diff --git a/cms/envs/common.py b/cms/envs/common.py
index fe1dbb0a08..8f070d6ff7 100644
--- a/cms/envs/common.py
+++ b/cms/envs/common.py
@@ -484,6 +484,19 @@ FEATURES = {
     # .. toggle_target_removal_date: None
     # .. toggle_tickets: 'https://openedx.atlassian.net/browse/MST-1348'
     'ENABLE_INTEGRITY_SIGNATURE': False,
+
+    # .. toggle_name: MARK_LIBRARY_CONTENT_BLOCK_COMPLETE_ON_VIEW
+    # .. toggle_implementation: DjangoSetting
+    # .. toggle_default: False
+    # .. toggle_description: If enabled, the Library Content Block is marked as complete when users view it.
+    #   Otherwise (by default), all children of this block must be completed.
+    # .. toggle_use_cases: open_edx
+    # .. toggle_creation_date: 2022-03-22
+    # .. toggle_target_removal_date: None
+    # .. toggle_tickets: https://github.com/edx/edx-platform/pull/28268
+    # .. toggle_warnings: For consistency in user-experience, keep the value in sync with the setting of the same name
+    #   in the LMS and CMS.
+    'MARK_LIBRARY_CONTENT_BLOCK_COMPLETE_ON_VIEW': False,
 }
 
 # .. toggle_name: ENABLE_COPPA_COMPLIANCE
diff --git a/common/lib/xmodule/xmodule/library_content_module.py b/common/lib/xmodule/xmodule/library_content_module.py
index d3bce47bb8..e2b43387a8 100644
--- a/common/lib/xmodule/xmodule/library_content_module.py
+++ b/common/lib/xmodule/xmodule/library_content_module.py
@@ -10,6 +10,8 @@ from copy import copy
 from gettext import ngettext
 
 import bleach
+from django.conf import settings
+from django.utils.functional import classproperty
 from lazy import lazy
 from lxml import etree
 from lxml.etree import XMLSyntaxError
@@ -116,7 +118,18 @@ class LibraryContentBlock(
 
     show_in_read_only_mode = True
 
-    completion_mode = XBlockCompletionMode.AGGREGATOR
+    # noinspection PyMethodParameters
+    @classproperty
+    def completion_mode(cls):  # pylint: disable=no-self-argument
+        """
+        Allow overriding the completion mode with a feature flag.
+
+        This is a property, so it can be dynamically overridden in tests, as it is not evaluated at runtime.
+        """
+        if settings.FEATURES.get('MARK_LIBRARY_CONTENT_BLOCK_COMPLETE_ON_VIEW', False):
+            return XBlockCompletionMode.COMPLETABLE
+
+        return XBlockCompletionMode.AGGREGATOR
 
     display_name = String(
         display_name=_("Display Name"),
diff --git a/lms/envs/common.py b/lms/envs/common.py
index 876dde9d0c..4795c58428 100644
--- a/lms/envs/common.py
+++ b/lms/envs/common.py
@@ -972,6 +972,19 @@ FEATURES = {
     # .. toggle_target_removal_date: None
     # .. toggle_tickets: 'https://openedx.atlassian.net/browse/MICROBA-1758'
     'ENABLE_NEW_BULK_EMAIL_EXPERIENCE': False,
+
+    # .. toggle_name: MARK_LIBRARY_CONTENT_BLOCK_COMPLETE_ON_VIEW
+    # .. toggle_implementation: DjangoSetting
+    # .. toggle_default: False
+    # .. toggle_description: If enabled, the Library Content Block is marked as complete when users view it.
+    #   Otherwise (by default), all children of this block must be completed.
+    # .. toggle_use_cases: open_edx
+    # .. toggle_creation_date: 2022-03-22
+    # .. toggle_target_removal_date: None
+    # .. toggle_tickets: https://github.com/edx/edx-platform/pull/28268
+    # .. toggle_warnings: For consistency in user-experience, keep the value in sync with the setting of the same name
+    #   in the LMS and CMS.
+    'MARK_LIBRARY_CONTENT_BLOCK_COMPLETE_ON_VIEW': False,
 }
 
 # Specifies extra XBlock fields that should available when requested via the Course Blocks API
diff --git a/openedx/core/__pycache__/apidocs.cpython-38.pyc.139860693926064 b/openedx/core/__pycache__/apidocs.cpython-38.pyc.139860693926064
deleted file mode 100644
index e69de29bb2..0000000000
diff --git a/openedx/tests/completion_integration/test_services.py b/openedx/tests/completion_integration/test_services.py
index b24089c86e..0529ec7b71 100644
--- a/openedx/tests/completion_integration/test_services.py
+++ b/openedx/tests/completion_integration/test_services.py
@@ -7,6 +7,8 @@ import ddt
 from completion.models import BlockCompletion
 from completion.services import CompletionService
 from completion.test_utils import CompletionWaffleTestMixin
+from django.conf import settings
+from django.test import override_settings
 from opaque_keys.edx.keys import CourseKey
 from xmodule.library_tools import LibraryToolsService
 from xmodule.modulestore.tests.django_utils import SharedModuleStoreTestCase
@@ -181,6 +183,19 @@ class CompletionServiceTestCase(CompletionWaffleTestMixin, SharedModuleStoreTest
         assert self.completion_service.can_mark_block_complete_on_view(self.html) is True
         assert self.completion_service.can_mark_block_complete_on_view(self.problem) is False
 
+    @override_settings(FEATURES={**settings.FEATURES, 'MARK_LIBRARY_CONTENT_BLOCK_COMPLETE_ON_VIEW': True})
+    def test_can_mark_library_content_complete_on_view(self):
+        library = LibraryFactory.create(modulestore=self.store)
+        lib_vertical = ItemFactory.create(parent=self.sequence, category='vertical', publish_item=False)
+        library_content_block = ItemFactory.create(
+            parent=lib_vertical,
+            category='library_content',
+            max_count=1,
+            source_library_id=str(library.location.library_key),
+            user_id=self.user.id,
+        )
+        self.assertTrue(self.completion_service.can_mark_block_complete_on_view(library_content_block))
+
     def test_vertical_completion_with_library_content(self):
         library = LibraryFactory.create(modulestore=self.store)
         ItemFactory.create(parent=library, category='problem', publish_item=False, user_id=self.user.id)
@@ -202,6 +217,9 @@ class CompletionServiceTestCase(CompletionWaffleTestMixin, SharedModuleStoreTest
             source_library_id=str(library.location.library_key),
             user_id=self.user.id,
         )
+        # Library Content Block needs its children to be completed.
+        self.assertFalse(self.completion_service.can_mark_block_complete_on_view(library_content_block))
+
         library_content_block.refresh_children()
         lib_vertical = self.store.get_item(lib_vertical.location)
         self._bind_course_module(lib_vertical)