diff --git a/lore/settings.py b/lore/settings.py
index bb1d2371..89476e24 100644
--- a/lore/settings.py
+++ b/lore/settings.py
@@ -363,6 +363,6 @@ def get_var(name, default):
     },
     "indexing": {
         "BACKEND": "django.core.cache.backends.locmem.LocMemCache",
-        "TIMEOUT": get_var("CACHE_TIMEOUT", "0"),
+        "TIMEOUT": get_var("CACHE_TIMEOUT", "60"),
     }
 }
diff --git a/search/search_indexes.py b/search/search_indexes.py
index 05af120e..38e0ba66 100644
--- a/search/search_indexes.py
+++ b/search/search_indexes.py
@@ -28,7 +28,7 @@
 cache = caches["indexing"]
 
 
-def get_course_metadata(course_id, force_update=False):
+def get_course_metadata(course_id):
     """
     Caches and returns course metadata.
     Args:
@@ -36,12 +36,9 @@ def get_course_metadata(course_id, force_update=False):
     Returns:
         data (dict): Metadata about course.
     """
-    if force_update is True:
-        cache.clear()
     key = "course_metadata_{0}".format(course_id)
     data = cache.get(key, {})
     if data == {}:
-        log.debug("skm nothing in cache")
         course = Course.objects.select_related("repository").get(id=course_id)
         data["run"] = course.run
         data["course_number"] = course.course_number
@@ -53,7 +50,7 @@ def get_course_metadata(course_id, force_update=False):
     return data
 
 
-def get_vocabs(course_id, resource_id, force_update=False):
+def get_vocabs(course_id, resource_id, solo_update=False):
     """
     Caches and returns taxonomy metadata for a course.
     Args:
@@ -63,24 +60,25 @@ def get_vocabs(course_id, resource_id, force_update=False):
         data (dict): Vocab/term data for course.
     """
     key = "vocab_cache_{0}".format(resource_id)
-    if force_update is True:
-        cache.clear()
     cached = cache.get(key)
-    if cached is not None:
+    if (solo_update is False) and (cached is not None):
         return cached
 
     # Pre-populate the cache with blank values in case there are no
     # terms for that LearningResource. Otherwise, looking up the vocabularies
-    # for that resource will refill the cache for the entire course.
+    # for that resource will refill the cache for the entire course. If there
+    # is already a value, retain it.
     resource_ids = LearningResource.objects.all().values_list('id', flat=True)
     for resource_id in resource_ids:
         rkey = "vocab_cache_{0}".format(resource_id)
-        cache.set(rkey, {})
+        cache.set(rkey, cache.get(rkey, {}))
     value = {}
 
     term_cache = defaultdict(lambda: defaultdict(list))
     rels = LearningResource.terms.related.through.objects.select_related(
         "term").filter(learningresource__course__id=course_id)
+    if solo_update is True:
+        rels = rels.filter(learningresource_id=resource_id)
     for rel in rels.iterator():
         term_cache[rel.learningresource_id][
             rel.term.vocabulary_id].append(rel.term_id)
diff --git a/search/signals.py b/search/signals.py
index 6cd99b84..319a14b7 100644
--- a/search/signals.py
+++ b/search/signals.py
@@ -11,7 +11,7 @@
 from django.db.models.signals import m2m_changed
 from django.dispatch import receiver
 
-from search.search_indexes import LearningResourceIndex
+from search.search_indexes import LearningResourceIndex, get_vocabs
 
 log = logging.getLogger(__name__)
 
@@ -23,4 +23,6 @@ def handle_m2m_save(sender, **kwargs):
     instance = kwargs.pop("instance", None)
     if instance.__class__.__name__ != "LearningResource":
         return
+    # Update cache for the LearningResource if it's already set.
+    get_vocabs(instance.course_id, instance.id, solo_update=True)
     LearningResourceIndex().update_object(instance)
diff --git a/search/tests/test_indexing.py b/search/tests/test_indexing.py
index 54e3ce67..b7116f0d 100644
--- a/search/tests/test_indexing.py
+++ b/search/tests/test_indexing.py
@@ -177,36 +177,33 @@ def test_course_cache(self):
         """
         Test caching -- enabled and disabled -- for course metadata.
         """
-        def three_times(force_update):
+        def three_times():
             """Get course metadata three times."""
             for _ in range(0, 3):
-                get_course_metadata(self.course.id, force_update=force_update)
+                get_course_metadata(self.course.id)
 
         set_cache_timeout(0)
         with self.assertNumQueries(3):
-            three_times(force_update=True)
-        log.debug("skm ran three_times")
+            three_times()
 
         set_cache_timeout(60)
         with self.assertNumQueries(1):
-            three_times(force_update=False)
+            three_times()
 
     def thrice(self):
         """Hit vocabs three times with and without caching."""
-        def three_times(force_update):
+        def three_times():
             """Get vocab data three times."""
             for _ in range(0, 3):
-                get_vocabs(
-                    self.course.id, self.resource.id, force_update=force_update
-                )
+                get_vocabs(self.course.id, self.resource.id)
 
         set_cache_timeout(0)
         with self.assertNumQueries(6):
-            three_times(force_update=True)
+            three_times()
 
         set_cache_timeout(60)
         with self.assertNumQueries(2):
-            three_times(force_update=False)
+            three_times()
 
     def test_term_cache_with_data(self):
         """