diff --git a/tools/run_tests/filter_pull_request_tests.py b/tools/run_tests/filter_pull_request_tests.py
new file mode 100644
index 00000000000..6cc06d9c409
--- /dev/null
+++ b/tools/run_tests/filter_pull_request_tests.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python2.7
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Filter out tests based on file differences compared to grpc:master"""
+
+from subprocess import call, check_output
+
+# triggers to skip c++ tests
+run_cpp_starts_with_triggers = ('src/core',
+			        'src/cpp',
+			        'test/core',
+			        'test/cpp')
+
+
+def _get_changed_files():
+  """
+  Get list of changed files between current branch and gRPC master branch
+  """
+  # git fetch might need to be called on Jenkins slave
+  # todo(mattkwong): remove or uncomment below after seeing if Jenkins needs this
+  # call(['git', 'fetch'])
+  # this also collects files that are changed in the repo but not updated in the branch
+  return check_output(["git", "diff", "--name-only", "..origin/master"]).split()
+
+
+def _can_skip_tests(file_names, starts_with_triggers=(), ends_with_triggers=()):
+  """
+  Determines if tests are skippable based on if all file names do not match
+  any begin or end triggers
+  :param file_names: list of changed files generated by _get_changed_files()
+  :param starts_with_triggers: tuple of strings to match with beginning of file names
+  :param ends_with_triggers: tuple of strings to match with end of file names
+  :return: safe to skip tests
+  """
+  for file_name in file_names:
+    if starts_with_triggers and file_name.startswith(starts_with_triggers) or \
+       ends_with_triggers and file_name.endswith(ends_with_triggers):
+         return False
+  return True
+
+
+def _remove_irrelevant_tests(tests, tag):
+  """
+  Filters out tests by config or language
+  :param tests: list of all tests generated by run_tests_matrix.py
+  :param tag: string representing language or config to filter - "_(language)_" or "_(config)"
+  :return: list of relevant tests
+  """
+  return [test for test in tests if not tag in test.shortname]
+
+
+def filter_tests(tests):
+  """
+  Filters out tests that are safe to ignore
+  :param tests: list of all tests generated by run_tests_matrix.py
+  :return: list of relevant tests
+  """
+  print("Finding file differences between grpc:master repo and pull request...")
+  changed_files = _get_changed_files()
+  for changed_file in changed_files:
+    print(changed_file)
+  # C++, tsan, msan, and asan have the same filter
+  if _can_skip_tests(changed_files, starts_with_triggers=run_cpp_starts_with_triggers):
+    tests = _remove_irrelevant_tests(tests, '_c++_') # filter out c++ tests
+    tests = _remove_irrelevant_tests(tests, '_tsan') # filter out tsan tests
+    tests = _remove_irrelevant_tests(tests, '_msan') # filter out msan tests
+    tests = _remove_irrelevant_tests(tests, '_asan') # filter out asan tests
+  return tests
diff --git a/tools/run_tests/run_tests_matrix.py b/tools/run_tests/run_tests_matrix.py
index 60c21a1e218..235bd162be0 100755
--- a/tools/run_tests/run_tests_matrix.py
+++ b/tools/run_tests/run_tests_matrix.py
@@ -36,6 +36,7 @@ import multiprocessing
 import os
 import report_utils
 import sys
+from filter_pull_request_tests import filter_tests
 
 _ROOT = os.path.abspath(os.path.join(os.path.dirname(sys.argv[0]), '../..'))
 os.chdir(_ROOT)
@@ -231,6 +232,11 @@ argp.add_argument('--dry_run',
                   action='store_const',
                   const=True,
                   help='Only print what would be run.')
+argp.add_argument('--filter_pr_tests',
+	          default=False,
+		  action='store_const',	
+		  const=True,	  
+		  help='Filters out tests irrelavant to pull request changes.')
 args = argp.parse_args()
 
 extra_args = []
@@ -264,6 +270,18 @@ for job in jobs:
     print '  %s' % job.shortname
 print
 
+if args.filter_pr_tests:
+  print 'IMPORTANT: Test filtering is not active; this is only for testing.'
+  relevant_jobs = filter_tests(jobs)
+  print
+  if len(relevant_jobs) == len(jobs):
+    print 'No tests were filtered.'
+  else:
+    print 'These tests were filtered:'
+    for job in list(set(jobs) - set(relevant_jobs)):
+      print '  %s' % job.shortname
+  print
+
 if args.dry_run:
   print '--dry_run was used, exiting'
   sys.exit(1)