Index: cfe/trunk/lib/Format/TokenAnnotator.cpp
===================================================================
--- cfe/trunk/lib/Format/TokenAnnotator.cpp
+++ cfe/trunk/lib/Format/TokenAnnotator.cpp
@@ -459,6 +459,8 @@
         updateParameterCount(Left, CurrentToken);
         if (CurrentToken->isOneOf(tok::colon, tok::l_brace, tok::less)) {
           FormatToken *Previous = CurrentToken->getPreviousNonComment();
+          if (Previous->is(TT_JsTypeOptionalQuestion))
+            Previous = Previous->getPreviousNonComment();
           if (((CurrentToken->is(tok::colon) &&
                 (!Contexts.back().ColonIsDictLiteral || !Style.isCpp())) ||
                Style.Language == FormatStyle::LK_Proto ||
@@ -1601,7 +1603,7 @@
       if (Current->is(TT_ConditionalExpr))
         return prec::Conditional;
       if (NextNonComment && Current->is(TT_SelectorName) &&
-          (NextNonComment->is(TT_DictLiteral) ||
+          (NextNonComment->isOneOf(TT_DictLiteral, TT_JsTypeColon) ||
            ((Style.Language == FormatStyle::LK_Proto ||
              Style.Language == FormatStyle::LK_TextProto) &&
             NextNonComment->is(tok::less))))
Index: cfe/trunk/unittests/Format/FormatTestJS.cpp
===================================================================
--- cfe/trunk/unittests/Format/FormatTestJS.cpp
+++ cfe/trunk/unittests/Format/FormatTestJS.cpp
@@ -1561,6 +1561,10 @@
                "  y: number\n"
                "};\n"
                "class C {}");
+  verifyFormat("export type X = {\n"
+               "  a: string,\n"
+               "  b?: string,\n"
+               "};\n");
 }
 
 TEST_F(FormatTestJS, TypeInterfaceLineWrapping) {