Index: lib/Format/TokenAnnotator.cpp
===================================================================
--- lib/Format/TokenAnnotator.cpp
+++ lib/Format/TokenAnnotator.cpp
@@ -2088,13 +2088,14 @@
         Left.Previous->is(tok::char_constant))
       return true;
     if (Left.is(TT_DictLiteral) && Left.is(tok::l_brace) &&
-        Left.NestingLevel == 0 && Left.Previous &&
+        Line.Level == 0 && Left.Previous &&
         Left.Previous->is(tok::equal) &&
         Line.First->isOneOf(tok::identifier, Keywords.kw_import,
-                            tok::kw_export) &&
+                            tok::kw_export, tok::kw_const) &&
         // kw_var is a pseudo-token that's a tok::identifier, so matches above.
         !Line.First->is(Keywords.kw_var))
-      // Enum style object literal.
+      // Object literals on the top level of a file are treated as "enum-style".
+      // Each key/value pair is put on a separate line, instead of bin-packing.
       return true;
   } else if (Style.Language == FormatStyle::LK_Java) {
     if (Right.is(tok::plus) && Left.is(tok::string_literal) && Right.Next &&
Index: unittests/Format/FormatTestJS.cpp
===================================================================
--- unittests/Format/FormatTestJS.cpp
+++ unittests/Format/FormatTestJS.cpp
@@ -146,6 +146,10 @@
   // Enum style top level assignment.
   verifyFormat("X = {\n  a: 123\n};");
   verifyFormat("X.Y = {\n  a: 123\n};");
+  // But only on the top level, otherwise its a plain object literal assignment.
+  verifyFormat("function x() {\n"
+               "  y = {z: 1};\n"
+               "}");
   verifyFormat("x = foo && {a: 123};");
 
   // Arrow functions in object literals.