diff --git a/.vsts/linux-pr.yml b/.vsts/linux-pr.yml
index 6e4ac7c..d11a4f0 100644
--- a/.vsts/linux-pr.yml
+++ b/.vsts/linux-pr.yml
@@ -70,6 +70,15 @@
   displayName: 'Run patchcheck.py'
   condition: and(succeeded(), ne(variables['DocOnly'], 'true'))
 
-- script: xvfb-run make buildbottest TESTOPTS="-j4 -uall,-cpu"
+- script: xvfb-run make buildbottest TESTOPTS="-j4 -uall,-cpu --junit-xml=$(build.binariesDirectory)/test-results.xml"
   displayName: 'Tests'
   condition: and(succeeded(), ne(variables['DocOnly'], 'true'))
+
+- task: PublishTestResults@2
+  displayName: 'Publish Test Results'
+  inputs:
+    testResultsFiles: '$(build.binariesDirectory)/test-results.xml'
+    mergeTestResults: true
+    testRunTitle: '$(system.pullRequest.targetBranch)-linux'
+    platform: linux
+  condition: and(succeededOrFailed(), ne(variables['DocOnly'], 'true'))
diff --git a/.vsts/macos-pr.yml b/.vsts/macos-pr.yml
index c56e66b..69b619e 100644
--- a/.vsts/macos-pr.yml
+++ b/.vsts/macos-pr.yml
@@ -50,6 +50,15 @@
   displayName: 'Display build info'
   condition: and(succeeded(), ne(variables['DocOnly'], 'true'))
 
-- script: make buildbottest TESTOPTS="-j4 -uall,-cpu"
+- script: make buildbottest TESTOPTS="-j4 -uall,-cpu --junit-xml=$(build.binariesDirectory)/test-results.xml"
   displayName: 'Tests'
   condition: and(succeeded(), ne(variables['DocOnly'], 'true'))
+
+- task: PublishTestResults@2
+  displayName: 'Publish Test Results'
+  inputs:
+    testResultsFiles: '$(build.binariesDirectory)/test-results.xml'
+    mergeTestResults: true
+    testRunTitle: '$(system.pullRequest.targetBranch)-macOS'
+    platform: macOS
+  condition: and(succeededOrFailed(), ne(variables['DocOnly'], 'true'))
diff --git a/.vsts/windows-pr.yml b/.vsts/windows-pr.yml
index 3dd5609..7134120 100644
--- a/.vsts/windows-pr.yml
+++ b/.vsts/windows-pr.yml
@@ -54,8 +54,17 @@
   displayName: 'Display build info'
   condition: and(succeeded(), ne(variables['DocOnly'], 'true'))
 
-- script: PCbuild\rt.bat -q -uall -u-cpu -rwW --slowest --timeout=1200 -j0
+- script: PCbuild\rt.bat -q -uall -u-cpu -rwW --slowest --timeout=1200 -j0 --junit-xml="$(Build.BinariesDirectory)\test-results.xml"
   displayName: 'Tests'
   env:
     PREFIX: $(Py_OutDir)\$(outDirSuffix)
   condition: and(succeeded(), ne(variables['DocOnly'], 'true'))
+
+- task: PublishTestResults@2
+  displayName: 'Publish Test Results'
+  inputs:
+    testResultsFiles: '$(Build.BinariesDirectory)\test-results.xml'
+    mergeTestResults: true
+    testRunTitle: '$(System.PullRequest.TargetBranch)-$(outDirSuffix)'
+    platform: $(outDirSuffix)
+  condition: and(succeededOrFailed(), ne(variables['DocOnly'], 'true'))
diff --git a/Lib/test/eintrdata/eintr_tester.py b/Lib/test/eintrdata/eintr_tester.py
index bc308fe..1caeafe 100644
--- a/Lib/test/eintrdata/eintr_tester.py
+++ b/Lib/test/eintrdata/eintr_tester.py
@@ -52,7 +52,8 @@
 
         # Issue #25277: Use faulthandler to try to debug a hang on FreeBSD
         if hasattr(faulthandler, 'dump_traceback_later'):
-            faulthandler.dump_traceback_later(10 * 60, exit=True)
+            faulthandler.dump_traceback_later(10 * 60, exit=True,
+                                              file=sys.__stderr__)
 
     @classmethod
     def stop_alarm(cls):
diff --git a/Lib/test/libregrtest/cmdline.py b/Lib/test/libregrtest/cmdline.py
index bd126b3..538ff05 100644
--- a/Lib/test/libregrtest/cmdline.py
+++ b/Lib/test/libregrtest/cmdline.py
@@ -268,6 +268,10 @@
                        help='if a test file alters the environment, mark '
                             'the test as failed')
 
+    group.add_argument('--junit-xml', dest='xmlpath', metavar='FILENAME',
+                       help='writes JUnit-style XML results to the specified '
+                            'file')
+
     return parser
 
 
diff --git a/Lib/test/libregrtest/main.py b/Lib/test/libregrtest/main.py
index a176db5..1fd4132 100644
--- a/Lib/test/libregrtest/main.py
+++ b/Lib/test/libregrtest/main.py
@@ -100,8 +100,11 @@
         self.next_single_test = None
         self.next_single_filename = None
 
+        # used by --junit-xml
+        self.testsuite_xml = None
+
     def accumulate_result(self, test, result):
-        ok, test_time = result
+        ok, test_time, xml_data = result
         if ok not in (CHILD_ERROR, INTERRUPTED):
             self.test_times.append((test_time, test))
         if ok == PASSED:
@@ -118,6 +121,15 @@
         elif ok != INTERRUPTED:
             raise ValueError("invalid test result: %r" % ok)
 
+        if xml_data:
+            import xml.etree.ElementTree as ET
+            for e in xml_data:
+                try:
+                    self.testsuite_xml.append(ET.fromstring(e))
+                except ET.ParseError:
+                    print(xml_data, file=sys.__stderr__)
+                    raise
+
     def display_progress(self, test_index, test):
         if self.ns.quiet:
             return
@@ -164,6 +176,9 @@
                       file=sys.stderr)
                 ns.findleaks = False
 
+        if ns.xmlpath:
+            support.junit_xml_list = self.testsuite_xml = []
+
         # Strip .py extensions.
         removepy(ns.args)
 
@@ -384,7 +399,7 @@
                     result = runtest(self.ns, test)
                 except KeyboardInterrupt:
                     self.interrupted = True
-                    self.accumulate_result(test, (INTERRUPTED, None))
+                    self.accumulate_result(test, (INTERRUPTED, None, None))
                     break
                 else:
                     self.accumulate_result(test, result)
@@ -508,6 +523,31 @@
         if self.ns.runleaks:
             os.system("leaks %d" % os.getpid())
 
+    def save_xml_result(self):
+        if not self.ns.xmlpath and not self.testsuite_xml:
+            return
+
+        import xml.etree.ElementTree as ET
+        root = ET.Element("testsuites")
+
+        # Manually count the totals for the overall summary
+        totals = {'tests': 0, 'errors': 0, 'failures': 0}
+        for suite in self.testsuite_xml:
+            root.append(suite)
+            for k in totals:
+                try:
+                    totals[k] += int(suite.get(k, 0))
+                except ValueError:
+                    pass
+
+        for k, v in totals.items():
+            root.set(k, str(v))
+
+        xmlpath = os.path.join(support.SAVEDCWD, self.ns.xmlpath)
+        with open(xmlpath, 'wb') as f:
+            for s in ET.tostringlist(root):
+                f.write(s)
+
     def main(self, tests=None, **kwargs):
         global TEMPDIR
 
@@ -570,6 +610,9 @@
             self.rerun_failed_tests()
 
         self.finalize()
+
+        self.save_xml_result()
+
         if self.bad:
             sys.exit(2)
         if self.interrupted:
diff --git a/Lib/test/libregrtest/runtest.py b/Lib/test/libregrtest/runtest.py
index 3e1afd4..4f41080 100644
--- a/Lib/test/libregrtest/runtest.py
+++ b/Lib/test/libregrtest/runtest.py
@@ -85,8 +85,8 @@
     ns -- regrtest namespace of options
     test -- the name of the test
 
-    Returns the tuple (result, test_time), where result is one of the
-    constants:
+    Returns the tuple (result, test_time, xml_data), where result is one
+    of the constants:
 
         INTERRUPTED      KeyboardInterrupt when run under -j
         RESOURCE_DENIED  test skipped because resource denied
@@ -94,6 +94,9 @@
         ENV_CHANGED      test failed because it changed the execution environment
         FAILED           test failed
         PASSED           test passed
+
+    If ns.xmlpath is not None, xml_data is a list containing each
+    generated testsuite element.
     """
 
     output_on_failure = ns.verbose3
@@ -106,22 +109,13 @@
         # reset the environment_altered flag to detect if a test altered
         # the environment
         support.environment_altered = False
+        support.junit_xml_list = xml_list = [] if ns.xmlpath else None
         if ns.failfast:
             support.failfast = True
         if output_on_failure:
             support.verbose = True
 
-            # Reuse the same instance to all calls to runtest(). Some
-            # tests keep a reference to sys.stdout or sys.stderr
-            # (eg. test_argparse).
-            if runtest.stringio is None:
-                stream = io.StringIO()
-                runtest.stringio = stream
-            else:
-                stream = runtest.stringio
-                stream.seek(0)
-                stream.truncate()
-
+            stream = io.StringIO()
             orig_stdout = sys.stdout
             orig_stderr = sys.stderr
             try:
@@ -138,12 +132,18 @@
         else:
             support.verbose = ns.verbose  # Tell tests to be moderately quiet
             result = runtest_inner(ns, test, display_failure=not ns.verbose)
-        return result
+
+        if xml_list:
+            import xml.etree.ElementTree as ET
+            xml_data = [ET.tostring(x).decode('us-ascii') for x in xml_list]
+        else:
+            xml_data = None
+        return result + (xml_data,)
     finally:
         if use_timeout:
             faulthandler.cancel_dump_traceback_later()
         cleanup_test_droppings(test, ns.verbose)
-runtest.stringio = None
+        support.junit_xml_list = None
 
 
 def post_test_cleanup():
diff --git a/Lib/test/libregrtest/runtest_mp.py b/Lib/test/libregrtest/runtest_mp.py
index 1f07cfb..6190574 100644
--- a/Lib/test/libregrtest/runtest_mp.py
+++ b/Lib/test/libregrtest/runtest_mp.py
@@ -67,7 +67,7 @@
     try:
         result = runtest(ns, testname)
     except KeyboardInterrupt:
-        result = INTERRUPTED, ''
+        result = INTERRUPTED, '', None
     except BaseException as e:
         traceback.print_exc()
         result = CHILD_ERROR, str(e)
@@ -122,7 +122,7 @@
             self.current_test = None
 
         if retcode != 0:
-            result = (CHILD_ERROR, "Exit code %s" % retcode)
+            result = (CHILD_ERROR, "Exit code %s" % retcode, None)
             self.output.put((test, stdout.rstrip(), stderr.rstrip(),
                              result))
             return False
@@ -133,6 +133,7 @@
             return True
 
         result = json.loads(result)
+        assert len(result) == 3, f"Invalid result tuple: {result!r}"
         self.output.put((test, stdout.rstrip(), stderr.rstrip(),
                          result))
         return False
@@ -195,7 +196,7 @@
             regrtest.accumulate_result(test, result)
 
             # Display progress
-            ok, test_time = result
+            ok, test_time, xml_data = result
             text = format_test_result(test, ok)
             if (ok not in (CHILD_ERROR, INTERRUPTED)
                 and test_time >= PROGRESS_MIN_TIME
diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index de997b2..19701cf 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -6,6 +6,7 @@
 import asyncio.events
 import collections.abc
 import contextlib
+import datetime
 import errno
 import faulthandler
 import fnmatch
@@ -13,6 +14,7 @@
 import gc
 import importlib
 import importlib.util
+import io
 import logging.handlers
 import nntplib
 import os
@@ -34,6 +36,8 @@
 import urllib.error
 import warnings
 
+from .testresult import get_test_runner
+
 try:
     import multiprocessing.process
 except ImportError:
@@ -295,6 +299,7 @@
 max_memuse = 0           # Disable bigmem tests (they will still be run with
                          # small sizes, to make sure they work.)
 real_max_memuse = 0
+junit_xml_list = None    # list of testsuite XML elements
 failfast = False
 
 # _original_stdout is meant to hold stdout at the time regrtest began.
@@ -1891,13 +1896,16 @@
 
 def _run_suite(suite):
     """Run tests from a unittest.TestSuite-derived class."""
-    if verbose:
-        runner = unittest.TextTestRunner(sys.stdout, verbosity=2,
-                                         failfast=failfast)
-    else:
-        runner = BasicTestRunner()
+    runner = get_test_runner(sys.stdout, verbosity=verbose)
+
+    # TODO: Remove this before merging (here for easy comparison with old impl)
+    #runner = unittest.TextTestRunner(sys.stdout, verbosity=2, failfast=failfast)
 
     result = runner.run(suite)
+
+    if junit_xml_list is not None:
+        junit_xml_list.append(result.get_xml_element())
+
     if not result.wasSuccessful():
         if len(result.errors) == 1 and not result.failures:
             err = result.errors[0][1]
diff --git a/Lib/test/support/testresult.py b/Lib/test/support/testresult.py
new file mode 100644
index 0000000..8988d3d
--- /dev/null
+++ b/Lib/test/support/testresult.py
@@ -0,0 +1,201 @@
+'''Test runner and result class for the regression test suite.
+
+'''
+
+import functools
+import io
+import sys
+import time
+import traceback
+import unittest
+
+import xml.etree.ElementTree as ET
+
+from datetime import datetime
+
+class RegressionTestResult(unittest.TextTestResult):
+    separator1 = '=' * 70 + '\n'
+    separator2 = '-' * 70 + '\n'
+
+    def __init__(self, stream, descriptions, verbosity):
+        super().__init__(stream=stream, descriptions=descriptions, verbosity=0)
+        self.buffer = True
+        self.__suite = ET.Element('testsuite')
+        self.__suite.set('start', datetime.utcnow().isoformat(' '))
+
+        self.__e = None
+        self.__start_time = None
+        self.__results = []
+        self.__verbose = bool(verbosity)
+
+    @classmethod
+    def __getId(cls, test):
+        try:
+            test_id = test.id
+        except AttributeError:
+            return str(test)
+        try:
+            return test_id()
+        except TypeError:
+            return str(test_id)
+        return repr(test)
+
+    def startTest(self, test):
+        super().startTest(test)
+        self.__e = e = ET.SubElement(self.__suite, 'testcase')
+        self.__start_time = time.perf_counter()
+        if self.__verbose:
+            self.stream.write(f'{self.getDescription(test)} ... ')
+            self.stream.flush()
+
+    def _add_result(self, test, capture=False, **args):
+        e = self.__e
+        self.__e = None
+        if e is None:
+            return
+        e.set('name', args.pop('name', self.__getId(test)))
+        e.set('status', args.pop('status', 'run'))
+        e.set('result', args.pop('result', 'completed'))
+        if self.__start_time:
+            e.set('time', f'{time.perf_counter() - self.__start_time:0.6f}')
+
+        if capture:
+            stdout = self._stdout_buffer.getvalue().rstrip()
+            ET.SubElement(e, 'system-out').text = stdout
+            stderr = self._stderr_buffer.getvalue().rstrip()
+            ET.SubElement(e, 'system-err').text = stderr
+
+        for k, v in args.items():
+            if not k or not v:
+                continue
+            e2 = ET.SubElement(e, k)
+            if hasattr(v, 'items'):
+                for k2, v2 in v.items():
+                    if k2:
+                        e2.set(k2, str(v2))
+                    else:
+                        e2.text = str(v2)
+            else:
+                e2.text = str(v)
+
+    def __write(self, c, word):
+        if self.__verbose:
+            self.stream.write(f'{word}\n')
+
+    @classmethod
+    def __makeErrorDict(cls, err_type, err_value, err_tb):
+        if isinstance(err_type, type):
+            if err_type.__module__ == 'builtins':
+                typename = err_type.__name__
+            else:
+                typename = f'{err_type.__module__}.{err_type.__name__}'
+        else:
+            typename = repr(err_type)
+
+        msg = traceback.format_exception(err_type, err_value, None)
+        tb = traceback.format_exception(err_type, err_value, err_tb)
+
+        return {
+            'type': typename,
+            'message': ''.join(msg),
+            '': ''.join(tb),
+        }
+
+    def addError(self, test, err):
+        self._add_result(test, True, error=self.__makeErrorDict(*err))
+        super().addError(test, err)
+        self.__write('E', 'ERROR')
+
+    def addExpectedFailure(self, test, err):
+        self._add_result(test, True, output=self.__makeErrorDict(*err))
+        super().addExpectedFailure(test, err)
+        self.__write('x', 'expected failure')
+
+    def addFailure(self, test, err):
+        self._add_result(test, True, failure=self.__makeErrorDict(*err))
+        super().addFailure(test, err)
+        self.__write('F', 'FAIL')
+
+    def addSkip(self, test, reason):
+        self._add_result(test, skipped=reason)
+        super().addSkip(test, reason)
+        self.__write('S', f'skipped {reason!r}')
+
+    def addSuccess(self, test):
+        self._add_result(test)
+        super().addSuccess(test)
+        self.__write('.', 'ok')
+
+    def addUnexpectedSuccess(self, test):
+        self._add_result(test, outcome='UNEXPECTED_SUCCESS')
+        super().addUnexpectedSuccess(test)
+        self.__write('u', 'unexpected success')
+
+    def printErrors(self):
+        if self.__verbose:
+            self.stream.write('\n')
+        self.printErrorList('ERROR', self.errors)
+        self.printErrorList('FAIL', self.failures)
+
+    def printErrorList(self, flavor, errors):
+        for test, err in errors:
+            self.stream.write(self.separator1)
+            self.stream.write(f'{flavor}: {self.getDescription(test)}\n')
+            self.stream.write(self.separator2)
+            self.stream.write('%s\n' % err)
+
+    def get_xml_element(self):
+        e = self.__suite
+        e.set('tests', str(self.testsRun))
+        e.set('errors', str(len(self.errors)))
+        e.set('failures', str(len(self.failures)))
+        return e
+
+class QuietRegressionTestRunner:
+    def __init__(self, stream):
+        self.result = RegressionTestResult(stream, None, 0)
+
+    def run(self, test):
+        test(self.result)
+        return self.result
+
+def get_test_runner_class(verbosity):
+    if verbosity:
+        return functools.partial(unittest.TextTestRunner,
+                                 resultclass=RegressionTestResult,
+                                 buffer=True,
+                                 verbosity=verbosity)
+    return QuietRegressionTestRunner
+
+def get_test_runner(stream, verbosity):
+    return get_test_runner_class(verbosity)(stream)
+
+if __name__ == '__main__':
+    class TestTests(unittest.TestCase):
+        def test_pass(self):
+            pass
+
+        def test_pass_slow(self):
+            time.sleep(1.0)
+
+        def test_fail(self):
+            print('stdout', file=sys.stdout)
+            print('stderr', file=sys.stderr)
+            self.fail('failure message')
+
+        def test_error(self):
+            print('stdout', file=sys.stdout)
+            print('stderr', file=sys.stderr)
+            raise RuntimeError('error message')
+
+    suite = unittest.TestSuite()
+    suite.addTest(unittest.makeSuite(TestTests))
+    stream = io.StringIO()
+    runner_cls = get_test_runner_class(sum(a == '-v' for a in sys.argv))
+    runner = runner_cls(sys.stdout)
+    result = runner.run(suite)
+    print('Output:', stream.getvalue())
+    print('XML: ', end='')
+    for s in ET.tostringlist(result.get_xml_element()):
+        print(s.decode(), end='')
+    print()
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index f0802a5..c0c7cb0 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -1459,6 +1459,16 @@
         type = argparse.FileType('r', 1, errors='replace')
         self.assertEqual("FileType('r', 1, errors='replace')", repr(type))
 
+class StdStreamComparer:
+    def __init__(self, attr):
+        self.attr = attr
+
+    def __eq__(self, other):
+        return other == getattr(sys, self.attr)
+
+eq_stdin = StdStreamComparer('stdin')
+eq_stdout = StdStreamComparer('stdout')
+eq_stderr = StdStreamComparer('stderr')
 
 class RFile(object):
     seen = {}
@@ -1497,7 +1507,7 @@
         ('foo', NS(x=None, spam=RFile('foo'))),
         ('-x foo bar', NS(x=RFile('foo'), spam=RFile('bar'))),
         ('bar -x foo', NS(x=RFile('foo'), spam=RFile('bar'))),
-        ('-x - -', NS(x=sys.stdin, spam=sys.stdin)),
+        ('-x - -', NS(x=eq_stdin, spam=eq_stdin)),
         ('readonly', NS(x=None, spam=RFile('readonly'))),
     ]
 
@@ -1537,7 +1547,7 @@
         ('foo', NS(x=None, spam=RFile('foo'))),
         ('-x foo bar', NS(x=RFile('foo'), spam=RFile('bar'))),
         ('bar -x foo', NS(x=RFile('foo'), spam=RFile('bar'))),
-        ('-x - -', NS(x=sys.stdin, spam=sys.stdin)),
+        ('-x - -', NS(x=eq_stdin, spam=eq_stdin)),
     ]
 
 
@@ -1576,7 +1586,7 @@
         ('foo', NS(x=None, spam=WFile('foo'))),
         ('-x foo bar', NS(x=WFile('foo'), spam=WFile('bar'))),
         ('bar -x foo', NS(x=WFile('foo'), spam=WFile('bar'))),
-        ('-x - -', NS(x=sys.stdout, spam=sys.stdout)),
+        ('-x - -', NS(x=eq_stdout, spam=eq_stdout)),
     ]
 
 
@@ -1591,7 +1601,7 @@
         ('foo', NS(x=None, spam=WFile('foo'))),
         ('-x foo bar', NS(x=WFile('foo'), spam=WFile('bar'))),
         ('bar -x foo', NS(x=WFile('foo'), spam=WFile('bar'))),
-        ('-x - -', NS(x=sys.stdout, spam=sys.stdout)),
+        ('-x - -', NS(x=eq_stdout, spam=eq_stdout)),
     ]
 
 
diff --git a/Misc/NEWS.d/next/Build/2018-09-14-09-53-21.bpo-34582.j3omgk.rst b/Misc/NEWS.d/next/Build/2018-09-14-09-53-21.bpo-34582.j3omgk.rst
new file mode 100644
index 0000000..582c15f
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2018-09-14-09-53-21.bpo-34582.j3omgk.rst
@@ -0,0 +1 @@
+Add JUnit XML output for regression tests and update Azure DevOps builds.