir):
     raise RuntimeError('Incompatible VINTF metadata')
 
+  # 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:
-    partition_map = {
-        'system': 'SYSTEM',
-        'vendor': 'VENDOR',
-        'product': 'PRODUCT',
-        'system_ext': 'SYSTEM_EXT',
-    }
+    framework_partitions = item_list_to_partition_set(framework_item_list)
+    vendor_partitions = item_list_to_partition_set(vendor_item_list)
+
+    partition_map = {}
+    for partition in (framework_partitions.union(vendor_partitions)):
+      partition_map[partition.lower()] = partition.upper()
     violation = find_shareduid_violation.FindShareduidViolation(
         output_target_files_temp_dir, partition_map)
+
+    # Write the output to a file to enable debugging.
     f.write(violation)
-    # TODO(b/171431774): Add a check to common.py to check if the
-    # shared UIDs cross the input build partition boundary.
+
+    # Check for violations across the input builds' partition groups.
+    shareduid_errors = common.SharedUidPartitionViolations(
+        json.loads(violation), [framework_partitions, vendor_partitions])
+    if shareduid_errors:
+      for error in shareduid_errors:
+        logger.error(error)
+      raise ValueError('sharedUserId APK error. See %s' %
+                       shareduid_violation_modules)
 
   generate_images(output_target_files_temp_dir, rebuild_recovery)