diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
index 0ed230c..8a8df36 100644
--- a/PREUPLOAD.cfg
+++ b/PREUPLOAD.cfg
@@ -1,3 +1,4 @@
 [Hook Scripts]
 check_generated_files_up_to_date = tools/cpp-define-generator/presubmit-check-files-up-to-date
+check_generated_tests_up_to_date = tools/test_presubmit.py
 check_cpplint_on_changed_files = tools/cpplint_presubmit.py
diff --git a/tools/test_presubmit.py b/tools/test_presubmit.py
new file mode 100755
index 0000000..f6e6df9
--- /dev/null
+++ b/tools/test_presubmit.py
@@ -0,0 +1,159 @@
+#!/usr/bin/python3
+#
+# Copyright 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.
+
+#
+# There are many run-tests which generate their sources automatically.
+# It is desirable to keep the checked-in source code, as we re-run generators very rarely.
+#
+# This script will re-run the generators only if their dependent files have changed and then
+# complain if the outputs no longer matched what's in the source tree.
+#
+
+import os
+import pathlib
+import subprocess
+import sys
+import tempfile
+
+THIS_PATH = os.path.dirname(os.path.realpath(__file__))
+
+TOOLS_GEN_SRCS = [
+    # tool -> path to a script to generate a file
+    # reference_files -> list of files that the script can generate
+    # args -> lambda(path) that generates arguments the 'tool' in order to output to 'path'
+    # interesting_files -> which files much change in order to re-run the tool.
+    # interesting_to_reference_files: lambda(x,reference_files)
+    #                                 given the interesting file 'x' and a list of reference_files,
+    #                                 return exactly one reference file that corresponds to it.
+    { 'tool' : 'test/988-method-trace/gen_srcs.py',
+      'reference_files' : ['test/988-method-trace/src/art/Test988Intrinsics.java'],
+      'args' : lambda output_path: [output_path],
+      'interesting_files' : ['compiler/intrinsics_list.h'],
+      'interesting_to_reference_file' : lambda interesting, references: references[0],
+    },
+]
+
+DEBUG = False
+
+def debug_print(msg):
+  if DEBUG:
+    print("[DEBUG]: " + msg, file=sys.stderr)
+
+def is_interesting(f, tool_dict):
+  """
+  Returns true if this is a file we want to run this tool before uploading. False otherwise.
+  """
+  path = pathlib.Path(f)
+  return str(path) in tool_dict['interesting_files']
+
+def get_changed_files(commit):
+  """
+  Gets the files changed in the given commit.
+  """
+  return subprocess.check_output(
+      ["git", 'diff-tree', '--no-commit-id', '--name-only', '-r', commit],
+      stderr=subprocess.STDOUT,
+      universal_newlines=True).split()
+
+def command_line_for_tool(tool_dict, output):
+  """
+  Calculate the command line for this tool when ran against the output file 'output'.
+  """
+  proc_args = [tool_dict['tool']] + tool_dict['args'](output)
+  return proc_args
+
+def run_tool(tool_dict, output):
+  """
+  Execute this tool by passing the tool args to the tool.
+  """
+  proc_args = command_line_for_tool(tool_dict, output)
+  debug_print("PROC_ARGS: %s" %(proc_args))
+  succ = subprocess.call(proc_args)
+  return succ
+
+def get_reference_file(changed_file, tool_dict):
+   """
+   Lookup the file that the tool is generating in response to changing an interesting file
+   """
+   return tool_dict['interesting_to_reference_file'](changed_file, tool_dict['reference_files'])
+
+def run_diff(changed_file, tool_dict, original_file):
+  ref_file = get_reference_file(changed_file, tool_dict)
+
+  return subprocess.call(["diff", ref_file, original_file]) != 0
+
+def run_gen_srcs(files):
+  """
+  Runs test tools only for interesting files that were changed in this commit.
+  """
+  if len(files) == 0:
+    return
+
+  success = 0  # exit code 0 = success, >0 error.
+  had_diffs = False
+
+  for tool_dict in TOOLS_GEN_SRCS:
+    tool_ran_at_least_once = False
+    for f in files:
+      if is_interesting(f, tool_dict):
+        tmp_file = tempfile.mktemp()
+        reference_file = get_reference_file(f, tool_dict)
+
+        # Generate the source code with a temporary file as the output.
+        success = run_tool(tool_dict, tmp_file)
+        if success != 0:
+          # Immediately abort if the tool fails with a non-0 exit code, do not go any further.
+          print("[FATAL] Error when running tool (return code %s)" %(success), file=sys.stderr)
+          print("$> %s" %(" ".join(command_line_for_tool(tool_dict, tmp_file))), file=sys.stderr)
+          sys.exit(success)
+        if run_diff(f, tool_dict, tmp_file):
+          # If the tool succeeded, but there was a diff, then the generated code has diverged.
+          # Output the diff information and continue to the next files/tools.
+          had_diffs = True
+          print("-----------------------------------------------------------", file=sys.stderr)
+          print("File '%s' diverged from generated file; please re-run tools:" %(reference_file), file=sys.stderr)
+          print("$> %s" %(" ".join(command_line_for_tool(tool_dict, reference_file))), file=sys.stderr)
+        else:
+          debug_print("File %s is consistent with tool %s" %(reference_file, tool_dict['tool']))
+
+        tool_ran_at_least_once = True
+
+    if not tool_ran_at_least_once:
+      debug_print("Interesting files %s unchanged, skipping tool '%s'" %(tool_dict['interesting_files'], tool_dict['tool']))
+
+  if had_diffs:
+    success = 1
+  # Always return non-0 exit code when there were diffs so that the presubmit hooks are FAILED.
+
+  return success
+
+
+def main():
+  if 'PREUPLOAD_COMMIT' in os.environ:
+    commit = os.environ['PREUPLOAD_COMMIT']
+  else:
+    print("WARNING: Not running as a pre-upload hook. Assuming commit to check = 'HEAD'", file=sys.stderr)
+    commit = "HEAD"
+
+  os.chdir(os.path.join(THIS_PATH, '..')) # run tool relative to 'art' directory
+  debug_print("CWD: %s" %(os.getcwd()))
+
+  changed_files = get_changed_files(commit)
+  debug_print("Changed files: %s" %(changed_files))
+  return run_gen_srcs(changed_files)
+
+if __name__ == '__main__':
+  sys.exit(main())