diff --git a/stestr/commands/run.py b/stestr/commands/run.py
index 8c02b24..a1ca9f5 100644
--- a/stestr/commands/run.py
+++ b/stestr/commands/run.py
@@ -18,6 +18,7 @@
 import os
 import subprocess
 import sys
+import warnings
 
 from cliff import command
 import subunit
@@ -244,6 +245,12 @@ def get_parser(self, prog_name):
             help="If set, show non-text attachments. This is "
             "generally only useful for debug purposes.",
         )
+        parser.add_argument(
+            "--dynamic",
+            action="store_true",
+            default=False,
+            help="Enable the EXPERIMENTAL dynamic scheduler",
+        )
         return parser
 
     def take_action(self, parsed_args):
@@ -335,6 +342,7 @@ def take_action(self, parsed_args):
             all_attachments=all_attachments,
             show_binary_attachments=args.show_binary_attachments,
             pdb=args.pdb,
+            dynamic=args.dynamic,
         )
 
         # Always output slowest test info if requested, regardless of other
@@ -396,6 +404,7 @@ def run_command(
     all_attachments=False,
     show_binary_attachments=True,
     pdb=False,
+    dynamic=False,
 ):
     """Function to execute the run command
 
@@ -460,6 +469,7 @@ def run_command(
     :param str pdb: Takes in a single test_id to bypasses test
         discover and just execute the test specified without launching any
         additional processes. A file name may be used in place of a test name.
+    :param bool dynamic: Enable dynamic scheduling
 
     :return return_code: The exit code for the command. 0 for success and > 0
         for failures.
@@ -501,6 +511,11 @@ def run_command(
         )
         stdout.write(msg)
         return 2
+    if dynamic:
+        warnings.warn(
+            "WARNING: The dynamic scheduler is still experimental. "
+            "You might encounter issues while using it"
+        )
     if combine:
         latest_id = repo.latest_id()
         combine_id = str(latest_id)
@@ -542,7 +557,8 @@ def run_tests():
                 (
                     "subunit",
                     output.ReturnCodeToSubunit(
-                        subprocess.Popen(run_cmd, shell=True, stdout=subprocess.PIPE)
+                        subprocess.Popen(run_cmd, shell=True, stdout=subprocess.PIPE),
+                        dynamic=False,
                     ),
                 )
             ]
@@ -645,6 +661,7 @@ def run_tests():
             top_dir=top_dir,
             test_path=test_path,
             randomize=random,
+            dynamic=dynamic,
         )
         if isolated:
             result = 0
@@ -684,6 +701,7 @@ def run_tests():
                     suppress_attachments=suppress_attachments,
                     all_attachments=all_attachments,
                     show_binary_attachments=show_binary_attachments,
+                    dynamic=dynamic,
                 )
                 if run_result > result:
                     result = run_result
@@ -702,6 +720,7 @@ def run_tests():
                 suppress_attachments=suppress_attachments,
                 all_attachments=all_attachments,
                 show_binary_attachments=show_binary_attachments,
+                dynamic=dynamic,
             )
     else:
         # Where do we source data about the cause of conflicts.
@@ -771,16 +790,28 @@ def _run_tests(
     suppress_attachments=False,
     all_attachments=False,
     show_binary_attachments=False,
+    dynamic=False,
 ):
     """Run the tests cmd was parameterised with."""
     cmd.setUp()
     try:
 
         def run_tests():
-            run_procs = [
-                ("subunit", output.ReturnCodeToSubunit(proc))
-                for proc in cmd.run_tests()
-            ]
+            if not dynamic or cmd.concurrency == 1:
+                run_procs = [
+                    ("subunit", output.ReturnCodeToSubunit(proc, dynamic=False))
+                    for proc in cmd.run_tests()
+                ]
+            else:
+                run_procs = [
+                    (
+                        "subunit",
+                        output.ReturnCodeToSubunit(
+                            os.fdopen(proc["stream"]), proc["proc"]
+                        ),
+                    )
+                    for proc in cmd.run_tests()
+                ]
             if not run_procs:
                 stdout.write("The specified regex doesn't match with anything")
                 return 1
diff --git a/stestr/config_file.py b/stestr/config_file.py
index 6a66503..215be27 100644
--- a/stestr/config_file.py
+++ b/stestr/config_file.py
@@ -113,6 +113,7 @@ def get_run_command(
         exclude_regex=None,
         randomize=False,
         parallel_class=None,
+        dynamic=False,
     ):
         """Get a test_processor.TestProcessorFixture for this config file
 
@@ -158,6 +159,7 @@ def get_run_command(
             stestr scheduler by class. If both this and the corresponding
             config file option which includes `group-regex` are set, this value
             will be used.
+        :param bool dynamic: Enable dynamic scheduling
 
         :returns: a TestProcessorFixture object for the specified config file
             and any arguments passed into this function
@@ -236,4 +238,5 @@ def group_callback(test_id, regex=re.compile(group_regex)):
             exclude_regex=exclude_regex,
             include_list=include_list,
             randomize=randomize,
+            dynamic=dynamic,
         )
diff --git a/stestr/output.py b/stestr/output.py
index 9af043e..b194859 100644
--- a/stestr/output.py
+++ b/stestr/output.py
@@ -164,21 +164,33 @@ class ReturnCodeToSubunit:
         generating subunit.
     """
 
-    def __init__(self, process):
+    def __init__(self, process, thread=None, dynamic=True):
         """Adapt a process to a readable stream."""
         self.proc = process
         self.done = False
-        self.source = self.proc.stdout
+        if dynamic:
+            self.source = process
+            self.proc = thread
+        else:
+            self.source = self.proc.stdout
+        self.dynamic = dynamic
         self.lastoutput = bytes((b"\n")[0])
 
     def __del__(self):
-        self.proc.wait()
+        if hasattr(self.proc, "wait"):
+            self.proc.wait()
+        else:
+            self.proc.join()
 
     def _append_return_code_as_test(self):
         if self.done is True:
             return
         self.source = io.BytesIO()
-        returncode = self.proc.wait()
+        if not self.dynamic:
+            returncode = self.proc.wait()
+        else:
+            self.proc.join()
+            returncode = self.proc.exitcode
         if returncode != 0:
             if self.lastoutput != bytes((b"\n")[0]):
                 # Subunit V1 is line orientated, it has to start on a fresh
diff --git a/stestr/scheduler.py b/stestr/scheduler.py
index e5816c1..bb7a2ac 100644
--- a/stestr/scheduler.py
+++ b/stestr/scheduler.py
@@ -21,6 +21,74 @@
 from stestr import selection
 
 
+def get_dynamic_test_list(
+    test_ids, repository=None, group_callback=None, randomize=False
+):
+    dynamic_test_list = []
+    _group_callback = group_callback
+    time_data = {}
+    if randomize:
+        return random.shuffle(test_ids)
+    if repository:
+        time_data = repository.get_test_times(test_ids)
+        timed_tests = time_data["known"]
+        unknown_tests = time_data["unknown"]
+    else:
+        timed_tests = {}
+        unknown_tests = set(test_ids)
+    # Group tests: generate group_id -> test_ids.
+    group_ids = collections.defaultdict(list)
+    if _group_callback is None:
+
+        def group_callback(_):
+            return None
+
+    else:
+        group_callback = _group_callback
+    for test_id in test_ids:
+        group_id = group_callback(test_id) or test_id
+        group_ids[group_id].append(test_id)
+    # Time groups: generate three sets of groups:
+    # - fully timed dict(group_id -> time),
+    # - partially timed dict(group_id -> time) and
+    # - unknown (set of group_id)
+    # We may in future treat partially timed different for scheduling, but
+    # at least today we just schedule them after the fully timed groups.
+    timed = {}
+    partial = {}
+    unknown = []
+    for group_id, group_tests in group_ids.items():
+        untimed_ids = unknown_tests.intersection(group_tests)
+        group_time = sum(
+            [
+                timed_tests[test_id]
+                for test_id in untimed_ids.symmetric_difference(group_tests)
+            ]
+        )
+        if not untimed_ids:
+            timed[group_id] = group_time
+        elif group_time:
+            partial[group_id] = group_time
+        else:
+            unknown.append(group_id)
+
+    # Scheduling is NP complete in general, so we avoid aiming for
+    # perfection. A quick approximation that is sufficient for our general
+    # needs:
+    # sort the groups by time
+    # allocate to partitions by putting each group in to the partition with
+    # the current (lowest time, shortest length[in tests])
+    def consume_queue(groups):
+        queue = sorted(groups.items(), key=operator.itemgetter(1), reverse=True)
+        dynamic_test_list.extend([group[0] for group in queue])
+
+    consume_queue(timed)
+    consume_queue(partial)
+    dynamic_test_list.extend(unknown)
+
+    return dynamic_test_list
+
+
 def partition_tests(test_ids, concurrency, repository, group_callback, randomize=False):
     """Partition test_ids by concurrency.
 
diff --git a/stestr/test_processor.py b/stestr/test_processor.py
index f52596a..dd2ce8e 100644
--- a/stestr/test_processor.py
+++ b/stestr/test_processor.py
@@ -10,7 +10,9 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import functools
 import io
+import multiprocessing
 import os
 import re
 import signal
@@ -24,6 +26,8 @@
 from stestr import results
 from stestr import scheduler
 from stestr import selection
+from stestr.subunit_runner import program
+from stestr.subunit_runner import run
 from stestr import testlist
 
 
@@ -94,6 +98,7 @@ def __init__(
         exclude_regex=None,
         include_list=None,
         randomize=False,
+        dynamic=False,
     ):
         """Create a TestProcessorFixture."""
 
@@ -115,6 +120,7 @@ def __init__(
         self.include_list = include_list
         self.exclude_regex = exclude_regex
         self.randomize = randomize
+        self.dynamic = dynamic
 
     def setUp(self):
         super().setUp()
@@ -249,6 +255,31 @@ def list_tests(self):
         ids = testlist.parse_enumeration(out)
         return ids
 
+    def _dynamic_run_tests(self, job_queue, subunit_pipe):
+        while True:
+            # NOTE(mtreinish): Open on each loop iteration with a dup to
+            # remove the chance of being garbage collected. Without this
+            # you'll be fighting random Bad file desciptor errors
+            subunit_pipe = os.fdopen(os.dup(subunit_pipe.fileno()), "wb")
+            if job_queue.empty():
+                subunit_pipe.close()
+                return
+            try:
+                test_id = job_queue.get(block=False)
+            except Exception:
+                subunit_pipe.close()
+                return
+            if not test_id:
+                os.close(subunit_pipe.fileno())
+                raise ValueError("Invalid blank test_id: %s" % test_id)
+            cmd_list = [self.cmd, test_id]
+            test_runner = run.SubunitTestRunner
+            program.TestProgram(
+                module=None,
+                argv=cmd_list,
+                testRunner=functools.partial(test_runner, stdout=subunit_pipe),
+            )
+
     def run_tests(self):
         """Run the tests defined by the command
 
@@ -280,19 +311,41 @@ def run_tests(self):
             test_id_groups = scheduler.partition_tests(
                 test_ids, self.concurrency, self.repository, self._group_callback
             )
-        for test_ids in test_id_groups:
-            if not test_ids:
-                # No tests in this partition
-                continue
-            fixture = self.useFixture(
-                TestProcessorFixture(
-                    test_ids,
-                    self.template,
-                    self.listopt,
-                    self.idoption,
-                    self.repository,
-                    parallel=False,
+        if not self.dynamic:
+            for test_ids in test_id_groups:
+                if not test_ids:
+                    # No tests in this partition
+                    continue
+                fixture = self.useFixture(
+                    TestProcessorFixture(
+                        test_ids,
+                        self.template,
+                        self.listopt,
+                        self.idoption,
+                        self.repository,
+                        parallel=False,
+                    )
                 )
+                result.extend(fixture.run_tests())
+            return result
+        else:
+            test_id_list = scheduler.get_dynamic_test_list(
+                test_ids, self.repository, self._group_callback
             )
-            result.extend(fixture.run_tests())
-        return result
+            test_list = multiprocessing.Queue()
+
+            for test_id in test_id_list:
+                test_list.put(test_id)
+
+            for i in range(self.concurrency):
+                fd_pipe_r, fd_pipe_w = multiprocessing.Pipe(False)
+                name = "worker-%s" % i
+                proc = multiprocessing.Process(
+                    target=self._dynamic_run_tests,
+                    name=name,
+                    args=(test_list, fd_pipe_w),
+                )
+                proc.start()
+                stream_read = os.dup(fd_pipe_r.fileno())
+                result.append({"stream": stream_read, "proc": proc})
+            return result
diff --git a/stestr/tests/test_config_file.py b/stestr/tests/test_config_file.py
index a1a1e9d..73f522f 100644
--- a/stestr/tests/test_config_file.py
+++ b/stestr/tests/test_config_file.py
@@ -74,6 +74,7 @@ def _check_get_run_command(
             exclude_regex=None,
             exclude_list=None,
             concurrency=0,
+            dynamic=False,
             group_callback=expected_group_callback,
             test_filters=None,
             randomize=False,
diff --git a/stestr/tests/test_return_codes.py b/stestr/tests/test_return_codes.py
index 99c1e3c..f102607 100644
--- a/stestr/tests/test_return_codes.py
+++ b/stestr/tests/test_return_codes.py
@@ -94,7 +94,6 @@ def assertRunExit(self, cmd, expected, subunit=False, stdin=None):
                 "%s" % cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
             )
             out, err = p.communicate()
-
         if not subunit:
             self.assertEqual(
                 p.returncode, expected, "Stdout: {}; Stderr: {}".format(out, err)
diff --git a/tox.ini b/tox.ini
index 4730fba..8d76811 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,7 +14,7 @@ deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands =
     python tools/find_and_rm.py
-    stestr run {posargs}
+    stestr run --dynamic {posargs}
 
 [testenv:pep8]
 sitepackages = False