Index: test/CMakeLists.txt
===================================================================
--- test/CMakeLists.txt
+++ test/CMakeLists.txt
@@ -118,6 +118,11 @@
     )
 endif()
 
+option(LLVM_XFAILS_REQUIRE_PRS "Require PRs for all tests with XFAIL annotations" Off)
+if(LLVM_XFAILS_REQUIRE_PRS)
+  list(APPEND LLVM_LIT_ARGS "--xfail-requires-pr")
+endif()
+
 add_custom_target(llvm-test-depends DEPENDS ${LLVM_TEST_DEPENDS})
 set_target_properties(llvm-test-depends PROPERTIES FOLDER "Tests")
 
Index: test/ExecutionEngine/MCJIT/stubs-sm-pic.ll
===================================================================
--- test/ExecutionEngine/MCJIT/stubs-sm-pic.ll
+++ test/ExecutionEngine/MCJIT/stubs-sm-pic.ll
@@ -1,5 +1,5 @@
 ; RUN: %lli -disable-lazy-compilation=false -relocation-model=pic -code-model=small %s
-; XFAIL: mips-, mipsel-, i686, i386, aarch64, arm
+; XFAIL: mips-, mipsel-, i686, i386, aarch64, arm, http://llvm.org/PR12345
 
 define i32 @main() nounwind {
 entry:
Index: utils/lit/lit/LitConfig.py
===================================================================
--- utils/lit/lit/LitConfig.py
+++ utils/lit/lit/LitConfig.py
@@ -24,7 +24,9 @@
                  noExecute, debug, isWindows,
                  params, config_prefix = None,
                  maxIndividualTestTime = 0,
-                 maxFailures = None):
+                 maxFailures = None,
+                 xFailRequirePR = False,
+                 bugTrackerRegex = None):
         # The name of the test runner.
         self.progname = progname
         # The items to add to the PATH environment variable.
@@ -62,6 +64,8 @@
 
         self.maxIndividualTestTime = maxIndividualTestTime
         self.maxFailures = maxFailures
+        self.xFailRequirePR = xFailRequirePR
+        self.bugTrackerRegex = bugTrackerRegex
 
     @property
     def maxIndividualTestTime(self):
Index: utils/lit/lit/Test.py
===================================================================
--- utils/lit/lit/Test.py
+++ utils/lit/lit/Test.py
@@ -34,6 +34,7 @@
 UNRESOLVED  = ResultCode('UNRESOLVED', True)
 UNSUPPORTED = ResultCode('UNSUPPORTED', False)
 TIMEOUT     = ResultCode('TIMEOUT', True)
+UNXFAIL     = ResultCode('UNXFAIL', False)
 
 # Test metric values.
 
@@ -183,7 +184,7 @@
         # A list of conditions under which this test is expected to fail. These
         # can optionally be provided by test format handlers, and will be
         # honored when the test result is supplied.
-        self.xfails = []
+        self.xfails = {}
         # The test result, once complete.
         self.result = None
 
@@ -201,6 +202,8 @@
                 self.result.code = XPASS
             elif self.result.code == FAIL:
                 self.result.code = XFAIL
+            elif self.result.code == UNXFAIL:
+                self.result.code = FAIL
         
     def getFullName(self):
         return self.suite.config.name + ' :: ' + '/'.join(self.path_in_suite)
@@ -227,17 +230,17 @@
         """
 
         # Check if any of the xfails match an available feature or the target.
-        for item in self.xfails:
+        for feature, pr in self.xfails.iteritems():
             # If this is the wildcard, it always fails.
-            if item == '*':
+            if feature == '*':
                 return True
 
             # If this is an exact match for one of the features, it fails.
-            if item in self.config.available_features:
+            if feature in self.config.available_features:
                 return True
 
             # If this is a part of the target triple, it fails.
-            if item and item in self.suite.config.target_triple:
+            if feature and feature in self.suite.config.target_triple:
                 return True
 
         return False
Index: utils/lit/lit/TestRunner.py
===================================================================
--- utils/lit/lit/TestRunner.py
+++ utils/lit/lit/TestRunner.py
@@ -672,7 +672,7 @@
     # convert to list before returning.
     return list(map(processLine, script))
 
-def parseIntegratedTestScript(test, require_script=True):
+def parseIntegratedTestScript(test, require_script=True, xFailRequirePR=False, bugTrackerRegex=None):
     """parseIntegratedTestScript - Scan an LLVM/Clang style integrated test
     script and extract the lines to 'RUN' as well as 'XFAIL' and 'REQUIRES'
     and 'UNSUPPORTED' information. If 'require_script' is False an empty script
@@ -708,7 +708,16 @@
             else:
                 script.append(ln)
         elif command_type == 'XFAIL':
-            test.xfails.extend([s.strip() for s in ln.split(',')])
+            xfail_prs = [s.strip() for s in ln.split(',') if bugTrackerRegex.match(s.strip())]
+            if len(xfail_prs) > 1:
+                raise ValueError("XFAIL command cannot have more than one PR, "
+                                 "use multiple xfail commands.")
+            xfail_pr = None
+            if(len(xfail_prs) > 0):
+                xfail_pr = xfail_prs[0]
+            xfail_features = [s.strip() for s in ln.split(',') if not bugTrackerRegex.match(s.strip())]
+            for feature in xfail_features:
+                test.xfails[feature] = xfail_pr
         elif command_type == 'REQUIRES':
             requires.extend([s.strip() for s in ln.split(',')])
         elif command_type == 'REQUIRES-ANY':
@@ -768,6 +777,11 @@
             return lit.Test.Result(Test.UNSUPPORTED,
                  "Test requires one of the limit_to_features features %s" % msg)
 
+    if xFailRequirePR:
+        for feature, pr in test.xfails.iteritems():
+            if pr is None:
+                return lit.Test.Result(Test.UNXFAIL, "XFAIL command missing PR")
+
     return script
 
 def _runShTest(test, litConfig, useExternalSh, script, tmpBase):
@@ -813,7 +827,9 @@
     if test.config.unsupported:
         return (Test.UNSUPPORTED, 'Test is unsupported')
 
-    script = parseIntegratedTestScript(test)
+    script = parseIntegratedTestScript(test,
+                                       xFailRequirePR=litConfig.xFailRequirePR,
+                                       bugTrackerRegex=litConfig.bugTrackerRegex)
     if isinstance(script, lit.Test.Result):
         return script
     if litConfig.noExecute:
Index: utils/lit/lit/main.py
===================================================================
--- utils/lit/lit/main.py
+++ utils/lit/lit/main.py
@@ -273,6 +273,14 @@
     group.add_option("", "--use-threads", dest="useProcesses",
                       help="Run tests in parallel with threads (not processes)",
                       action="store_false", default=True)
+    group.add_option("", "--xfail-requires-pr", dest="xFailRequirePR",
+                      help="Require PRs for XFAIL tests",
+                      action="store_true", default=False)
+    parser.add_option("", "--bug-tracker-prefix", dest="bugTrackerPrefixes",
+                      metavar="",
+                      help=("Prefixes for specifying bugs in XFAIL directives "
+                            "(defaults to include http://llvm.org/PR)"),
+                      type=str, action="append", default=['http://llvm.org/PR'])
     parser.add_option_group(group)
 
     (opts, args) = parser.parse_args()
@@ -316,6 +324,7 @@
         maxIndividualTestTime = 0
 
     isWindows = platform.system() == 'Windows'
+    bugTrackerRegex = re.compile('^' + '|^'.join(opts.bugTrackerPrefixes))
 
     # Create the global config object.
     litConfig = lit.LitConfig.LitConfig(
@@ -331,7 +340,9 @@
         params = userParams,
         config_prefix = opts.configPrefix,
         maxIndividualTestTime = maxIndividualTestTime,
-        maxFailures = opts.maxFailures)
+        maxFailures = opts.maxFailures,
+        xFailRequirePR = opts.xFailRequirePR,
+        bugTrackerRegex = bugTrackerRegex)
 
     # Perform test discovery.
     run = lit.run.Run(litConfig,
Index: utils/lit/tests/Inputs/xfail-require-pr/lit.cfg
===================================================================
--- /dev/null
+++ utils/lit/tests/Inputs/xfail-require-pr/lit.cfg
@@ -0,0 +1,7 @@
+import lit.formats
+config.name = 'xfail-requires-pr'
+config.suffixes = ['.txt']
+config.test_format = lit.formats.ShTest()
+config.test_source_root = None
+config.test_exec_root = None
+config.target_triple = 'x86_64-unknown-unknown'
Index: utils/lit/tests/Inputs/xfail-require-pr/xfail-containing-custom-pr.txt
===================================================================
--- /dev/null
+++ utils/lit/tests/Inputs/xfail-require-pr/xfail-containing-custom-pr.txt
@@ -0,0 +1,2 @@
+RUN: false
+XFAIL: *, http://foo.org/PR123
Index: utils/lit/tests/Inputs/xfail-require-pr/xfail-containing-pr.txt
===================================================================
--- /dev/null
+++ utils/lit/tests/Inputs/xfail-require-pr/xfail-containing-pr.txt
@@ -0,0 +1,2 @@
+RUN: false
+XFAIL: *, http://llvm.org/PR123
Index: utils/lit/tests/Inputs/xfail-require-pr/xfail-missing-pr.txt
===================================================================
--- /dev/null
+++ utils/lit/tests/Inputs/xfail-require-pr/xfail-missing-pr.txt
@@ -0,0 +1,2 @@
+RUN: false
+XFAIL: *
Index: utils/lit/tests/xfail-require-pr.py
===================================================================
--- /dev/null
+++ utils/lit/tests/xfail-require-pr.py
@@ -0,0 +1,20 @@
+# RUN: %{lit} -j 1 -v %{inputs}/xfail-require-pr | FileCheck --check-prefix=DEFAULT %s
+# DEFAULT: XFAIL: xfail-requires-pr :: xfail-containing-custom-pr.txt (1 of 3)
+# DEFAULT: XFAIL: xfail-requires-pr :: xfail-containing-pr.txt (2 of 3)
+# DEFAULT: XFAIL: xfail-requires-pr :: xfail-missing-pr.txt (3 of 3)
+# DEFAULT: Expected Failures  : 3
+
+
+# RUN: not %{lit} -j 1 -v %{inputs}/xfail-require-pr --xfail-requires-pr | FileCheck --check-prefix=REQUIRE_PR %s
+# REQUIRE_PR: FAIL: xfail-requires-pr :: xfail-containing-custom-pr.txt (1 of 3)
+# REQUIRE_PR: XFAIL: xfail-requires-pr :: xfail-containing-pr.txt (2 of 3)
+# REQUIRE_PR: FAIL: xfail-requires-pr :: xfail-missing-pr.txt (3 of 3)
+# REQUIRE_PR: Expected Failures  : 1
+# REQUIRE_PR: Unexpected Failures: 2
+
+# RUN: not %{lit} -j 1 -v %{inputs}/xfail-require-pr --xfail-requires-pr --bug-tracker-prefix http://foo.org/ | FileCheck --check-prefix=CUSTOM_PR %s
+# CUSTOM_PR: XFAIL: xfail-requires-pr :: xfail-containing-custom-pr.txt (1 of 3)
+# CUSTOM_PR: XFAIL: xfail-requires-pr :: xfail-containing-pr.txt (2 of 3)
+# CUSTOM_PR: FAIL: xfail-requires-pr :: xfail-missing-pr.txt (3 of 3)
+# CUSTOM_PR: Expected Failures  : 2
+# CUSTOM_PR: Unexpected Failures: 1