diff --git a/lib/database-private.h b/lib/database-private.h
index 431966fb..643b0507 100644
--- a/lib/database-private.h
+++ b/lib/database-private.h
@@ -35,4 +35,17 @@ struct _notmuch_database {
     Xapian::ValueRangeProcessor *value_range_processor;
 };
 
+/* Convert tags from Xapian internal format to notmuch format.
+ *
+ * The function gets a TermIterator as argument and uses that iterator to find
+ * all tag terms in the object. The tags are then converted to a
+ * notmuch_tags_t list and returned. The function needs to allocate memory for
+ * the resulting list and it uses the argument ctx as talloc context.
+ *
+ * The function returns NULL on failure.
+ */
+notmuch_tags_t *
+_notmuch_convert_tags (void *ctx, Xapian::TermIterator &i,
+		       Xapian::TermIterator &end);
+
 #endif
diff --git a/lib/database.cc b/lib/database.cc
index 3fe12dd5..23ddd4ae 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -1029,3 +1029,46 @@ notmuch_database_add_message (notmuch_database_t *notmuch,
 
     return ret;
 }
+
+notmuch_tags_t *
+_notmuch_convert_tags (void *ctx, Xapian::TermIterator &i,
+		       Xapian::TermIterator &end)
+{
+    const char *prefix = _find_prefix ("tag");
+    notmuch_tags_t *tags;
+    std::string tag;
+
+    /* Currently this iteration is written with the assumption that
+     * "tag" has a single-character prefix. */
+    assert (strlen (prefix) == 1);
+
+    tags = _notmuch_tags_create (ctx);
+    if (unlikely (tags == NULL))
+	return NULL;
+
+    i.skip_to (prefix);
+
+    while (i != end) {
+	tag = *i;
+
+	if (tag.empty () || tag[0] != *prefix)
+	    break;
+
+	_notmuch_tags_add_tag (tags, tag.c_str () + 1);
+
+	i++;
+    }
+
+    _notmuch_tags_prepare_iterator (tags);
+
+    return tags;
+}
+
+notmuch_tags_t *
+notmuch_database_get_all_tags (notmuch_database_t *db)
+{
+    Xapian::TermIterator i, end;
+    i = db->xapian_db->allterms_begin();
+    end = db->xapian_db->allterms_end();
+    return _notmuch_convert_tags(db, i, end);
+}
diff --git a/lib/message.cc b/lib/message.cc
index 1e325e23..a410394d 100644
--- a/lib/message.cc
+++ b/lib/message.cc
@@ -463,38 +463,10 @@ notmuch_message_get_date (notmuch_message_t *message)
 notmuch_tags_t *
 notmuch_message_get_tags (notmuch_message_t *message)
 {
-    const char *prefix = _find_prefix ("tag");
     Xapian::TermIterator i, end;
-    notmuch_tags_t *tags;
-    std::string tag;
-
-    /* Currently this iteration is written with the assumption that
-     * "tag" has a single-character prefix. */
-    assert (strlen (prefix) == 1);
-
-    tags = _notmuch_tags_create (message);
-    if (unlikely (tags == NULL))
-	return NULL;
-
-    i = message->doc.termlist_begin ();
-    end = message->doc.termlist_end ();
-
-    i.skip_to (prefix);
-
-    while (i != end) {
-	tag = *i;
-
-	if (tag.empty () || tag[0] != *prefix)
-	    break;
-
-	_notmuch_tags_add_tag (tags, tag.c_str () + 1);
-
-	i++;
-    }
-
-    _notmuch_tags_prepare_iterator (tags);
-
-    return tags;
+    i = message->doc.termlist_begin();
+    end = message->doc.termlist_end();
+    return _notmuch_convert_tags(message, i, end);
 }
 
 void
diff --git a/lib/notmuch.h b/lib/notmuch.h
index 8bba442f..c05e802d 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -280,6 +280,16 @@ notmuch_message_t *
 notmuch_database_find_message (notmuch_database_t *database,
 			       const char *message_id);
 
+/* Return a list of all tags found in the database.
+ *
+ * This function creates a list of all tags found in the database. The
+ * resulting list contains all tags from all messages found in the database.
+ *
+ * On error this function returns NULL.
+ */
+notmuch_tags_t *
+notmuch_database_get_all_tags (notmuch_database_t *db);
+
 /* Create a new query for 'database'.
  *
  * Here, 'database' should be an open database, (see