diff --git a/run-tests.py b/run_tests.py
similarity index 74%
rename from run-tests.py
rename to run_tests.py
index 5eb73a1c1..bc988f15c 100755
--- a/run-tests.py
+++ b/run_tests.py
@@ -14,11 +14,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+"""Runs the libc++ tests against the platform libc++."""
 from __future__ import print_function
 
 import argparse
+import logging
 import os
-import subprocess
 import sys
 
 
@@ -26,7 +27,27 @@ THIS_DIR = os.path.dirname(os.path.realpath(__file__))
 ANDROID_DIR = os.path.realpath(os.path.join(THIS_DIR, '../..'))
 
 
+def logger():
+    """Returns the logger for the module."""
+    return logging.getLogger(__name__)
+
+
+def call(cmd, *args, **kwargs):
+    """subprocess.call with logging."""
+    import subprocess
+    logger().info('call %s', ' '.join(cmd))
+    return subprocess.call(cmd, *args, **kwargs)
+
+
+def check_call(cmd, *args, **kwargs):
+    """subprocess.check_call with logging."""
+    import subprocess
+    logger().info('check_call %s', ' '.join(cmd))
+    return subprocess.check_call(cmd, *args, **kwargs)
+
+
 class ArgParser(argparse.ArgumentParser):
+    """Parses command line arguments."""
     def __init__(self):
         super(ArgParser, self).__init__()
         self.add_argument(
@@ -37,6 +58,7 @@ class ArgParser(argparse.ArgumentParser):
 
 
 def gen_test_config(bitness, compiler, host):
+    """Generates the test configuration makefile for buildcmds."""
     testconfig_mk_path = os.path.join(THIS_DIR, 'buildcmds/testconfig.mk')
     with open(testconfig_mk_path, 'w') as test_config:
         if compiler == 'clang':
@@ -68,28 +90,38 @@ def gen_test_config(bitness, compiler, host):
 
 
 def mmm(path):
+    """Invokes the Android build command mmm."""
     makefile = os.path.join(path, 'Android.mk')
     main_mk = 'build/core/main.mk'
 
     env = dict(os.environ)
     env['ONE_SHOT_MAKEFILE'] = makefile
     env['LIBCXX_TESTING'] = 'true'
-    cmd = ['make', '-j', '-C', ANDROID_DIR, '-f', main_mk, 'MODULES-IN-' + path.replace('/','-')]
-    subprocess.check_call(cmd, env=env)
+    cmd = [
+        'make', '-j', '-C', ANDROID_DIR, '-f', main_mk,
+        'MODULES-IN-' + path.replace('/', '-'),
+    ]
+    check_call(cmd, env=env)
 
 
 def gen_build_cmds(bitness, compiler, host):
+    """Generates the build commands file for the test runner."""
     gen_test_config(bitness, compiler, host)
     mmm('external/libcxx/buildcmds')
 
 
 def main():
+    """Program entry point."""
+    logging.basicConfig(level=logging.INFO)
+
     args, lit_args = ArgParser().parse_known_args()
     lit_path = os.path.join(ANDROID_DIR, 'external/llvm/utils/lit/lit.py')
     gen_build_cmds(args.bitness, args.compiler, args.host)
 
     mode_str = 'host' if args.host else 'device'
     android_mode_arg = '--param=android_mode=' + mode_str
+    site_cfg_path = os.path.join(THIS_DIR, 'test/lit.site.cfg')
+    site_cfg_arg = '--param=libcxx_site_config=' + site_cfg_path
     default_test_path = os.path.join(THIS_DIR, 'test')
 
     have_filter_args = False
@@ -105,11 +137,11 @@ def main():
         have_filter_args = True
         break  # No need to keep scanning.
 
-    lit_args = ['-sv', android_mode_arg] + lit_args
+    lit_args = ['-sv', android_mode_arg, site_cfg_arg] + lit_args
     cmd = ['python', lit_path] + lit_args
     if not have_filter_args:
         cmd.append(default_test_path)
-    sys.exit(subprocess.call(cmd))
+    sys.exit(call(cmd))
 
 
 if __name__ == '__main__':