diff --git a/IPython/core/completer.py b/IPython/core/completer.py
index c1d43cd..b386945 100644
--- a/IPython/core/completer.py
+++ b/IPython/core/completer.py
@@ -1093,6 +1093,12 @@ class IPCompleter(Completer):
                     return [cast_unicode_py2(r) for r in res if r.lower().startswith(text_low)]
             except TryNext:
                 pass
+            except KeyboardInterrupt:
+                """
+                If custom completer take too long,
+                let keyboard interrupt abort and return nothing.
+                """
+                break
 
         return None