diff --git a/buildstream/_artifactcache/artifactcache.py b/buildstream/_artifactcache/artifactcache.py
index 7080f2151fbacc89cf4c61f102dafd7d36effc8d..bfa705127bd31a97763b21427417143a3de03c16 100644
--- a/buildstream/_artifactcache/artifactcache.py
+++ b/buildstream/_artifactcache/artifactcache.py
@@ -835,6 +835,20 @@ class ArtifactCache():
 
         self.cas.link_ref(oldref, newref)
 
+    # checkout_artifact_subdir()
+    #
+    # Checkout given artifact subdir into provided directory
+    #
+    # Args:
+    #     element (Element): The Element
+    #     key (str): The cache key to use
+    #     subdir (str): The subdir to checkout
+    #     tmpdir (str): The dir to place the subdir content
+    #
+    def checkout_artifact_subdir(self, element, key, subdir, tmpdir):
+        ref = self.get_artifact_fullname(element, key)
+        return self.cas.checkout_artifact_subdir(ref, subdir, tmpdir)
+
     ################################################
     #               Local Private Methods          #
     ################################################
diff --git a/buildstream/_artifactcache/cascache.py b/buildstream/_artifactcache/cascache.py
index f07bd24a11701e91cf8d80bdaad548c00589c668..2962c9fa4945db3446ad6cced22440b234d88389 100644
--- a/buildstream/_artifactcache/cascache.py
+++ b/buildstream/_artifactcache/cascache.py
@@ -409,6 +409,21 @@ class CASCache():
 
         return True
 
+    # checkout_artifact_subdir():
+    #
+    # Checkout given artifact subdir into provided directory
+    #
+    # Args:
+    #     ref (str): The ref to check
+    #     subdir (str): The subdir to checkout
+    #     tmpdir (str): The dir to place the subdir content
+    #
+    def checkout_artifact_subdir(self, ref, subdir, tmpdir):
+        tree = self.resolve_ref(ref)
+        # This assumes that the subdir digest is present in the element tree
+        subdirdigest = self._get_subdir(tree, subdir)
+        self._checkout(tmpdir, subdirdigest)
+
     # objpath():
     #
     # Return the path of an object based on its digest.
diff --git a/buildstream/_context.py b/buildstream/_context.py
index d4c338f0768b84675fd4bb6ae5ffbafa7539775c..33744af63f5eb1cc650d93587da533464a05e832 100644
--- a/buildstream/_context.py
+++ b/buildstream/_context.py
@@ -107,6 +107,9 @@ class Context():
         # Whether or not to attempt to pull build trees globally
         self.pull_build_trees = False
 
+        # Whether to not include artifact buildtrees in workspaces if available
+        self.workspace_build_trees = True
+
         # Whether elements must be rebuilt when their dependencies have changed
         self._strict_build_plan = None
 
@@ -163,7 +166,7 @@ class Context():
         _yaml.node_validate(defaults, [
             'sourcedir', 'builddir', 'artifactdir', 'logdir',
             'scheduler', 'artifacts', 'logging', 'projects',
-            'cache', 'pullbuildtrees'
+            'cache', 'pullbuildtrees', 'workspacebuildtrees'
         ])
 
         for directory in ['sourcedir', 'builddir', 'artifactdir', 'logdir']:
@@ -191,6 +194,9 @@ class Context():
         # Load pull build trees configuration
         self.pull_build_trees = _yaml.node_get(defaults, bool, 'pullbuildtrees', default_value='False')
 
+        # Load workspace buildtrees configuration
+        self.workspace_build_trees = _yaml.node_get(defaults, bool, 'workspacebuildtrees', default_value='True')
+
         # Load logging config
         logging = _yaml.node_get(defaults, Mapping, 'logging')
         _yaml.node_validate(logging, [
diff --git a/buildstream/_frontend/cli.py b/buildstream/_frontend/cli.py
index f019058283d9b71c9acfbb9aeb4043df362f5f78..b62cb5b9ea76ce774b55ff4b1e8874dd7e6a1e62 100644
--- a/buildstream/_frontend/cli.py
+++ b/buildstream/_frontend/cli.py
@@ -678,17 +678,21 @@ def workspace():
 ##################################################################
 @workspace.command(name='open', short_help="Open a new workspace")
 @click.option('--no-checkout', default=False, is_flag=True,
-              help="Do not checkout the source, only link to the given directory")
+              help="Do not checkout the source or cached buildtree, only link to the given directory")
 @click.option('--force', '-f', default=False, is_flag=True,
               help="Overwrite files existing in checkout directory")
 @click.option('--track', 'track_', default=False, is_flag=True,
               help="Track and fetch new source references before checking out the workspace")
+@click.option('--no-cache', default=False, is_flag=True,
+              help="Do not checkout the cached buildtree")
 @click.argument('element',
                 type=click.Path(readable=False))
 @click.argument('directory', type=click.Path(file_okay=False))
 @click.pass_obj
-def workspace_open(app, no_checkout, force, track_, element, directory):
-    """Open a workspace for manual source modification"""
+def workspace_open(app, no_checkout, force, track_, no_cache, element, directory):
+    """Open a workspace for manual source modification, the elements buildtree
+    will be provided if available in the local artifact cache.
+    """
 
     if os.path.exists(directory):
 
@@ -700,11 +704,15 @@ def workspace_open(app, no_checkout, force, track_, element, directory):
             click.echo("Checkout directory is not empty: {}".format(directory), err=True)
             sys.exit(-1)
 
+    if not no_cache and not no_checkout:
+        click.echo("WARNING: Workspace will be opened without the cached buildtree if not cached locally")
+
     with app.initialized():
         app.stream.workspace_open(element, directory,
                                   no_checkout=no_checkout,
                                   track_first=track_,
-                                  force=force)
+                                  force=force,
+                                  no_cache=no_cache)
 
 
 ##################################################################
diff --git a/buildstream/_stream.py b/buildstream/_stream.py
index 6e2e8b25b24c4a67670a36f401d0267ea3210373..f921718998875037de45027ce12ba6e858b6fe70 100644
--- a/buildstream/_stream.py
+++ b/buildstream/_stream.py
@@ -453,11 +453,17 @@ class Stream():
     #    no_checkout (bool): Whether to skip checking out the source
     #    track_first (bool): Whether to track and fetch first
     #    force (bool): Whether to ignore contents in an existing directory
+    #    no_cache (bool): Whether to not include the cached buildtree
     #
     def workspace_open(self, target, directory, *,
                        no_checkout,
                        track_first,
-                       force):
+                       force,
+                       no_cache):
+
+        # Override no_cache if the global user conf workspacebuildtrees is false
+        if not self._context.workspace_build_trees:
+            no_cache = True
 
         if track_first:
             track_targets = (target,)
@@ -470,6 +476,20 @@ class Stream():
         target = elements[0]
         directory = os.path.abspath(directory)
 
+        # Check if given target has a buildtree artifact cached locally
+        buildtree = None
+        if target._cached():
+            buildtree = self._artifacts.contains_subdir_artifact(target, target._get_cache_key(), 'buildtree')
+
+        # If we're running in the default state, make the user aware of buildtree usage
+        if not no_cache and not no_checkout:
+            if buildtree:
+                self._message(MessageType.INFO, "{} buildtree artifact is available,"
+                              " workspace will be opened with it".format(target.name))
+            else:
+                self._message(MessageType.WARN, "{} buildtree artifact not available,"
+                              " workspace will be opened with source checkout".format(target.name))
+
         if not list(target.sources()):
             build_depends = [x.name for x in target.dependencies(Scope.BUILD, recurse=False)]
             if not build_depends:
@@ -501,6 +521,7 @@ class Stream():
                               "fetch the latest version of the " +
                               "source.")
 
+        # Presume workspace to be forced if previous StreamError not raised
         if workspace:
             workspaces.delete_workspace(target._get_full_name())
             workspaces.save_config()
@@ -510,11 +531,16 @@ class Stream():
         except OSError as e:
             raise StreamError("Failed to create workspace directory: {}".format(e)) from e
 
-        workspaces.create_workspace(target._get_full_name(), directory)
-
-        if not no_checkout:
-            with target.timed_activity("Staging sources to {}".format(directory)):
-                target._open_workspace()
+        # Handle opening workspace with buildtree included
+        if (buildtree and not no_cache) and not no_checkout:
+            workspaces.create_workspace(target._get_full_name(), directory, cached_build=buildtree)
+            with target.timed_activity("Staging buildtree to {}".format(directory)):
+                target._open_workspace(buildtree=buildtree)
+        else:
+            workspaces.create_workspace(target._get_full_name(), directory)
+            if (not buildtree or no_cache) and not no_checkout:
+                with target.timed_activity("Staging sources to {}".format(directory)):
+                    target._open_workspace()
 
         workspaces.save_config()
         self._message(MessageType.INFO, "Saved workspace configuration")
@@ -598,10 +624,24 @@ class Stream():
                                       .format(workspace_path, e)) from e
 
             workspaces.delete_workspace(element._get_full_name())
-            workspaces.create_workspace(element._get_full_name(), workspace_path)
 
-            with element.timed_activity("Staging sources to {}".format(workspace_path)):
-                element._open_workspace()
+            # Create the workspace, ensuring the original optional cached build state is preserved if
+            # possible.
+            buildtree = False
+            if workspace.cached_build and element._cached():
+                if self._artifacts.contains_subdir_artifact(element, element._get_cache_key(), 'buildtree'):
+                    buildtree = True
+
+            # Warn the user if the workspace cannot be opened with the original cached build state
+            if workspace.cached_build and not buildtree:
+                self._message(MessageType.WARN, "{} original buildtree artifact not available,"
+                              " workspace will be opened with source checkout".format(element.name))
+
+            workspaces.create_workspace(element._get_full_name(), workspace_path,
+                                        cached_build=buildtree)
+
+            with element.timed_activity("Staging to {}".format(workspace_path)):
+                element._open_workspace(buildtree=buildtree)
 
             self._message(MessageType.INFO,
                           "Reset workspace for {} at: {}".format(element.name,
diff --git a/buildstream/_workspaces.py b/buildstream/_workspaces.py
index 468073f0584826e8aaf8aed47ec7cb90d9667fed..6e246e0a655709ee7ecba139897b63749b42c73e 100644
--- a/buildstream/_workspaces.py
+++ b/buildstream/_workspaces.py
@@ -24,7 +24,7 @@ from . import _yaml
 from ._exceptions import LoadError, LoadErrorReason
 
 
-BST_WORKSPACE_FORMAT_VERSION = 3
+BST_WORKSPACE_FORMAT_VERSION = 4
 
 
 # Workspace()
@@ -43,9 +43,11 @@ BST_WORKSPACE_FORMAT_VERSION = 3
 #    running_files (dict): A dict mapping dependency elements to files
 #                          changed between failed builds. Should be
 #                          made obsolete with failed build artifacts.
+#    cached_build (bool): If the workspace is staging the cached build artifact
 #
 class Workspace():
-    def __init__(self, toplevel_project, *, last_successful=None, path=None, prepared=False, running_files=None):
+    def __init__(self, toplevel_project, *, last_successful=None, path=None, prepared=False,
+                 running_files=None, cached_build=False):
         self.prepared = prepared
         self.last_successful = last_successful
         self._path = path
@@ -53,6 +55,7 @@ class Workspace():
 
         self._toplevel_project = toplevel_project
         self._key = None
+        self.cached_build = cached_build
 
     # to_dict()
     #
@@ -65,7 +68,8 @@ class Workspace():
         ret = {
             'prepared': self.prepared,
             'path': self._path,
-            'running_files': self.running_files
+            'running_files': self.running_files,
+            'cached_build': self.cached_build
         }
         if self.last_successful is not None:
             ret["last_successful"] = self.last_successful
@@ -224,12 +228,13 @@ class Workspaces():
     # Args:
     #    element_name (str) - The element name to create a workspace for
     #    path (str) - The path in which the workspace should be kept
+    #    cached_build (bool) - If the workspace is staging the cached build artifact
     #
-    def create_workspace(self, element_name, path):
+    def create_workspace(self, element_name, path, cached_build=False):
         if path.startswith(self._toplevel_project.directory):
             path = os.path.relpath(path, self._toplevel_project.directory)
 
-        self._workspaces[element_name] = Workspace(self._toplevel_project, path=path)
+        self._workspaces[element_name] = Workspace(self._toplevel_project, path=path, cached_build=cached_build)
 
         return self._workspaces[element_name]
 
@@ -396,6 +401,7 @@ class Workspaces():
             'path': _yaml.node_get(node, str, 'path'),
             'last_successful': _yaml.node_get(node, str, 'last_successful', default_value=None),
             'running_files': _yaml.node_get(node, dict, 'running_files', default_value=None),
+            'cached_build': _yaml.node_get(node, bool, 'cached_build', default_value=False)
         }
         return Workspace.from_dict(self._toplevel_project, dictionary)
 
diff --git a/buildstream/element.py b/buildstream/element.py
index 792be3fdb4275c4bd8ed7464bbef4caf95278399..d572d7c7c0d725a4cf55b72d9507b7baf32ec86c 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -1896,7 +1896,10 @@ class Element(Plugin):
     # This requires that a workspace already be created in
     # the workspaces metadata first.
     #
-    def _open_workspace(self):
+    # Args:
+    #    buildtree (bool): Whether to open workspace with artifact buildtree
+    #
+    def _open_workspace(self, buildtree=False):
         context = self._get_context()
         workspace = self._get_workspace()
         assert workspace is not None
@@ -1909,12 +1912,22 @@ class Element(Plugin):
         # files in the target directory actually works without any
         # additional support from Source implementations.
         #
+
         os.makedirs(context.builddir, exist_ok=True)
-        with utils._tempdir(dir=context.builddir, prefix='workspace-{}'
-                            .format(self.normal_name)) as temp:
+        with utils._tempdir(dir=context.builddir, prefix='workspace-source-{}'
+                            .format(self.normal_name)) as temp,\
+            utils._tempdir(dir=context.builddir, prefix='workspace-buildtree-{}'
+                           .format(self.normal_name)) as buildtreetemp:
+
             for source in self.sources():
                 source._init_workspace(temp)
 
+            # Overwrite the source checkout with the cached buildtree
+            if buildtree:
+                self.__artifacts.checkout_artifact_subdir(self, self._get_cache_key(), 'buildtree', buildtreetemp)
+                if utils._call([utils.get_host_tool('cp'), '-pfr', "".join((buildtreetemp, '/.')), temp])[0] != 0:
+                    raise ElementError("Failed to copy buildtree into workspace checkout at {}".format(buildtreetemp))
+
             # Now hardlink the files into the workspace target.
             utils.link_files(temp, workspace.get_absolute_path())
 
diff --git a/doc/source/developing/workspaces.rst b/doc/source/developing/workspaces.rst
index b5ed64b2c62c6f958c6c47a13d2cd62c381464e4..4b68b24d566343acb0576f76122d5873f03a3a4d 100644
--- a/doc/source/developing/workspaces.rst
+++ b/doc/source/developing/workspaces.rst
@@ -24,9 +24,32 @@ Suppose we now want to alter the functionality of the *hello* command. We can
 make changes to the source code of Buildstream elements by making use of
 BuildStream's workspace command.
 
+Utilising cached buildtrees
+---------------------------
+ When a BuildStream build element artifact is created and cached, a snapshot of
+ the build directory after the build commands have completed is included in the
+ artifact. This `build tree` can be considered an intermediary state of element,
+ where the source is present along with any output created during the build
+ execution.
+
+ By default when opening a workspace, bst will attempt to stage the build tree
+ into the workspace if it's available in the local cache. If the respective
+ build tree is not present in the cache (element not cached, partially cached or
+ is a non build element) then the source will be staged as is. The default
+ behaviour to attempt to use the build tree can be overriden with specific bst
+ workspace open option of `--no-cache`, or via setting user configuration option
+ `workspacebuildtrees: False`
+
 
 Opening a workspace
 -------------------
+.. note::
+
+    This example presumes you built the hello.bst during
+    :ref:`running commands <tutorial_running_commands>`
+    if not, please start by building it.
+
+
 First we need to open a workspace, we can do this by running
 
 .. raw:: html
@@ -88,6 +111,15 @@ Alternatively, if we wish to discard the changes we can use
 
 This resets the workspace to its original state.
 
+.. note::
+
+    bst reset will attempt to open the workspace in
+    the condition in which it was originally staged,
+    i.e with or without consuming the element build tree.
+    If it was originally staged with a cached build tree
+    and there's no longer one available, the source will
+    be staged as is.
+
 To discard the workspace completely we can do:
 
 .. raw:: html
diff --git a/tests/frontend/workspace.py b/tests/frontend/workspace.py
index 51b7d608894dd5fac55af329b55e4f67a87cf8ac..26535e4ab9020e80df6da98982668033ee4cda6e 100644
--- a/tests/frontend/workspace.py
+++ b/tests/frontend/workspace.py
@@ -44,7 +44,7 @@ DATA_DIR = os.path.join(
 
 
 def open_workspace(cli, tmpdir, datafiles, kind, track, suffix='', workspace_dir=None,
-                   project_path=None, element_attrs=None):
+                   project_path=None, element_attrs=None, no_cache=False):
     if not workspace_dir:
         workspace_dir = os.path.join(str(tmpdir), 'workspace{}'.format(suffix))
     if not project_path:
@@ -88,6 +88,8 @@ def open_workspace(cli, tmpdir, datafiles, kind, track, suffix='', workspace_dir
     args = ['workspace', 'open']
     if track:
         args.append('--track')
+    if no_cache:
+        args.append('--no-cache')
     args.extend([element_name, workspace_dir])
     result = cli.run(project=project_path, args=args)
 
@@ -101,7 +103,7 @@ def open_workspace(cli, tmpdir, datafiles, kind, track, suffix='', workspace_dir
     filename = os.path.join(workspace_dir, 'usr', 'bin', 'hello')
     assert os.path.exists(filename)
 
-    return (element_name, project_path, workspace_dir)
+    return (element_name, project_path, workspace_dir, result)
 
 
 @pytest.mark.datafiles(DATA_DIR)
@@ -112,7 +114,7 @@ def test_open(cli, tmpdir, datafiles, kind):
 
 @pytest.mark.datafiles(DATA_DIR)
 def test_open_bzr_customize(cli, tmpdir, datafiles):
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, "bzr", False)
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, "bzr", False)
 
     # Check that the .bzr dir exists
     bzrdir = os.path.join(workspace, ".bzr")
@@ -137,7 +139,7 @@ def test_open_track(cli, tmpdir, datafiles, kind):
 @pytest.mark.datafiles(DATA_DIR)
 @pytest.mark.parametrize("kind", repo_kinds)
 def test_open_force(cli, tmpdir, datafiles, kind):
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, kind, False)
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, kind, False)
 
     # Close the workspace
     result = cli.run(project=project, args=[
@@ -158,7 +160,7 @@ def test_open_force(cli, tmpdir, datafiles, kind):
 @pytest.mark.datafiles(DATA_DIR)
 @pytest.mark.parametrize("kind", repo_kinds)
 def test_open_force_open(cli, tmpdir, datafiles, kind):
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, kind, False)
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, kind, False)
 
     # Assert the workspace dir exists
     assert os.path.exists(workspace)
@@ -173,7 +175,7 @@ def test_open_force_open(cli, tmpdir, datafiles, kind):
 @pytest.mark.datafiles(DATA_DIR)
 @pytest.mark.parametrize("kind", repo_kinds)
 def test_open_force_different_workspace(cli, tmpdir, datafiles, kind):
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, kind, False, "-alpha")
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, kind, False, "-alpha")
 
     # Assert the workspace dir exists
     assert os.path.exists(workspace)
@@ -183,7 +185,7 @@ def test_open_force_different_workspace(cli, tmpdir, datafiles, kind):
 
     tmpdir = os.path.join(str(tmpdir), "-beta")
     shutil.move(hello_path, hello1_path)
-    element_name2, project2, workspace2 = open_workspace(cli, tmpdir, datafiles, kind, False, "-beta")
+    element_name2, project2, workspace2, _ = open_workspace(cli, tmpdir, datafiles, kind, False, "-beta")
 
     # Assert the workspace dir exists
     assert os.path.exists(workspace2)
@@ -210,7 +212,7 @@ def test_open_force_different_workspace(cli, tmpdir, datafiles, kind):
 @pytest.mark.datafiles(DATA_DIR)
 @pytest.mark.parametrize("kind", repo_kinds)
 def test_close(cli, tmpdir, datafiles, kind):
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, kind, False)
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, kind, False)
 
     # Close the workspace
     result = cli.run(project=project, args=[
@@ -226,7 +228,7 @@ def test_close(cli, tmpdir, datafiles, kind):
 def test_close_external_after_move_project(cli, tmpdir, datafiles):
     workspace_dir = os.path.join(str(tmpdir), "workspace")
     project_path = os.path.join(str(tmpdir), 'initial_project')
-    element_name, _, _ = open_workspace(cli, tmpdir, datafiles, 'git', False, "", workspace_dir, project_path)
+    element_name, _, _, _ = open_workspace(cli, tmpdir, datafiles, 'git', False, "", workspace_dir, project_path)
     assert os.path.exists(workspace_dir)
     moved_dir = os.path.join(str(tmpdir), 'external_project')
     shutil.move(project_path, moved_dir)
@@ -246,8 +248,8 @@ def test_close_external_after_move_project(cli, tmpdir, datafiles):
 def test_close_internal_after_move_project(cli, tmpdir, datafiles):
     initial_dir = os.path.join(str(tmpdir), 'initial_project')
     initial_workspace = os.path.join(initial_dir, 'workspace')
-    element_name, _, _ = open_workspace(cli, tmpdir, datafiles, 'git', False,
-                                        workspace_dir=initial_workspace, project_path=initial_dir)
+    element_name, _, _, _ = open_workspace(cli, tmpdir, datafiles, 'git', False,
+                                           workspace_dir=initial_workspace, project_path=initial_dir)
     moved_dir = os.path.join(str(tmpdir), 'internal_project')
     shutil.move(initial_dir, moved_dir)
     assert os.path.exists(moved_dir)
@@ -265,7 +267,7 @@ def test_close_internal_after_move_project(cli, tmpdir, datafiles):
 
 @pytest.mark.datafiles(DATA_DIR)
 def test_close_removed(cli, tmpdir, datafiles):
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, 'git', False)
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, 'git', False)
 
     # Remove it first, closing the workspace should work
     shutil.rmtree(workspace)
@@ -282,7 +284,7 @@ def test_close_removed(cli, tmpdir, datafiles):
 
 @pytest.mark.datafiles(DATA_DIR)
 def test_close_nonexistant_element(cli, tmpdir, datafiles):
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, 'git', False)
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, 'git', False)
     element_path = os.path.join(datafiles.dirname, datafiles.basename, 'elements', element_name)
 
     # First brutally remove the element.bst file, ensuring that
@@ -304,9 +306,9 @@ def test_close_nonexistant_element(cli, tmpdir, datafiles):
 def test_close_multiple(cli, tmpdir, datafiles):
     tmpdir_alpha = os.path.join(str(tmpdir), 'alpha')
     tmpdir_beta = os.path.join(str(tmpdir), 'beta')
-    alpha, project, workspace_alpha = open_workspace(
+    alpha, project, workspace_alpha, _ = open_workspace(
         cli, tmpdir_alpha, datafiles, 'git', False, suffix='-alpha')
-    beta, project, workspace_beta = open_workspace(
+    beta, project, workspace_beta, _ = open_workspace(
         cli, tmpdir_beta, datafiles, 'git', False, suffix='-beta')
 
     # Close the workspaces
@@ -324,9 +326,9 @@ def test_close_multiple(cli, tmpdir, datafiles):
 def test_close_all(cli, tmpdir, datafiles):
     tmpdir_alpha = os.path.join(str(tmpdir), 'alpha')
     tmpdir_beta = os.path.join(str(tmpdir), 'beta')
-    alpha, project, workspace_alpha = open_workspace(
+    alpha, project, workspace_alpha, _ = open_workspace(
         cli, tmpdir_alpha, datafiles, 'git', False, suffix='-alpha')
-    beta, project, workspace_beta = open_workspace(
+    beta, project, workspace_beta, _ = open_workspace(
         cli, tmpdir_beta, datafiles, 'git', False, suffix='-beta')
 
     # Close the workspaces
@@ -343,7 +345,7 @@ def test_close_all(cli, tmpdir, datafiles):
 @pytest.mark.datafiles(DATA_DIR)
 def test_reset(cli, tmpdir, datafiles):
     # Open the workspace
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, 'git', False)
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, 'git', False)
 
     # Modify workspace
     shutil.rmtree(os.path.join(workspace, 'usr', 'bin'))
@@ -366,9 +368,9 @@ def test_reset_multiple(cli, tmpdir, datafiles):
     # Open the workspaces
     tmpdir_alpha = os.path.join(str(tmpdir), 'alpha')
     tmpdir_beta = os.path.join(str(tmpdir), 'beta')
-    alpha, project, workspace_alpha = open_workspace(
+    alpha, project, workspace_alpha, _ = open_workspace(
         cli, tmpdir_alpha, datafiles, 'git', False, suffix='-alpha')
-    beta, project, workspace_beta = open_workspace(
+    beta, project, workspace_beta, _ = open_workspace(
         cli, tmpdir_beta, datafiles, 'git', False, suffix='-beta')
 
     # Modify workspaces
@@ -392,9 +394,9 @@ def test_reset_all(cli, tmpdir, datafiles):
     # Open the workspaces
     tmpdir_alpha = os.path.join(str(tmpdir), 'alpha')
     tmpdir_beta = os.path.join(str(tmpdir), 'beta')
-    alpha, project, workspace_alpha = open_workspace(
+    alpha, project, workspace_alpha, _ = open_workspace(
         cli, tmpdir_alpha, datafiles, 'git', False, suffix='-alpha')
-    beta, project, workspace_beta = open_workspace(
+    beta, project, workspace_beta, _ = open_workspace(
         cli, tmpdir_beta, datafiles, 'git', False, suffix='-beta')
 
     # Modify workspaces
@@ -415,7 +417,7 @@ def test_reset_all(cli, tmpdir, datafiles):
 
 @pytest.mark.datafiles(DATA_DIR)
 def test_list(cli, tmpdir, datafiles):
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, 'git', False)
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, 'git', False)
 
     # Now list the workspaces
     result = cli.run(project=project, args=[
@@ -437,7 +439,7 @@ def test_list(cli, tmpdir, datafiles):
 @pytest.mark.parametrize("kind", repo_kinds)
 @pytest.mark.parametrize("strict", [("strict"), ("non-strict")])
 def test_build(cli, tmpdir, datafiles, kind, strict):
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, kind, False)
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, kind, False)
     checkout = os.path.join(str(tmpdir), 'checkout')
 
     # Modify workspace
@@ -516,7 +518,7 @@ def test_buildable_no_ref(cli, tmpdir, datafiles):
 @pytest.mark.parametrize("modification", [("addfile"), ("removefile"), ("modifyfile")])
 @pytest.mark.parametrize("strict", [("strict"), ("non-strict")])
 def test_detect_modifications(cli, tmpdir, datafiles, modification, strict):
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, 'git', False)
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, 'git', False)
     checkout = os.path.join(str(tmpdir), 'checkout')
 
     # Configure strict mode
@@ -637,7 +639,8 @@ def test_list_unsupported_workspace(cli, tmpdir, datafiles, workspace_cfg):
             "alpha.bst": {
                 "prepared": False,
                 "path": "/workspaces/bravo",
-                "running_files": {}
+                "running_files": {},
+                "cached_build": False
             }
         }
     }),
@@ -652,7 +655,8 @@ def test_list_unsupported_workspace(cli, tmpdir, datafiles, workspace_cfg):
             "alpha.bst": {
                 "prepared": False,
                 "path": "/workspaces/bravo",
-                "running_files": {}
+                "running_files": {},
+                "cached_build": False
             }
         }
     }),
@@ -670,7 +674,8 @@ def test_list_unsupported_workspace(cli, tmpdir, datafiles, workspace_cfg):
             "alpha.bst": {
                 "prepared": False,
                 "path": "/workspaces/bravo",
-                "running_files": {}
+                "running_files": {},
+                "cached_build": False
             }
         }
     }),
@@ -695,7 +700,8 @@ def test_list_unsupported_workspace(cli, tmpdir, datafiles, workspace_cfg):
                 "last_successful": "some_key",
                 "running_files": {
                     "beta.bst": ["some_file"]
-                }
+                },
+                "cached_build": False
             }
         }
     }),
@@ -715,7 +721,30 @@ def test_list_unsupported_workspace(cli, tmpdir, datafiles, workspace_cfg):
             "alpha.bst": {
                 "prepared": True,
                 "path": "/workspaces/bravo",
-                "running_files": {}
+                "running_files": {},
+                "cached_build": False
+            }
+        }
+    }),
+    # Test loading version 4
+    ({
+        "format-version": 4,
+        "workspaces": {
+            "alpha.bst": {
+                "prepared": False,
+                "path": "/workspaces/bravo",
+                "running_files": {},
+                "cached_build": True
+            }
+        }
+    }, {
+        "format-version": BST_WORKSPACE_FORMAT_VERSION,
+        "workspaces": {
+            "alpha.bst": {
+                "prepared": False,
+                "path": "/workspaces/bravo",
+                "running_files": {},
+                "cached_build": True
             }
         }
     })
@@ -779,7 +808,7 @@ def test_list_supported_workspace(cli, tmpdir, datafiles, workspace_cfg, expecte
 @pytest.mark.datafiles(DATA_DIR)
 @pytest.mark.parametrize("kind", repo_kinds)
 def test_inconsitent_pipeline_message(cli, tmpdir, datafiles, kind):
-    element_name, project, workspace = open_workspace(cli, tmpdir, datafiles, kind, False)
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, kind, False)
 
     shutil.rmtree(workspace)
 
@@ -793,8 +822,8 @@ def test_inconsitent_pipeline_message(cli, tmpdir, datafiles, kind):
 @pytest.mark.parametrize("strict", [("strict"), ("non-strict")])
 def test_cache_key_workspace_in_dependencies(cli, tmpdir, datafiles, strict):
     checkout = os.path.join(str(tmpdir), 'checkout')
-    element_name, project, workspace = open_workspace(cli, os.path.join(str(tmpdir), 'repo-a'),
-                                                      datafiles, 'git', False)
+    element_name, project, workspace, _ = open_workspace(cli, os.path.join(str(tmpdir), 'repo-a'),
+                                                         datafiles, 'git', False)
 
     element_path = os.path.join(project, 'elements')
     back_dep_element_name = 'workspace-test-back-dep.bst'
@@ -869,10 +898,75 @@ def test_multiple_failed_builds(cli, tmpdir, datafiles):
             ]
         }
     }
-    element_name, project, _ = open_workspace(cli, tmpdir, datafiles,
-                                              "git", False, element_attrs=element_config)
+    element_name, project, _, _ = open_workspace(cli, tmpdir, datafiles,
+                                                 "git", False, element_attrs=element_config)
 
     for _ in range(2):
         result = cli.run(project=project, args=["build", element_name])
         assert "BUG" not in result.stderr
         assert cli.get_element_state(project, element_name) != "cached"
+
+
+@pytest.mark.datafiles(DATA_DIR)
+def test_nocache_open_messages(cli, tmpdir, datafiles):
+    # cli default WARN for source dropback possibility when no-cache flag is not passed
+    element_name, project, workspace, result = open_workspace(cli, tmpdir, datafiles, 'git', False, suffix='1')
+    assert "WARNING: Workspace will be opened without the cached buildtree if not cached locally" in result.output
+
+    # cli WARN for source dropback happening when no-cache flag not given, but buildtree not available
+    assert "workspace will be opened with source checkout" in result.stderr
+
+    # cli default WARN for source dropback possibilty not given when no-cache flag is passed
+    tmpdir = os.path.join(str(tmpdir), "2")
+    element_name, project, workspace, result = open_workspace(cli, tmpdir, datafiles, 'git', False, suffix='2',
+                                                              no_cache=True)
+    assert "WARNING: Workspace will be opened without the cached buildtree if not cached locally" not in result.output
+
+
+@pytest.mark.datafiles(DATA_DIR)
+def test_nocache_reset_messages(cli, tmpdir, datafiles):
+    element_name, project, workspace, _ = open_workspace(cli, tmpdir, datafiles, 'git', False, suffix='1')
+
+    # Modify workspace, without building so the artifact is not cached
+    shutil.rmtree(os.path.join(workspace, 'usr', 'bin'))
+    os.makedirs(os.path.join(workspace, 'etc'))
+    with open(os.path.join(workspace, 'etc', 'pony.conf'), 'w') as f:
+        f.write("PONY='pink'")
+
+    # Now reset the open workspace, this should have the
+    # effect of reverting our changes to the original source, as it
+    # was not originally opened with a cached buildtree and as such
+    # should not notify the user
+    result = cli.run(project=project, args=[
+        'workspace', 'reset', element_name
+    ])
+    result.assert_success()
+    assert "original buildtree artifact not available" not in result.output
+    assert os.path.exists(os.path.join(workspace, 'usr', 'bin', 'hello'))
+    assert not os.path.exists(os.path.join(workspace, 'etc', 'pony.conf'))
+
+    # Close the workspace
+    result = cli.run(project=project, args=[
+        'workspace', 'close', '--remove-dir', element_name
+    ])
+    result.assert_success()
+
+    # Build the workspace so we have a cached buildtree artifact for the element
+    assert cli.get_element_state(project, element_name) == 'buildable'
+    result = cli.run(project=project, args=['build', element_name])
+    result.assert_success()
+
+    # Opening the workspace after a build should lead to the cached buildtree being
+    # staged by default
+    result = cli.run(project=project, args=[
+        'workspace', 'open', element_name, workspace
+    ])
+    result.assert_success()
+
+    # Now reset the workspace and ensure that a warning is not given about the artifact
+    # buildtree not being available
+    result = cli.run(project=project, args=[
+        'workspace', 'reset', element_name
+    ])
+    result.assert_success()
+    assert "original buildtree artifact not available" not in result.output