diff --git a/vndk/tools/system_image_diff.py b/vndk/tools/system_image_diff.py
new file mode 100755
index 000000000..cd9ebfb7e
--- /dev/null
+++ b/vndk/tools/system_image_diff.py
@@ -0,0 +1,141 @@
+#!/usr/bin/env python3
+
+import argparse
+import csv
+import glob
+import json
+import os
+import sys
+
+HELP_MSG = '''
+This script computes the differences between two system images (system1 -
+system2), and lists the files grouped by package. The difference is just based
+on the existence of the file, not on its contents.
+'''
+
+VENDOR_PATH_MAP = {
+    'vendor/google' : 'Google',
+    'vendor/unbundled_google': 'Google',
+    'vendor/verizon' : 'Verizon',
+    'vendor/qcom' : 'Qualcomm',
+    'vendor/tmobile' : 'TMobile',
+    'vendor/mediatek' : 'Mediatek',
+    'vendor/htc' : 'HTC',
+    'vendor/realtek' : 'Realtek'
+}
+
+def system_files(path):
+  """Returns an array of the files under /system, recursively, and ignoring
+  symbolic-links"""
+  system_files = []
+  system_prefix = os.path.join(path, 'system')
+  # Skip trailing '/'
+  system_prefix_len = len(system_prefix) + 1
+
+  for root, dirs, files in os.walk(system_prefix, topdown=True):
+    for file in files:
+      # Ignore symbolic links.
+      if not os.path.islink(os.path.join(root, file)):
+        system_files.append(os.path.join(root[system_prefix_len:], file))
+
+  return system_files
+
+def system_files_to_package_map(path):
+  """Returns a dictionary mapping from each file in the /system partition to its
+  package, according to modules-info.json."""
+  system_files_to_package_map = {}
+  system_prefix = os.path.join(path, 'system')
+  # Skip trailing '/'
+  system_prefix_len = len(system_prefix) + 1
+
+  with open(os.path.join(path, 'module-info.json')) as module_info_json:
+    module_info = json.load(module_info_json)
+    for module in module_info:
+      installs = module_info[module]['installed']
+      for install in installs:
+        if install.startswith(system_prefix):
+          system_file = install[system_prefix_len:]
+          # Not clear if collisions can ever happen in modules-info.json (e.g.
+          # the same file installed by multiple packages), but it doesn't hurt
+          # to check.
+          if system_file in system_files_to_package_map:
+            system_files_to_package_map[system_file] = "--multiple--"
+          else:
+            system_files_to_package_map[system_file] = module
+
+  return system_files_to_package_map
+
+def package_to_vendor_map(path):
+  """Returns a dictionary mapping from each package in modules-info.json to its
+  vendor. If a vendor cannot be found, it maps to "--unknown--". Those cases
+  are:
+
+    1. The package maps to multiple modules (e.g., one in APPS and one in
+       SHARED_LIBRARIES.
+    2. The path to the module is not one of the recognized vendor paths in
+       VENDOR_PATH_MAP."""
+  package_vendor_map = {}
+  system_prefix = os.path.join(path, 'system')
+  # Skip trailing '/'
+  system_prefix_len = len(system_prefix) + 1
+  vendor_prefixes = VENDOR_PATH_MAP.keys()
+
+  with open(os.path.join(path, 'module-info.json')) as module_info_json:
+    module_info = json.load(module_info_json)
+    for module in module_info:
+      paths = module_info[module]['path']
+      vendor = ""
+      if len(paths) == 1:
+        path = paths[0]
+        for prefix in vendor_prefixes:
+          if path.startswith(prefix):
+            vendor = VENDOR_PATH_MAP[prefix]
+            break
+        if vendor == "":
+          vendor = "--unknown--"
+      else:
+        vendor = "--multiple--"
+      package_vendor_map[module] = vendor
+
+  return package_vendor_map
+
+def main():
+  parser = argparse.ArgumentParser(description=HELP_MSG)
+  parser.add_argument("out1", help="First $OUT directory")
+  parser.add_argument("out2", help="Second $OUT directory")
+  args = parser.parse_args()
+
+  system_files1 = system_files(args.out1)
+  system_files2 = system_files(args.out2)
+  system_files_diff = set(system_files1) - set(system_files2)
+
+  system_files_map = system_files_to_package_map(args.out1)
+  package_vendor_map = package_to_vendor_map(args.out1)
+  packages = {}
+
+  for file in system_files_diff:
+    if file in system_files_map:
+      package = system_files_map[file]
+    else:
+      package = "--unknown--"
+
+    if package in packages:
+      packages[package].append(file)
+    else:
+      packages[package] = [file]
+
+  writer = csv.writer(sys.stdout, quoting = csv.QUOTE_NONNUMERIC,
+                      delimiter = ',', lineterminator = '\n')
+  for package, files in packages.items():
+    for file in files:
+      if package in package_vendor_map:
+        vendor = package_vendor_map[package]
+      else:
+        vendor = "--unknown--"
+      # Get file size
+      full_path = os.path.join(args.out1, 'system', file)
+      size = os.stat(full_path).st_size
+      writer.writerow([vendor, package, file, size])
+
+if __name__ == '__main__':
+  main()