Index: utils/lit/lit/LitConfig.py
===================================================================
--- utils/lit/lit/LitConfig.py
+++ utils/lit/lit/LitConfig.py
@@ -21,7 +21,7 @@
     def __init__(self, progname, path, quiet,
                  useValgrind, valgrindLeakCheck, valgrindArgs,
                  noExecute, debug, isWindows,
-                 params, config_prefix = None):
+                 params, config_prefix = None, timeout = None):
         # The name of the test runner.
         self.progname = progname
         # The items to add to the PATH environment variable.
@@ -57,6 +57,7 @@
                 self.valgrindArgs.append('--leak-check=no')
             self.valgrindArgs.extend(self.valgrindUserArgs)
 
+        self.timeout = timeout
 
     def load_config(self, config, path):
         """load_config(config, path) - Load a config object from an alternate
Index: utils/lit/lit/TestRunner.py
===================================================================
--- utils/lit/lit/TestRunner.py
+++ utils/lit/lit/TestRunner.py
@@ -33,28 +33,28 @@
         self.cwd = cwd
         self.env = env
 
-def executeShCmd(cmd, shenv, results):
+def executeShCmd(cmd, shenv, results, watchdog=None):
     if isinstance(cmd, ShUtil.Seq):
         if cmd.op == ';':
-            res = executeShCmd(cmd.lhs, shenv, results)
-            return executeShCmd(cmd.rhs, shenv, results)
+            res = executeShCmd(cmd.lhs, shenv, results, watchdog)
+            return executeShCmd(cmd.rhs, shenv, results, watchdog)
 
         if cmd.op == '&':
             raise InternalShellError(cmd,"unsupported shell operator: '&'")
 
         if cmd.op == '||':
-            res = executeShCmd(cmd.lhs, shenv, results)
+            res = executeShCmd(cmd.lhs, shenv, results, watchdog)
             if res != 0:
-                res = executeShCmd(cmd.rhs, shenv, results)
+                res = executeShCmd(cmd.rhs, shenv, results, watchdog)
             return res
 
         if cmd.op == '&&':
-            res = executeShCmd(cmd.lhs, shenv, results)
+            res = executeShCmd(cmd.lhs, shenv, results, watchdog)
             if res is None:
                 return res
 
             if res == 0:
-                res = executeShCmd(cmd.rhs, shenv, results)
+                res = executeShCmd(cmd.rhs, shenv, results, watchdog)
             return res
 
         raise ValueError('Unknown shell command: %r' % cmd.op)
@@ -171,13 +171,16 @@
                     args[i] = f.name
 
         try:
-            procs.append(subprocess.Popen(args, cwd=shenv.cwd,
-                                          executable = executable,
-                                          stdin = stdin,
-                                          stdout = stdout,
-                                          stderr = stderr,
-                                          env = shenv.env,
-                                          close_fds = kUseCloseFDs))
+            p = subprocess.Popen(args, cwd=shenv.cwd,
+                                 executable = executable,
+                                 stdin = stdin,
+                                 stdout = stdout,
+                                 stderr = stderr,
+                                 env = shenv.env,
+                                 close_fds = kUseCloseFDs)
+            procs.append(p)
+            if watchdog is not None:
+                watchdog.watch(p)
         except OSError as e:
             raise InternalShellError(j, 'Could not create process due to {}'.format(e))
 
@@ -281,9 +284,14 @@
         cmd = ShUtil.Seq(cmd, '&&', c)
 
     results = []
+    wd = None
     try:
+        if litConfig.timeout is not None:
+            wd = lit.util.Watchdog(litConfig.timeout)
         shenv = ShellEnvironment(cwd, test.config.environment)
-        exitCode = executeShCmd(cmd, shenv, results)
+        exitCode = executeShCmd(cmd, shenv, results, wd)
+        if wd is not None:
+            wd.cancel()
     except InternalShellError:
         e = sys.exc_info()[1]
         exitCode = 127
@@ -296,6 +304,9 @@
         out += 'Command %d Output:\n%s\n\n' % (i, cmd_out)
         out += 'Command %d Stderr:\n%s\n\n' % (i, cmd_err)
 
+    if wd is not None and wd.timed_out:
+        out += "\n\nTimed out after %.2f seconds" % (litConfig.timeout)
+
     return out, err, exitCode
 
 def executeScript(test, litConfig, tmpBase, commands, cwd):
@@ -332,7 +343,8 @@
             command = litConfig.valgrindArgs + command
 
     return lit.util.executeCommand(command, cwd=cwd,
-                                   env=test.config.environment)
+                                   env=test.config.environment,
+                                   timeout=litConfig.timeout)
 
 def parseIntegratedTestScriptCommands(source_path):
     """
Index: utils/lit/lit/formats/base.py
===================================================================
--- utils/lit/lit/formats/base.py
+++ utils/lit/lit/formats/base.py
@@ -101,7 +101,7 @@
         else:
             cmd.append(test.getSourcePath())
 
-        out, err, exitCode = lit.util.executeCommand(cmd)
+        out, err, exitCode = lit.util.executeCommand(cmd, timeout=litConfig.timeout)
 
         diags = out + err
         if not exitCode and not diags.strip():
Index: utils/lit/lit/main.py
===================================================================
--- utils/lit/lit/main.py
+++ utils/lit/lit/main.py
@@ -208,6 +208,9 @@
     group.add_option("", "--max-time", dest="maxTime", metavar="N",
                      help="Maximum time to spend testing (in seconds)",
                      action="store", type=float, default=None)
+    group.add_option("", "--timeout", dest="timeout", metavar="N",
+                     help="Maximum time to spend in any given test (in seconds)",
+                     action="store", type=float, default=None)
     group.add_option("", "--shuffle", dest="shuffle",
                      help="Run tests in random order",
                      action="store_true", default=False)
@@ -281,7 +284,8 @@
         debug = opts.debug,
         isWindows = isWindows,
         params = userParams,
-        config_prefix = opts.configPrefix)
+        config_prefix = opts.configPrefix,
+        timeout = opts.timeout)
 
     # Perform test discovery.
     run = lit.run.Run(litConfig,
Index: utils/lit/lit/util.py
===================================================================
--- utils/lit/lit/util.py
+++ utils/lit/lit/util.py
@@ -6,7 +6,46 @@
 import signal
 import subprocess
 import sys
+import threading
 
+class Watchdog(object):
+    """
+    Watches a Popen call, and kills it after a timeout.
+    """
+    def __init__(self, timeout):
+        self.popens = []
+        self.timed_out = False
+        self.timer = threading.Timer(timeout, self.handler)
+        self.timer.start()
+
+    def _safely_kill(self, popen):
+        if popen.poll() is None:
+            try:
+                popen.kill()
+            except OSError, e:
+                # The popen terminated or was killed by something else between
+                # the test above and when kill was called... either way we got
+                # what we wanted.
+                pass
+
+    def handler(self):
+        self.timed_out = True
+        for popen in self.popens:
+            self._safely_kill(popen)
+
+    def watch(self, popen):
+        self.popens.append(popen)
+
+        # Take care of the race condition where the timer timed out before the
+        # popen was added to the list.
+        if self.timed_out:
+            self._safely_kill(popen)
+
+    def cancel(self):
+        if self.timer is not None:
+            self.timer.cancel()
+
+
 def to_bytes(str):
     # Encode to UTF-8 to get binary data.
     return str.encode('utf-8')
@@ -158,15 +197,25 @@
 # Close extra file handles on UNIX (on Windows this cannot be done while
 # also redirecting input).
 kUseCloseFDs = not (platform.system() == 'Windows')
-def executeCommand(command, cwd=None, env=None):
+def executeCommand(command, cwd=None, env=None, timeout=None):
     p = subprocess.Popen(command, cwd=cwd,
                          stdin=subprocess.PIPE,
                          stdout=subprocess.PIPE,
                          stderr=subprocess.PIPE,
                          env=env, close_fds=kUseCloseFDs)
+
+    if timeout is not None:
+        wd = Watchdog(timeout)
+        wd.watch(p)
+
     out,err = p.communicate()
     exitCode = p.wait()
 
+    if timeout is not None:
+        wd.cancel()
+        if wd.timed_out:
+            err += "\n\nTimed out after %.2f seconds" % (timeout)
+
     # Detect Ctrl-C in subprocess.
     if exitCode == -signal.SIGINT:
         raise KeyboardInterrupt
Index: utils/lit/tests/Inputs/timeout/infloop.py
===================================================================
--- utils/lit/tests/Inputs/timeout/infloop.py
+++ utils/lit/tests/Inputs/timeout/infloop.py
@@ -0,0 +1,8 @@
+# RUN: %{python} %s
+# XFAIL: *
+
+import sys
+
+print "infinite loop"
+while True:
+    pass
Index: utils/lit/tests/Inputs/timeout/lit.cfg
===================================================================
--- utils/lit/tests/Inputs/timeout/lit.cfg
+++ utils/lit/tests/Inputs/timeout/lit.cfg
@@ -0,0 +1,16 @@
+# -*- Python -*-
+
+import os
+import sys
+
+import lit.formats
+
+config.name = 'timeout'
+config.test_format = lit.formats.ShTest(execute_external=False)
+config.suffixes = ['.py']
+config.test_source_root = os.path.dirname(__file__)
+config.test_exec_root = config.test_source_root
+config.target_triple = '(unused)'
+src_root = os.path.join(config.test_source_root, '..')
+config.environment['PYTHONPATH'] = src_root
+config.substitutions.append(('%{python}', sys.executable))
Index: utils/lit/tests/Inputs/timeout/short.py
===================================================================
--- utils/lit/tests/Inputs/timeout/short.py
+++ utils/lit/tests/Inputs/timeout/short.py
@@ -0,0 +1,5 @@
+# RUN: %{python} %s
+
+import sys
+
+print "short program"
Index: utils/lit/tests/timeout.py
===================================================================
--- utils/lit/tests/timeout.py
+++ utils/lit/tests/timeout.py
@@ -0,0 +1,9 @@
+# RUN: %{lit} \
+# RUN: %{inputs}/timeout/infloop.py \
+# RUN: %{inputs}/timeout/short.py \
+# RUN:   -j 1 -v --debug --timeout 0.1 > %t.out 2> %t.err
+# RUN: FileCheck --check-prefix=CHECK-OUT < %t.out %s
+#
+
+# CHECK-OUT: XFAIL: timeout :: infloop.py
+# CHECK-OUT: PASS: timeout :: short.py