diff --git a/Lib/_strptime.py b/Lib/_strptime.py
new file mode 100644
index 0000000..f4f3c0b
--- /dev/null
+++ b/Lib/_strptime.py
@@ -0,0 +1,579 @@
+"""Strptime-related classes and functions.
+
+CLASSES:
+    LocaleTime -- Discovers and stores locale-specific time information
+    TimeRE -- Creates regexes for pattern matching a string of text containing
+                time information
+
+FUNCTIONS:
+    _getlang -- Figure out what language is being used for the locale
+    strptime -- Calculates the time struct represented by the passed-in string
+
+"""
+import time
+import locale
+import calendar
+from re import compile as re_compile
+from re import IGNORECASE
+from re import escape as re_escape
+from datetime import (date as datetime_date,
+                      timedelta as datetime_timedelta,
+                      timezone as datetime_timezone)
+from _thread import allocate_lock as _thread_allocate_lock
+
+__all__ = []
+
+def _getlang():
+    # Figure out what the current language is set to.
+    return locale.getlocale(locale.LC_TIME)
+
+class LocaleTime(object):
+    """Stores and handles locale-specific information related to time.
+
+    ATTRIBUTES:
+        f_weekday -- full weekday names (7-item list)
+        a_weekday -- abbreviated weekday names (7-item list)
+        f_month -- full month names (13-item list; dummy value in [0], which
+                    is added by code)
+        a_month -- abbreviated month names (13-item list, dummy value in
+                    [0], which is added by code)
+        am_pm -- AM/PM representation (2-item list)
+        LC_date_time -- format string for date/time representation (string)
+        LC_date -- format string for date representation (string)
+        LC_time -- format string for time representation (string)
+        timezone -- daylight- and non-daylight-savings timezone representation
+                    (2-item list of sets)
+        lang -- Language used by instance (2-item tuple)
+    """
+
+    def __init__(self):
+        """Set all attributes.
+
+        Order of methods called matters for dependency reasons.
+
+        The locale language is set at the offset and then checked again before
+        exiting.  This is to make sure that the attributes were not set with a
+        mix of information from more than one locale.  This would most likely
+        happen when using threads where one thread calls a locale-dependent
+        function while another thread changes the locale while the function in
+        the other thread is still running.  Proper coding would call for
+        locks to prevent changing the locale while locale-dependent code is
+        running.  The check here is done in case someone does not think about
+        doing this.
+
+        Only other possible issue is if someone changed the timezone and did
+        not call tz.tzset .  That is an issue for the programmer, though,
+        since changing the timezone is worthless without that call.
+
+        """
+        self.lang = _getlang()
+        self.__calc_weekday()
+        self.__calc_month()
+        self.__calc_am_pm()
+        self.__calc_timezone()
+        self.__calc_date_time()
+        if _getlang() != self.lang:
+            raise ValueError("locale changed during initialization")
+        if time.tzname != self.tzname or time.daylight != self.daylight:
+            raise ValueError("timezone changed during initialization")
+
+    def __calc_weekday(self):
+        # Set self.a_weekday and self.f_weekday using the calendar
+        # module.
+        a_weekday = [calendar.day_abbr[i].lower() for i in range(7)]
+        f_weekday = [calendar.day_name[i].lower() for i in range(7)]
+        self.a_weekday = a_weekday
+        self.f_weekday = f_weekday
+
+    def __calc_month(self):
+        # Set self.f_month and self.a_month using the calendar module.
+        a_month = [calendar.month_abbr[i].lower() for i in range(13)]
+        f_month = [calendar.month_name[i].lower() for i in range(13)]
+        self.a_month = a_month
+        self.f_month = f_month
+
+    def __calc_am_pm(self):
+        # Set self.am_pm by using time.strftime().
+
+        # The magic date (1999,3,17,hour,44,55,2,76,0) is not really that
+        # magical; just happened to have used it everywhere else where a
+        # static date was needed.
+        am_pm = []
+        for hour in (1, 22):
+            time_tuple = time.struct_time((1999,3,17,hour,44,55,2,76,0))
+            am_pm.append(time.strftime("%p", time_tuple).lower())
+        self.am_pm = am_pm
+
+    def __calc_date_time(self):
+        # Set self.date_time, self.date, & self.time by using
+        # time.strftime().
+
+        # Use (1999,3,17,22,44,55,2,76,0) for magic date because the amount of
+        # overloaded numbers is minimized.  The order in which searches for
+        # values within the format string is very important; it eliminates
+        # possible ambiguity for what something represents.
+        time_tuple = time.struct_time((1999,3,17,22,44,55,2,76,0))
+        date_time = [None, None, None]
+        date_time[0] = time.strftime("%c", time_tuple).lower()
+        date_time[1] = time.strftime("%x", time_tuple).lower()
+        date_time[2] = time.strftime("%X", time_tuple).lower()
+        replacement_pairs = [('%', '%%'), (self.f_weekday[2], '%A'),
+                    (self.f_month[3], '%B'), (self.a_weekday[2], '%a'),
+                    (self.a_month[3], '%b'), (self.am_pm[1], '%p'),
+                    ('1999', '%Y'), ('99', '%y'), ('22', '%H'),
+                    ('44', '%M'), ('55', '%S'), ('76', '%j'),
+                    ('17', '%d'), ('03', '%m'), ('3', '%m'),
+                    # '3' needed for when no leading zero.
+                    ('2', '%w'), ('10', '%I')]
+        replacement_pairs.extend([(tz, "%Z") for tz_values in self.timezone
+                                                for tz in tz_values])
+        for offset,directive in ((0,'%c'), (1,'%x'), (2,'%X')):
+            current_format = date_time[offset]
+            for old, new in replacement_pairs:
+                # Must deal with possible lack of locale info
+                # manifesting itself as the empty string (e.g., Swedish's
+                # lack of AM/PM info) or a platform returning a tuple of empty
+                # strings (e.g., MacOS 9 having timezone as ('','')).
+                if old:
+                    current_format = current_format.replace(old, new)
+            # If %W is used, then Sunday, 2005-01-03 will fall on week 0 since
+            # 2005-01-03 occurs before the first Monday of the year.  Otherwise
+            # %U is used.
+            time_tuple = time.struct_time((1999,1,3,1,1,1,6,3,0))
+            if '00' in time.strftime(directive, time_tuple):
+                U_W = '%W'
+            else:
+                U_W = '%U'
+            date_time[offset] = current_format.replace('11', U_W)
+        self.LC_date_time = date_time[0]
+        self.LC_date = date_time[1]
+        self.LC_time = date_time[2]
+
+    def __calc_timezone(self):
+        # Set self.timezone by using time.tzname.
+        # Do not worry about possibility of time.tzname[0] == time.tzname[1]
+        # and time.daylight; handle that in strptime.
+        try:
+            time.tzset()
+        except AttributeError:
+            pass
+        self.tzname = time.tzname
+        self.daylight = time.daylight
+        no_saving = frozenset({"utc", "gmt", self.tzname[0].lower()})
+        if self.daylight:
+            has_saving = frozenset({self.tzname[1].lower()})
+        else:
+            has_saving = frozenset()
+        self.timezone = (no_saving, has_saving)
+
+
+class TimeRE(dict):
+    """Handle conversion from format directives to regexes."""
+
+    def __init__(self, locale_time=None):
+        """Create keys/values.
+
+        Order of execution is important for dependency reasons.
+
+        """
+        if locale_time:
+            self.locale_time = locale_time
+        else:
+            self.locale_time = LocaleTime()
+        base = super()
+        base.__init__({
+            # The " \d" part of the regex is to make %c from ANSI C work
+            'd': r"(?P<d>3[0-1]|[1-2]\d|0[1-9]|[1-9]| [1-9])",
+            'f': r"(?P<f>[0-9]{1,6})",
+            'H': r"(?P<H>2[0-3]|[0-1]\d|\d)",
+            'I': r"(?P<I>1[0-2]|0[1-9]|[1-9])",
+            'G': r"(?P<G>\d\d\d\d)",
+            'j': r"(?P<j>36[0-6]|3[0-5]\d|[1-2]\d\d|0[1-9]\d|00[1-9]|[1-9]\d|0[1-9]|[1-9])",
+            'm': r"(?P<m>1[0-2]|0[1-9]|[1-9])",
+            'M': r"(?P<M>[0-5]\d|\d)",
+            'S': r"(?P<S>6[0-1]|[0-5]\d|\d)",
+            'U': r"(?P<U>5[0-3]|[0-4]\d|\d)",
+            'w': r"(?P<w>[0-6])",
+            'u': r"(?P<u>[1-7])",
+            'V': r"(?P<V>5[0-3]|0[1-9]|[1-4]\d|\d)",
+            # W is set below by using 'U'
+            'y': r"(?P<y>\d\d)",
+            #XXX: Does 'Y' need to worry about having less or more than
+            #     4 digits?
+            'Y': r"(?P<Y>\d\d\d\d)",
+            'z': r"(?P<z>[+-]\d\d:?[0-5]\d(:?[0-5]\d(\.\d{1,6})?)?|Z)",
+            'A': self.__seqToRE(self.locale_time.f_weekday, 'A'),
+            'a': self.__seqToRE(self.locale_time.a_weekday, 'a'),
+            'B': self.__seqToRE(self.locale_time.f_month[1:], 'B'),
+            'b': self.__seqToRE(self.locale_time.a_month[1:], 'b'),
+            'p': self.__seqToRE(self.locale_time.am_pm, 'p'),
+            'Z': self.__seqToRE((tz for tz_names in self.locale_time.timezone
+                                        for tz in tz_names),
+                                'Z'),
+            '%': '%'})
+        base.__setitem__('W', base.__getitem__('U').replace('U', 'W'))
+        base.__setitem__('c', self.pattern(self.locale_time.LC_date_time))
+        base.__setitem__('x', self.pattern(self.locale_time.LC_date))
+        base.__setitem__('X', self.pattern(self.locale_time.LC_time))
+
+    def __seqToRE(self, to_convert, directive):
+        """Convert a list to a regex string for matching a directive.
+
+        Want possible matching values to be from longest to shortest.  This
+        prevents the possibility of a match occurring for a value that also
+        a substring of a larger value that should have matched (e.g., 'abc'
+        matching when 'abcdef' should have been the match).
+
+        """
+        to_convert = sorted(to_convert, key=len, reverse=True)
+        for value in to_convert:
+            if value != '':
+                break
+        else:
+            return ''
+        regex = '|'.join(re_escape(stuff) for stuff in to_convert)
+        regex = '(?P<%s>%s' % (directive, regex)
+        return '%s)' % regex
+
+    def pattern(self, format):
+        """Return regex pattern for the format string.
+
+        Need to make sure that any characters that might be interpreted as
+        regex syntax are escaped.
+
+        """
+        processed_format = ''
+        # The sub() call escapes all characters that might be misconstrued
+        # as regex syntax.  Cannot use re.escape since we have to deal with
+        # format directives (%m, etc.).
+        regex_chars = re_compile(r"([\\.^$*+?\(\){}\[\]|])")
+        format = regex_chars.sub(r"\\\1", format)
+        whitespace_replacement = re_compile(r'\s+')
+        format = whitespace_replacement.sub(r'\\s+', format)
+        while '%' in format:
+            directive_index = format.index('%')+1
+            processed_format = "%s%s%s" % (processed_format,
+                                           format[:directive_index-1],
+                                           self[format[directive_index]])
+            format = format[directive_index+1:]
+        return "%s%s" % (processed_format, format)
+
+    def compile(self, format):
+        """Return a compiled re object for the format string."""
+        return re_compile(self.pattern(format), IGNORECASE)
+
+_cache_lock = _thread_allocate_lock()
+# DO NOT modify _TimeRE_cache or _regex_cache without acquiring the cache lock
+# first!
+_TimeRE_cache = TimeRE()
+_CACHE_MAX_SIZE = 5 # Max number of regexes stored in _regex_cache
+_regex_cache = {}
+
+def _calc_julian_from_U_or_W(year, week_of_year, day_of_week, week_starts_Mon):
+    """Calculate the Julian day based on the year, week of the year, and day of
+    the week, with week_start_day representing whether the week of the year
+    assumes the week starts on Sunday or Monday (6 or 0)."""
+    first_weekday = datetime_date(year, 1, 1).weekday()
+    # If we are dealing with the %U directive (week starts on Sunday), it's
+    # easier to just shift the view to Sunday being the first day of the
+    # week.
+    if not week_starts_Mon:
+        first_weekday = (first_weekday + 1) % 7
+        day_of_week = (day_of_week + 1) % 7
+    # Need to watch out for a week 0 (when the first day of the year is not
+    # the same as that specified by %U or %W).
+    week_0_length = (7 - first_weekday) % 7
+    if week_of_year == 0:
+        return 1 + day_of_week - first_weekday
+    else:
+        days_to_week = week_0_length + (7 * (week_of_year - 1))
+        return 1 + days_to_week + day_of_week
+
+
+def _calc_julian_from_V(iso_year, iso_week, iso_weekday):
+    """Calculate the Julian day based on the ISO 8601 year, week, and weekday.
+    ISO weeks start on Mondays, with week 01 being the week containing 4 Jan.
+    ISO week days range from 1 (Monday) to 7 (Sunday).
+    """
+    correction = datetime_date(iso_year, 1, 4).isoweekday() + 3
+    ordinal = (iso_week * 7) + iso_weekday - correction
+    # ordinal may be negative or 0 now, which means the date is in the previous
+    # calendar year
+    if ordinal < 1:
+        ordinal += datetime_date(iso_year, 1, 1).toordinal()
+        iso_year -= 1
+        ordinal -= datetime_date(iso_year, 1, 1).toordinal()
+    return iso_year, ordinal
+
+
+def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
+    """Return a 2-tuple consisting of a time struct and an int containing
+    the number of microseconds based on the input string and the
+    format string."""
+
+    for index, arg in enumerate([data_string, format]):
+        if not isinstance(arg, str):
+            msg = "strptime() argument {} must be str, not {}"
+            raise TypeError(msg.format(index, type(arg)))
+
+    global _TimeRE_cache, _regex_cache
+    with _cache_lock:
+        locale_time = _TimeRE_cache.locale_time
+        if (_getlang() != locale_time.lang or
+            time.tzname != locale_time.tzname or
+            time.daylight != locale_time.daylight):
+            _TimeRE_cache = TimeRE()
+            _regex_cache.clear()
+            locale_time = _TimeRE_cache.locale_time
+        if len(_regex_cache) > _CACHE_MAX_SIZE:
+            _regex_cache.clear()
+        format_regex = _regex_cache.get(format)
+        if not format_regex:
+            try:
+                format_regex = _TimeRE_cache.compile(format)
+            # KeyError raised when a bad format is found; can be specified as
+            # \\, in which case it was a stray % but with a space after it
+            except KeyError as err:
+                bad_directive = err.args[0]
+                if bad_directive == "\\":
+                    bad_directive = "%"
+                del err
+                raise ValueError("'%s' is a bad directive in format '%s'" %
+                                    (bad_directive, format)) from None
+            # IndexError only occurs when the format string is "%"
+            except IndexError:
+                raise ValueError("stray %% in format '%s'" % format) from None
+            _regex_cache[format] = format_regex
+    found = format_regex.match(data_string)
+    if not found:
+        raise ValueError("time data %r does not match format %r" %
+                         (data_string, format))
+    if len(data_string) != found.end():
+        raise ValueError("unconverted data remains: %s" %
+                          data_string[found.end():])
+
+    iso_year = year = None
+    month = day = 1
+    hour = minute = second = fraction = 0
+    tz = -1
+    gmtoff = None
+    gmtoff_fraction = 0
+    # Default to -1 to signify that values not known; not critical to have,
+    # though
+    iso_week = week_of_year = None
+    week_of_year_start = None
+    # weekday and julian defaulted to None so as to signal need to calculate
+    # values
+    weekday = julian = None
+    found_dict = found.groupdict()
+    for group_key in found_dict.keys():
+        # Directives not explicitly handled below:
+        #   c, x, X
+        #      handled by making out of other directives
+        #   U, W
+        #      worthless without day of the week
+        if group_key == 'y':
+            year = int(found_dict['y'])
+            # Open Group specification for strptime() states that a %y
+            #value in the range of [00, 68] is in the century 2000, while
+            #[69,99] is in the century 1900
+            if year <= 68:
+                year += 2000
+            else:
+                year += 1900
+        elif group_key == 'Y':
+            year = int(found_dict['Y'])
+        elif group_key == 'G':
+            iso_year = int(found_dict['G'])
+        elif group_key == 'm':
+            month = int(found_dict['m'])
+        elif group_key == 'B':
+            month = locale_time.f_month.index(found_dict['B'].lower())
+        elif group_key == 'b':
+            month = locale_time.a_month.index(found_dict['b'].lower())
+        elif group_key == 'd':
+            day = int(found_dict['d'])
+        elif group_key == 'H':
+            hour = int(found_dict['H'])
+        elif group_key == 'I':
+            hour = int(found_dict['I'])
+            ampm = found_dict.get('p', '').lower()
+            # If there was no AM/PM indicator, we'll treat this like AM
+            if ampm in ('', locale_time.am_pm[0]):
+                # We're in AM so the hour is correct unless we're
+                # looking at 12 midnight.
+                # 12 midnight == 12 AM == hour 0
+                if hour == 12:
+                    hour = 0
+            elif ampm == locale_time.am_pm[1]:
+                # We're in PM so we need to add 12 to the hour unless
+                # we're looking at 12 noon.
+                # 12 noon == 12 PM == hour 12
+                if hour != 12:
+                    hour += 12
+        elif group_key == 'M':
+            minute = int(found_dict['M'])
+        elif group_key == 'S':
+            second = int(found_dict['S'])
+        elif group_key == 'f':
+            s = found_dict['f']
+            # Pad to always return microseconds.
+            s += "0" * (6 - len(s))
+            fraction = int(s)
+        elif group_key == 'A':
+            weekday = locale_time.f_weekday.index(found_dict['A'].lower())
+        elif group_key == 'a':
+            weekday = locale_time.a_weekday.index(found_dict['a'].lower())
+        elif group_key == 'w':
+            weekday = int(found_dict['w'])
+            if weekday == 0:
+                weekday = 6
+            else:
+                weekday -= 1
+        elif group_key == 'u':
+            weekday = int(found_dict['u'])
+            weekday -= 1
+        elif group_key == 'j':
+            julian = int(found_dict['j'])
+        elif group_key in ('U', 'W'):
+            week_of_year = int(found_dict[group_key])
+            if group_key == 'U':
+                # U starts week on Sunday.
+                week_of_year_start = 6
+            else:
+                # W starts week on Monday.
+                week_of_year_start = 0
+        elif group_key == 'V':
+            iso_week = int(found_dict['V'])
+        elif group_key == 'z':
+            z = found_dict['z']
+            if z == 'Z':
+                gmtoff = 0
+            else:
+                if z[3] == ':':
+                    z = z[:3] + z[4:]
+                    if len(z) > 5:
+                        if z[5] != ':':
+                            msg = f"Inconsistent use of : in {found_dict['z']}"
+                            raise ValueError(msg)
+                        z = z[:5] + z[6:]
+                hours = int(z[1:3])
+                minutes = int(z[3:5])
+                seconds = int(z[5:7] or 0)
+                gmtoff = (hours * 60 * 60) + (minutes * 60) + seconds
+                gmtoff_remainder = z[8:]
+                # Pad to always return microseconds.
+                gmtoff_remainder_padding = "0" * (6 - len(gmtoff_remainder))
+                gmtoff_fraction = int(gmtoff_remainder + gmtoff_remainder_padding)
+                if z.startswith("-"):
+                    gmtoff = -gmtoff
+                    gmtoff_fraction = -gmtoff_fraction
+        elif group_key == 'Z':
+            # Since -1 is default value only need to worry about setting tz if
+            # it can be something other than -1.
+            found_zone = found_dict['Z'].lower()
+            for value, tz_values in enumerate(locale_time.timezone):
+                if found_zone in tz_values:
+                    # Deal with bad locale setup where timezone names are the
+                    # same and yet time.daylight is true; too ambiguous to
+                    # be able to tell what timezone has daylight savings
+                    if (time.tzname[0] == time.tzname[1] and
+                       time.daylight and found_zone not in ("utc", "gmt")):
+                        break
+                    else:
+                        tz = value
+                        break
+    # Deal with the cases where ambiguities arize
+    # don't assume default values for ISO week/year
+    if year is None and iso_year is not None:
+        if iso_week is None or weekday is None:
+            raise ValueError("ISO year directive '%G' must be used with "
+                             "the ISO week directive '%V' and a weekday "
+                             "directive ('%A', '%a', '%w', or '%u').")
+        if julian is not None:
+            raise ValueError("Day of the year directive '%j' is not "
+                             "compatible with ISO year directive '%G'. "
+                             "Use '%Y' instead.")
+    elif week_of_year is None and iso_week is not None:
+        if weekday is None:
+            raise ValueError("ISO week directive '%V' must be used with "
+                             "the ISO year directive '%G' and a weekday "
+                             "directive ('%A', '%a', '%w', or '%u').")
+        else:
+            raise ValueError("ISO week directive '%V' is incompatible with "
+                             "the year directive '%Y'. Use the ISO year '%G' "
+                             "instead.")
+
+    leap_year_fix = False
+    if year is None and month == 2 and day == 29:
+        year = 1904  # 1904 is first leap year of 20th century
+        leap_year_fix = True
+    elif year is None:
+        year = 1900
+
+
+    # If we know the week of the year and what day of that week, we can figure
+    # out the Julian day of the year.
+    if julian is None and weekday is not None:
+        if week_of_year is not None:
+            week_starts_Mon = True if week_of_year_start == 0 else False
+            julian = _calc_julian_from_U_or_W(year, week_of_year, weekday,
+                                                week_starts_Mon)
+        elif iso_year is not None and iso_week is not None:
+            year, julian = _calc_julian_from_V(iso_year, iso_week, weekday + 1)
+        if julian is not None and julian <= 0:
+            year -= 1
+            yday = 366 if calendar.isleap(year) else 365
+            julian += yday
+
+    if julian is None:
+        # Cannot pre-calculate datetime_date() since can change in Julian
+        # calculation and thus could have different value for the day of
+        # the week calculation.
+        # Need to add 1 to result since first day of the year is 1, not 0.
+        julian = datetime_date(year, month, day).toordinal() - \
+                  datetime_date(year, 1, 1).toordinal() + 1
+    else:  # Assume that if they bothered to include Julian day (or if it was
+           # calculated above with year/week/weekday) it will be accurate.
+        datetime_result = datetime_date.fromordinal(
+                            (julian - 1) +
+                            datetime_date(year, 1, 1).toordinal())
+        year = datetime_result.year
+        month = datetime_result.month
+        day = datetime_result.day
+    if weekday is None:
+        weekday = datetime_date(year, month, day).weekday()
+    # Add timezone info
+    tzname = found_dict.get("Z")
+
+    if leap_year_fix:
+        # the caller didn't supply a year but asked for Feb 29th. We couldn't
+        # use the default of 1900 for computations. We set it back to ensure
+        # that February 29th is smaller than March 1st.
+        year = 1900
+
+    return (year, month, day,
+            hour, minute, second,
+            weekday, julian, tz, tzname, gmtoff), fraction, gmtoff_fraction
+
+def _strptime_time(data_string, format="%a %b %d %H:%M:%S %Y"):
+    """Return a time struct based on the input string and the
+    format string."""
+    tt = _strptime(data_string, format)[0]
+    return time.struct_time(tt[:time._STRUCT_TM_ITEMS])
+
+def _strptime_datetime(cls, data_string, format="%a %b %d %H:%M:%S %Y"):
+    """Return a class cls instance based on the input string and the
+    format string."""
+    tt, fraction, gmtoff_fraction = _strptime(data_string, format)
+    tzname, gmtoff = tt[-2:]
+    args = tt[:6] + (fraction,)
+    if gmtoff is not None:
+        tzdelta = datetime_timedelta(seconds=gmtoff, microseconds=gmtoff_fraction)
+        if tzname:
+            tz = datetime_timezone(tzdelta, tzname)
+        else:
+            tz = datetime_timezone(tzdelta)
+        args += (tz,)
+
+    return cls(*args)