diff --git a/Lib/test/libregrtest/__init__.py b/Lib/test/libregrtest/__init__.py
new file mode 100644
index 00000000000000..3427b51b60af86
--- /dev/null
+++ b/Lib/test/libregrtest/__init__.py
@@ -0,0 +1,5 @@
+# We import importlib *ASAP* in order to test #15386
+import importlib
+
+from test.libregrtest.cmdline import _parse_args, RESOURCE_NAMES, ALL_RESOURCES
+from test.libregrtest.main import main
diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index f9457203c9d695..c3459345838816 100755
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -207,8 +207,17 @@
 
 from test import support
 
-RESOURCE_NAMES = ('audio', 'curses', 'largefile', 'network',
-                  'decimal', 'cpu', 'subprocess', 'urlfetch', 'gui')
+ALL_RESOURCES = ('audio', 'curses', 'largefile', 'network',
+                 'decimal', 'cpu', 'subprocess', 'urlfetch', 'gui')
+
+# Other resources excluded from --use=all:
+#
+# - extralagefile (ex: test_zipfile64): really too slow to be enabled
+#   "by default"
+# - tzdata: while needed to validate fully test_datetime, it makes
+#   test_datetime too slow (15-20 min on some buildbots) and so is disabled by
+#   default (see bpo-30822).
+RESOURCE_NAMES = ALL_RESOURCES + ('extralargefile', 'tzdata')
 
 # 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
@@ -432,7 +441,7 @@ def _parse_args(args, **kwargs):
         for a in ns.use:
             for r in a:
                 if r == 'all':
-                    ns.use_resources[:] = RESOURCE_NAMES
+                    ns.use_resources[:] = ALL_RESOURCES
                     continue
                 if r == 'none':
                     del ns.use_resources[:]
diff --git a/Lib/test/test_regrtest.py b/Lib/test/test_regrtest.py
index 0eb3f08fe7b21a..dc5899203cbc4d 100644
--- a/Lib/test/test_regrtest.py
+++ b/Lib/test/test_regrtest.py
@@ -192,15 +192,26 @@ def test_use(self):
             with self.subTest(opt=opt):
                 ns = regrtest._parse_args([opt, 'gui,network'])
                 self.assertEqual(ns.use_resources, ['gui', 'network'])
+
                 ns = regrtest._parse_args([opt, 'gui,none,network'])
                 self.assertEqual(ns.use_resources, ['network'])
-                expected = list(regrtest.RESOURCE_NAMES)
+
+                expected = list(regrtest.ALL_RESOURCES)
                 expected.remove('gui')
                 ns = regrtest._parse_args([opt, 'all,-gui'])
                 self.assertEqual(ns.use_resources, expected)
                 self.checkError([opt], 'expected one argument')
                 self.checkError([opt, 'foo'], 'invalid resource')
 
+                # all + a resource not part of "all"
+                ns = regrtest._parse_args([opt, 'all,tzdata'])
+                self.assertEqual(ns.use_resources,
+                                 list(regrtest.ALL_RESOURCES) + ['tzdata'])
+
+                # test another resource which is not part of "all"
+                ns = regrtest._parse_args([opt, 'extralargefile'])
+                self.assertEqual(ns.use_resources, ['extralargefile'])
+
     def test_memlimit(self):
         for opt in '-M', '--memlimit':
             with self.subTest(opt=opt):
diff --git a/Misc/NEWS.d/next/Tests/2017-07-20-14-29-54.bpo-30822.X0wREo.rst b/Misc/NEWS.d/next/Tests/2017-07-20-14-29-54.bpo-30822.X0wREo.rst
new file mode 100644
index 00000000000000..53557f66feffa9
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2017-07-20-14-29-54.bpo-30822.X0wREo.rst
@@ -0,0 +1,5 @@
+regrtest: Exclude tzdata from regrtest --all. When running the test suite
+using --use=all / -u all, exclude tzdata since it makes test_datetime too
+slow (15-20 min on some buildbots) which then times out on some buildbots.
+Fix also regrtest command line parser to allow passing -u extralargefile to
+run test_zipfile64.