diff --git a/Lib/test/libregrtest/__init__.py b/Lib/test/libregrtest/__init__.py
deleted file mode 100644
index 554aeed..0000000
--- a/Lib/test/libregrtest/__init__.py
+++ /dev/null
@@ -1 +0,0 @@
-from test.libregrtest.cmdline import _parse_args, RESOURCE_NAMES
diff --git a/Lib/test/libregrtest/cmdline.py b/Lib/test/libregrtest/cmdline.py
deleted file mode 100644
index 9464996..0000000
--- a/Lib/test/libregrtest/cmdline.py
+++ /dev/null
@@ -1,340 +0,0 @@
-import argparse
-import faulthandler
-import os
-
-from test import support
-
-USAGE = """\
-python -m test [options] [test_name1 [test_name2 ...]]
-python path/to/Lib/test/regrtest.py [options] [test_name1 [test_name2 ...]]
-"""
-
-DESCRIPTION = """\
-Run Python regression tests.
-
-If no arguments or options are provided, finds all files matching
-the pattern "test_*" in the Lib/test subdirectory and runs
-them in alphabetical order (but see -M and -u, below, for exceptions).
-
-For more rigorous testing, it is useful to use the following
-command line:
-
-python -E -Wd -m test [options] [test_name1 ...]
-"""
-
-EPILOG = """\
-Additional option details:
-
--r randomizes test execution order. You can use --randseed=int to provide a
-int seed value for the randomizer; this is useful for reproducing troublesome
-test orders.
-
--s On the first invocation of regrtest using -s, the first test file found
-or the first test file given on the command line is run, and the name of
-the next test is recorded in a file named pynexttest.  If run from the
-Python build directory, pynexttest is located in the 'build' subdirectory,
-otherwise it is located in tempfile.gettempdir().  On subsequent runs,
-the test in pynexttest is run, and the next test is written to pynexttest.
-When the last test has been run, pynexttest is deleted.  In this way it
-is possible to single step through the test files.  This is useful when
-doing memory analysis on the Python interpreter, which process tends to
-consume too many resources to run the full regression test non-stop.
-
--S is used to continue running tests after an aborted run.  It will
-maintain the order a standard run (ie, this assumes -r is not used).
-This is useful after the tests have prematurely stopped for some external
-reason and you want to start running from where you left off rather
-than starting from the beginning.
-
--f reads the names of tests from the file given as f's argument, one
-or more test names per line.  Whitespace is ignored.  Blank lines and
-lines beginning with '#' are ignored.  This is especially useful for
-whittling down failures involving interactions among tests.
-
--L causes the leaks(1) command to be run just before exit if it exists.
-leaks(1) is available on Mac OS X and presumably on some other
-FreeBSD-derived systems.
-
--R runs each test several times and examines sys.gettotalrefcount() to
-see if the test appears to be leaking references.  The argument should
-be of the form stab:run:fname where 'stab' is the number of times the
-test is run to let gettotalrefcount settle down, 'run' is the number
-of times further it is run and 'fname' is the name of the file the
-reports are written to.  These parameters all have defaults (5, 4 and
-"reflog.txt" respectively), and the minimal invocation is '-R :'.
-
--M runs tests that require an exorbitant amount of memory. These tests
-typically try to ascertain containers keep working when containing more than
-2 billion objects, which only works on 64-bit systems. There are also some
-tests that try to exhaust the address space of the process, which only makes
-sense on 32-bit systems with at least 2Gb of memory. The passed-in memlimit,
-which is a string in the form of '2.5Gb', determines howmuch memory the
-tests will limit themselves to (but they may go slightly over.) The number
-shouldn't be more memory than the machine has (including swap memory). You
-should also keep in mind that swap memory is generally much, much slower
-than RAM, and setting memlimit to all available RAM or higher will heavily
-tax the machine. On the other hand, it is no use running these tests with a
-limit of less than 2.5Gb, and many require more than 20Gb. Tests that expect
-to use more than memlimit memory will be skipped. The big-memory tests
-generally run very, very long.
-
--u is used to specify which special resource intensive tests to run,
-such as those requiring large file support or network connectivity.
-The argument is a comma-separated list of words indicating the
-resources to test.  Currently only the following are defined:
-
-    all -       Enable all special resources.
-
-    none -      Disable all special resources (this is the default).
-
-    audio -     Tests that use the audio device.  (There are known
-                cases of broken audio drivers that can crash Python or
-                even the Linux kernel.)
-
-    curses -    Tests that use curses and will modify the terminal's
-                state and output modes.
-
-    largefile - It is okay to run some test that may create huge
-                files.  These tests can take a long time and may
-                consume >2GB of disk space temporarily.
-
-    network -   It is okay to run tests that use external network
-                resource, e.g. testing SSL support for sockets.
-
-    decimal -   Test the decimal module against a large suite that
-                verifies compliance with standards.
-
-    cpu -       Used for certain CPU-heavy tests.
-
-    subprocess  Run all tests for the subprocess module.
-
-    urlfetch -  It is okay to download files required on testing.
-
-    gui -       Run tests that require a running GUI.
-
-To enable all resources except one, use '-uall,-<resource>'.  For
-example, to run all the tests except for the gui tests, give the
-option '-uall,-gui'.
-"""
-
-
-RESOURCE_NAMES = ('audio', 'curses', 'largefile', 'network',
-                  'decimal', 'cpu', 'subprocess', 'urlfetch', 'gui')
-
-class _ArgParser(argparse.ArgumentParser):
-
-    def error(self, message):
-        super().error(message + "\nPass -h or --help for complete help.")
-
-
-def _create_parser():
-    # Set prog to prevent the uninformative "__main__.py" from displaying in
-    # error messages when using "python -m test ...".
-    parser = _ArgParser(prog='regrtest.py',
-                        usage=USAGE,
-                        description=DESCRIPTION,
-                        epilog=EPILOG,
-                        add_help=False,
-                        formatter_class=argparse.RawDescriptionHelpFormatter)
-
-    # Arguments with this clause added to its help are described further in
-    # the epilog's "Additional option details" section.
-    more_details = '  See the section at bottom for more details.'
-
-    group = parser.add_argument_group('General options')
-    # We add help explicitly to control what argument group it renders under.
-    group.add_argument('-h', '--help', action='help',
-                       help='show this help message and exit')
-    group.add_argument('--timeout', metavar='TIMEOUT', type=float,
-                        help='dump the traceback and exit if a test takes '
-                             'more than TIMEOUT seconds; disabled if TIMEOUT '
-                             'is negative or equals to zero')
-    group.add_argument('--wait', action='store_true',
-                       help='wait for user input, e.g., allow a debugger '
-                            'to be attached')
-    group.add_argument('--slaveargs', metavar='ARGS')
-    group.add_argument('-S', '--start', metavar='START',
-                       help='the name of the test at which to start.' +
-                            more_details)
-
-    group = parser.add_argument_group('Verbosity')
-    group.add_argument('-v', '--verbose', action='count',
-                       help='run tests in verbose mode with output to stdout')
-    group.add_argument('-w', '--verbose2', action='store_true',
-                       help='re-run failed tests in verbose mode')
-    group.add_argument('-W', '--verbose3', action='store_true',
-                       help='display test output on failure')
-    group.add_argument('-q', '--quiet', action='store_true',
-                       help='no output unless one or more tests fail')
-    group.add_argument('-o', '--slow', action='store_true', dest='print_slow',
-                       help='print the slowest 10 tests')
-    group.add_argument('--header', action='store_true',
-                       help='print header with interpreter info')
-
-    group = parser.add_argument_group('Selecting tests')
-    group.add_argument('-r', '--randomize', action='store_true',
-                       help='randomize test execution order.' + more_details)
-    group.add_argument('--randseed', metavar='SEED',
-                       dest='random_seed', type=int,
-                       help='pass a random seed to reproduce a previous '
-                            'random run')
-    group.add_argument('-f', '--fromfile', metavar='FILE',
-                       help='read names of tests to run from a file.' +
-                            more_details)
-    group.add_argument('-x', '--exclude', action='store_true',
-                       help='arguments are tests to *exclude*')
-    group.add_argument('-s', '--single', action='store_true',
-                       help='single step through a set of tests.' +
-                            more_details)
-    group.add_argument('-m', '--match', metavar='PAT',
-                       dest='match_tests',
-                       help='match test cases and methods with glob pattern PAT')
-    group.add_argument('-G', '--failfast', action='store_true',
-                       help='fail as soon as a test fails (only with -v or -W)')
-    group.add_argument('-u', '--use', metavar='RES1,RES2,...',
-                       action='append', type=resources_list,
-                       help='specify which special resource intensive tests '
-                            'to run.' + more_details)
-    group.add_argument('-M', '--memlimit', metavar='LIMIT',
-                       help='run very large memory-consuming tests.' +
-                            more_details)
-    group.add_argument('--testdir', metavar='DIR',
-                       type=relative_filename,
-                       help='execute test files in the specified directory '
-                            '(instead of the Python stdlib test suite)')
-
-    group = parser.add_argument_group('Special runs')
-    group.add_argument('-l', '--findleaks', action='store_true',
-                       help='if GC is available detect tests that leak memory')
-    group.add_argument('-L', '--runleaks', action='store_true',
-                       help='run the leaks(1) command just before exit.' +
-                            more_details)
-    group.add_argument('-R', '--huntrleaks', metavar='RUNCOUNTS',
-                       type=huntrleaks,
-                       help='search for reference leaks (needs debug build, '
-                            'very slow).' + more_details)
-    group.add_argument('-j', '--multiprocess', metavar='PROCESSES',
-                       dest='use_mp', type=int,
-                       help='run PROCESSES processes at once')
-    group.add_argument('-T', '--coverage', action='store_true',
-                       dest='trace',
-                       help='turn on code coverage tracing using the trace '
-                            'module')
-    group.add_argument('-D', '--coverdir', metavar='DIR',
-                       type=relative_filename,
-                       help='directory where coverage files are put')
-    group.add_argument('-N', '--nocoverdir',
-                       action='store_const', const=None, dest='coverdir',
-                       help='put coverage files alongside modules')
-    group.add_argument('-t', '--threshold', metavar='THRESHOLD',
-                       type=int,
-                       help='call gc.set_threshold(THRESHOLD)')
-    group.add_argument('-n', '--nowindows', action='store_true',
-                       help='suppress error message boxes on Windows')
-    group.add_argument('-F', '--forever', action='store_true',
-                       help='run the specified tests in a loop, until an '
-                            'error happens')
-
-    parser.add_argument('args', nargs=argparse.REMAINDER,
-                        help=argparse.SUPPRESS)
-
-    return parser
-
-
-def relative_filename(string):
-    # CWD is replaced with a temporary dir before calling main(), so we
-    # join it with the saved CWD so it ends up where the user expects.
-    return os.path.join(support.SAVEDCWD, string)
-
-
-def huntrleaks(string):
-    args = string.split(':')
-    if len(args) not in (2, 3):
-        raise argparse.ArgumentTypeError(
-            'needs 2 or 3 colon-separated arguments')
-    nwarmup = int(args[0]) if args[0] else 5
-    ntracked = int(args[1]) if args[1] else 4
-    fname = args[2] if len(args) > 2 and args[2] else 'reflog.txt'
-    return nwarmup, ntracked, fname
-
-
-def resources_list(string):
-    u = [x.lower() for x in string.split(',')]
-    for r in u:
-        if r == 'all' or r == 'none':
-            continue
-        if r[0] == '-':
-            r = r[1:]
-        if r not in RESOURCE_NAMES:
-            raise argparse.ArgumentTypeError('invalid resource: ' + r)
-    return u
-
-
-def _parse_args(args, **kwargs):
-    # Defaults
-    ns = argparse.Namespace(testdir=None, verbose=0, quiet=False,
-         exclude=False, single=False, randomize=False, fromfile=None,
-         findleaks=False, use_resources=None, trace=False, coverdir='coverage',
-         runleaks=False, huntrleaks=False, verbose2=False, print_slow=False,
-         random_seed=None, use_mp=None, verbose3=False, forever=False,
-         header=False, failfast=False, match_tests=None)
-    for k, v in kwargs.items():
-        if not hasattr(ns, k):
-            raise TypeError('%r is an invalid keyword argument '
-                            'for this function' % k)
-        setattr(ns, k, v)
-    if ns.use_resources is None:
-        ns.use_resources = []
-
-    parser = _create_parser()
-    parser.parse_args(args=args, namespace=ns)
-
-    if ns.single and ns.fromfile:
-        parser.error("-s and -f don't go together!")
-    if ns.use_mp and ns.trace:
-        parser.error("-T and -j don't go together!")
-    if ns.use_mp and ns.findleaks:
-        parser.error("-l and -j don't go together!")
-    if ns.use_mp and ns.memlimit:
-        parser.error("-M and -j don't go together!")
-    if ns.failfast and not (ns.verbose or ns.verbose3):
-        parser.error("-G/--failfast needs either -v or -W")
-
-    if ns.quiet:
-        ns.verbose = 0
-    if ns.timeout is not None:
-        if hasattr(faulthandler, 'dump_traceback_later'):
-            if ns.timeout <= 0:
-                ns.timeout = None
-        else:
-            print("Warning: The timeout option requires "
-                  "faulthandler.dump_traceback_later")
-            ns.timeout = None
-    if ns.use_mp is not None:
-        if ns.use_mp <= 0:
-            # Use all cores + extras for tests that like to sleep
-            ns.use_mp = 2 + (os.cpu_count() or 1)
-        if ns.use_mp == 1:
-            ns.use_mp = None
-    if ns.use:
-        for a in ns.use:
-            for r in a:
-                if r == 'all':
-                    ns.use_resources[:] = RESOURCE_NAMES
-                    continue
-                if r == 'none':
-                    del ns.use_resources[:]
-                    continue
-                remove = False
-                if r[0] == '-':
-                    remove = True
-                    r = r[1:]
-                if remove:
-                    if r in ns.use_resources:
-                        ns.use_resources.remove(r)
-                elif r not in ns.use_resources:
-                    ns.use_resources.append(r)
-    if ns.random_seed is not None:
-        ns.randomize = True
-
-    return ns
diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index 51e9e18..b49e66b 100755
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -6,6 +6,119 @@
 Run this script with -h or --help for documentation.
 """
 
+USAGE = """\
+python -m test [options] [test_name1 [test_name2 ...]]
+python path/to/Lib/test/regrtest.py [options] [test_name1 [test_name2 ...]]
+"""
+
+DESCRIPTION = """\
+Run Python regression tests.
+
+If no arguments or options are provided, finds all files matching
+the pattern "test_*" in the Lib/test subdirectory and runs
+them in alphabetical order (but see -M and -u, below, for exceptions).
+
+For more rigorous testing, it is useful to use the following
+command line:
+
+python -E -Wd -m test [options] [test_name1 ...]
+"""
+
+EPILOG = """\
+Additional option details:
+
+-r randomizes test execution order. You can use --randseed=int to provide a
+int seed value for the randomizer; this is useful for reproducing troublesome
+test orders.
+
+-s On the first invocation of regrtest using -s, the first test file found
+or the first test file given on the command line is run, and the name of
+the next test is recorded in a file named pynexttest.  If run from the
+Python build directory, pynexttest is located in the 'build' subdirectory,
+otherwise it is located in tempfile.gettempdir().  On subsequent runs,
+the test in pynexttest is run, and the next test is written to pynexttest.
+When the last test has been run, pynexttest is deleted.  In this way it
+is possible to single step through the test files.  This is useful when
+doing memory analysis on the Python interpreter, which process tends to
+consume too many resources to run the full regression test non-stop.
+
+-S is used to continue running tests after an aborted run.  It will
+maintain the order a standard run (ie, this assumes -r is not used).
+This is useful after the tests have prematurely stopped for some external
+reason and you want to start running from where you left off rather
+than starting from the beginning.
+
+-f reads the names of tests from the file given as f's argument, one
+or more test names per line.  Whitespace is ignored.  Blank lines and
+lines beginning with '#' are ignored.  This is especially useful for
+whittling down failures involving interactions among tests.
+
+-L causes the leaks(1) command to be run just before exit if it exists.
+leaks(1) is available on Mac OS X and presumably on some other
+FreeBSD-derived systems.
+
+-R runs each test several times and examines sys.gettotalrefcount() to
+see if the test appears to be leaking references.  The argument should
+be of the form stab:run:fname where 'stab' is the number of times the
+test is run to let gettotalrefcount settle down, 'run' is the number
+of times further it is run and 'fname' is the name of the file the
+reports are written to.  These parameters all have defaults (5, 4 and
+"reflog.txt" respectively), and the minimal invocation is '-R :'.
+
+-M runs tests that require an exorbitant amount of memory. These tests
+typically try to ascertain containers keep working when containing more than
+2 billion objects, which only works on 64-bit systems. There are also some
+tests that try to exhaust the address space of the process, which only makes
+sense on 32-bit systems with at least 2Gb of memory. The passed-in memlimit,
+which is a string in the form of '2.5Gb', determines howmuch memory the
+tests will limit themselves to (but they may go slightly over.) The number
+shouldn't be more memory than the machine has (including swap memory). You
+should also keep in mind that swap memory is generally much, much slower
+than RAM, and setting memlimit to all available RAM or higher will heavily
+tax the machine. On the other hand, it is no use running these tests with a
+limit of less than 2.5Gb, and many require more than 20Gb. Tests that expect
+to use more than memlimit memory will be skipped. The big-memory tests
+generally run very, very long.
+
+-u is used to specify which special resource intensive tests to run,
+such as those requiring large file support or network connectivity.
+The argument is a comma-separated list of words indicating the
+resources to test.  Currently only the following are defined:
+
+    all -       Enable all special resources.
+
+    none -      Disable all special resources (this is the default).
+
+    audio -     Tests that use the audio device.  (There are known
+                cases of broken audio drivers that can crash Python or
+                even the Linux kernel.)
+
+    curses -    Tests that use curses and will modify the terminal's
+                state and output modes.
+
+    largefile - It is okay to run some test that may create huge
+                files.  These tests can take a long time and may
+                consume >2GB of disk space temporarily.
+
+    network -   It is okay to run tests that use external network
+                resource, e.g. testing SSL support for sockets.
+
+    decimal -   Test the decimal module against a large suite that
+                verifies compliance with standards.
+
+    cpu -       Used for certain CPU-heavy tests.
+
+    subprocess  Run all tests for the subprocess module.
+
+    urlfetch -  It is okay to download files required on testing.
+
+    gui -       Run tests that require a running GUI.
+
+To enable all resources except one, use '-uall,-<resource>'.  For
+example, to run all the tests except for the gui tests, give the
+option '-uall,-gui'.
+"""
+
 # We import importlib *ASAP* in order to test #15386
 import importlib
 
@@ -40,8 +153,6 @@
 except ImportError:
     multiprocessing = None
 
-from test.libregrtest import _parse_args
-
 
 # Some times __path__ and __file__ are not absolute (e.g. while running from
 # Lib/) and, if we change the CWD to run the tests in a temporary dir, some
@@ -87,6 +198,9 @@
 
 from test import support
 
+RESOURCE_NAMES = ('audio', 'curses', 'largefile', 'network',
+                  'decimal', 'cpu', 'subprocess', 'urlfetch', 'gui')
+
 # When tests are run from the Python build directory, it is best practice
 # to keep the test files in a subfolder.  This eases the cleanup of leftover
 # files using the "make distclean" command.
@@ -96,6 +210,220 @@
     TEMPDIR = tempfile.gettempdir()
 TEMPDIR = os.path.abspath(TEMPDIR)
 
+class _ArgParser(argparse.ArgumentParser):
+
+    def error(self, message):
+        super().error(message + "\nPass -h or --help for complete help.")
+
+def _create_parser():
+    # Set prog to prevent the uninformative "__main__.py" from displaying in
+    # error messages when using "python -m test ...".
+    parser = _ArgParser(prog='regrtest.py',
+                        usage=USAGE,
+                        description=DESCRIPTION,
+                        epilog=EPILOG,
+                        add_help=False,
+                        formatter_class=argparse.RawDescriptionHelpFormatter)
+
+    # Arguments with this clause added to its help are described further in
+    # the epilog's "Additional option details" section.
+    more_details = '  See the section at bottom for more details.'
+
+    group = parser.add_argument_group('General options')
+    # We add help explicitly to control what argument group it renders under.
+    group.add_argument('-h', '--help', action='help',
+                       help='show this help message and exit')
+    group.add_argument('--timeout', metavar='TIMEOUT', type=float,
+                        help='dump the traceback and exit if a test takes '
+                             'more than TIMEOUT seconds; disabled if TIMEOUT '
+                             'is negative or equals to zero')
+    group.add_argument('--wait', action='store_true',
+                       help='wait for user input, e.g., allow a debugger '
+                            'to be attached')
+    group.add_argument('--slaveargs', metavar='ARGS')
+    group.add_argument('-S', '--start', metavar='START',
+                       help='the name of the test at which to start.' +
+                            more_details)
+
+    group = parser.add_argument_group('Verbosity')
+    group.add_argument('-v', '--verbose', action='count',
+                       help='run tests in verbose mode with output to stdout')
+    group.add_argument('-w', '--verbose2', action='store_true',
+                       help='re-run failed tests in verbose mode')
+    group.add_argument('-W', '--verbose3', action='store_true',
+                       help='display test output on failure')
+    group.add_argument('-q', '--quiet', action='store_true',
+                       help='no output unless one or more tests fail')
+    group.add_argument('-o', '--slow', action='store_true', dest='print_slow',
+                       help='print the slowest 10 tests')
+    group.add_argument('--header', action='store_true',
+                       help='print header with interpreter info')
+
+    group = parser.add_argument_group('Selecting tests')
+    group.add_argument('-r', '--randomize', action='store_true',
+                       help='randomize test execution order.' + more_details)
+    group.add_argument('--randseed', metavar='SEED',
+                       dest='random_seed', type=int,
+                       help='pass a random seed to reproduce a previous '
+                            'random run')
+    group.add_argument('-f', '--fromfile', metavar='FILE',
+                       help='read names of tests to run from a file.' +
+                            more_details)
+    group.add_argument('-x', '--exclude', action='store_true',
+                       help='arguments are tests to *exclude*')
+    group.add_argument('-s', '--single', action='store_true',
+                       help='single step through a set of tests.' +
+                            more_details)
+    group.add_argument('-m', '--match', metavar='PAT',
+                       dest='match_tests',
+                       help='match test cases and methods with glob pattern PAT')
+    group.add_argument('-G', '--failfast', action='store_true',
+                       help='fail as soon as a test fails (only with -v or -W)')
+    group.add_argument('-u', '--use', metavar='RES1,RES2,...',
+                       action='append', type=resources_list,
+                       help='specify which special resource intensive tests '
+                            'to run.' + more_details)
+    group.add_argument('-M', '--memlimit', metavar='LIMIT',
+                       help='run very large memory-consuming tests.' +
+                            more_details)
+    group.add_argument('--testdir', metavar='DIR',
+                       type=relative_filename,
+                       help='execute test files in the specified directory '
+                            '(instead of the Python stdlib test suite)')
+
+    group = parser.add_argument_group('Special runs')
+    group.add_argument('-l', '--findleaks', action='store_true',
+                       help='if GC is available detect tests that leak memory')
+    group.add_argument('-L', '--runleaks', action='store_true',
+                       help='run the leaks(1) command just before exit.' +
+                            more_details)
+    group.add_argument('-R', '--huntrleaks', metavar='RUNCOUNTS',
+                       type=huntrleaks,
+                       help='search for reference leaks (needs debug build, '
+                            'very slow).' + more_details)
+    group.add_argument('-j', '--multiprocess', metavar='PROCESSES',
+                       dest='use_mp', type=int,
+                       help='run PROCESSES processes at once')
+    group.add_argument('-T', '--coverage', action='store_true',
+                       dest='trace',
+                       help='turn on code coverage tracing using the trace '
+                            'module')
+    group.add_argument('-D', '--coverdir', metavar='DIR',
+                       type=relative_filename,
+                       help='directory where coverage files are put')
+    group.add_argument('-N', '--nocoverdir',
+                       action='store_const', const=None, dest='coverdir',
+                       help='put coverage files alongside modules')
+    group.add_argument('-t', '--threshold', metavar='THRESHOLD',
+                       type=int,
+                       help='call gc.set_threshold(THRESHOLD)')
+    group.add_argument('-n', '--nowindows', action='store_true',
+                       help='suppress error message boxes on Windows')
+    group.add_argument('-F', '--forever', action='store_true',
+                       help='run the specified tests in a loop, until an '
+                            'error happens')
+
+    parser.add_argument('args', nargs=argparse.REMAINDER,
+                        help=argparse.SUPPRESS)
+
+    return parser
+
+def relative_filename(string):
+    # CWD is replaced with a temporary dir before calling main(), so we
+    # join it with the saved CWD so it ends up where the user expects.
+    return os.path.join(support.SAVEDCWD, string)
+
+def huntrleaks(string):
+    args = string.split(':')
+    if len(args) not in (2, 3):
+        raise argparse.ArgumentTypeError(
+            'needs 2 or 3 colon-separated arguments')
+    nwarmup = int(args[0]) if args[0] else 5
+    ntracked = int(args[1]) if args[1] else 4
+    fname = args[2] if len(args) > 2 and args[2] else 'reflog.txt'
+    return nwarmup, ntracked, fname
+
+def resources_list(string):
+    u = [x.lower() for x in string.split(',')]
+    for r in u:
+        if r == 'all' or r == 'none':
+            continue
+        if r[0] == '-':
+            r = r[1:]
+        if r not in RESOURCE_NAMES:
+            raise argparse.ArgumentTypeError('invalid resource: ' + r)
+    return u
+
+def _parse_args(args, **kwargs):
+    # Defaults
+    ns = argparse.Namespace(testdir=None, verbose=0, quiet=False,
+         exclude=False, single=False, randomize=False, fromfile=None,
+         findleaks=False, use_resources=None, trace=False, coverdir='coverage',
+         runleaks=False, huntrleaks=False, verbose2=False, print_slow=False,
+         random_seed=None, use_mp=None, verbose3=False, forever=False,
+         header=False, failfast=False, match_tests=None)
+    for k, v in kwargs.items():
+        if not hasattr(ns, k):
+            raise TypeError('%r is an invalid keyword argument '
+                            'for this function' % k)
+        setattr(ns, k, v)
+    if ns.use_resources is None:
+        ns.use_resources = []
+
+    parser = _create_parser()
+    parser.parse_args(args=args, namespace=ns)
+
+    if ns.single and ns.fromfile:
+        parser.error("-s and -f don't go together!")
+    if ns.use_mp and ns.trace:
+        parser.error("-T and -j don't go together!")
+    if ns.use_mp and ns.findleaks:
+        parser.error("-l and -j don't go together!")
+    if ns.use_mp and ns.memlimit:
+        parser.error("-M and -j don't go together!")
+    if ns.failfast and not (ns.verbose or ns.verbose3):
+        parser.error("-G/--failfast needs either -v or -W")
+
+    if ns.quiet:
+        ns.verbose = 0
+    if ns.timeout is not None:
+        if hasattr(faulthandler, 'dump_traceback_later'):
+            if ns.timeout <= 0:
+                ns.timeout = None
+        else:
+            print("Warning: The timeout option requires "
+                  "faulthandler.dump_traceback_later")
+            ns.timeout = None
+    if ns.use_mp is not None:
+        if ns.use_mp <= 0:
+            # Use all cores + extras for tests that like to sleep
+            ns.use_mp = 2 + (os.cpu_count() or 1)
+        if ns.use_mp == 1:
+            ns.use_mp = None
+    if ns.use:
+        for a in ns.use:
+            for r in a:
+                if r == 'all':
+                    ns.use_resources[:] = RESOURCE_NAMES
+                    continue
+                if r == 'none':
+                    del ns.use_resources[:]
+                    continue
+                remove = False
+                if r[0] == '-':
+                    remove = True
+                    r = r[1:]
+                if remove:
+                    if r in ns.use_resources:
+                        ns.use_resources.remove(r)
+                elif r not in ns.use_resources:
+                    ns.use_resources.append(r)
+    if ns.random_seed is not None:
+        ns.randomize = True
+
+    return ns
+
+
 def run_test_in_subprocess(testname, ns):
     """Run the given test in a subprocess with --slaveargs.
 
diff --git a/Lib/test/test_regrtest.py b/Lib/test/test_regrtest.py
index cf4b84f..a398a4f 100644
--- a/Lib/test/test_regrtest.py
+++ b/Lib/test/test_regrtest.py
@@ -7,7 +7,7 @@
 import getopt
 import os.path
 import unittest
-from test import regrtest, support, libregrtest
+from test import regrtest, support
 
 class ParseArgsTestCase(unittest.TestCase):
 
@@ -148,7 +148,7 @@
                 self.assertEqual(ns.use_resources, ['gui', 'network'])
                 ns = regrtest._parse_args([opt, 'gui,none,network'])
                 self.assertEqual(ns.use_resources, ['network'])
-                expected = list(libregrtest.RESOURCE_NAMES)
+                expected = list(regrtest.RESOURCE_NAMES)
                 expected.remove('gui')
                 ns = regrtest._parse_args([opt, 'all,-gui'])
                 self.assertEqual(ns.use_resources, expected)