diff --git a/synapse/storage/controllers/state.py b/synapse/storage/controllers/state.py
index 0d480f1014..cbab7a65fe 100644
--- a/synapse/storage/controllers/state.py
+++ b/synapse/storage/controllers/state.py
@@ -232,6 +232,7 @@ class StateStorageController:
         self,
         event_ids: Collection[str],
         state_filter: Optional[StateFilter] = None,
+        await_full_state: Optional[bool] = None,
     ) -> Dict[str, StateMap[str]]:
         """
         Get the state dicts corresponding to a list of events, containing the event_ids
@@ -240,6 +241,9 @@ class StateStorageController:
         Args:
             event_ids: events whose state should be returned
             state_filter: The state filter used to fetch state from the database.
+            await_full_state: if `True`, will block if we do not yet have complete state
+                at these events. Defaults to `True` unless `state_filter` can be
+                completely satisfied with partial state.
 
         Returns:
             A dict from event_id -> (type, state_key) -> event_id
@@ -248,9 +252,13 @@ class StateStorageController:
             RuntimeError if we don't have a state group for one or more of the events
                 (ie they are outliers or unknown)
         """
-        await_full_state = True
-        if state_filter and not state_filter.must_await_full_state(self._is_mine_id):
-            await_full_state = False
+        if await_full_state is None:
+            if state_filter and not state_filter.must_await_full_state(
+                self._is_mine_id
+            ):
+                await_full_state = False
+            else:
+                await_full_state = True
 
         event_to_groups = await self.get_state_group_for_events(
             event_ids, await_full_state=await_full_state
@@ -292,7 +300,10 @@ class StateStorageController:
 
     @trace
     async def get_state_ids_for_event(
-        self, event_id: str, state_filter: Optional[StateFilter] = None
+        self,
+        event_id: str,
+        state_filter: Optional[StateFilter] = None,
+        await_full_state: Optional[bool] = None,
     ) -> StateMap[str]:
         """
         Get the state dict corresponding to a particular event
@@ -300,6 +311,9 @@ class StateStorageController:
         Args:
             event_id: event whose state should be returned
             state_filter: The state filter used to fetch state from the database.
+            await_full_state: if `True`, will block if we do not yet have complete state
+                at the event. Defaults to `True` unless `state_filter` can be completely
+                satisfied with partial state.
 
         Returns:
             A dict from (type, state_key) -> state_event_id
@@ -309,7 +323,9 @@ class StateStorageController:
                 outlier or is unknown)
         """
         state_map = await self.get_state_ids_for_events(
-            [event_id], state_filter or StateFilter.all()
+            [event_id],
+            state_filter or StateFilter.all(),
+            await_full_state=await_full_state,
         )
         return state_map[event_id]