Index: lib/Format/TokenAnnotator.cpp
===================================================================
--- lib/Format/TokenAnnotator.cpp
+++ lib/Format/TokenAnnotator.cpp
@@ -2270,8 +2270,12 @@
     if (Right.is(tok::l_paren) && Line.MustBeDeclaration &&
         Left.Tok.getIdentifierInfo())
       return false;
-    if (Left.isOneOf(Keywords.kw_let, Keywords.kw_var, Keywords.kw_in,
-                     Keywords.kw_of, tok::kw_const) &&
+    if ((Left.isOneOf(Keywords.kw_let, Keywords.kw_var, Keywords.kw_in,
+                      tok::kw_const) ||
+         // "of" is only a keyword if it appears after another identifier
+         // (e.g. as "const x of y" in a for loop).
+         (Left.is(Keywords.kw_of) && Left.Previous &&
+          Left.Previous->Tok.getIdentifierInfo())) &&
         (!Left.Previous || !Left.Previous->is(tok::period)))
       return true;
     if (Left.isOneOf(tok::kw_for, Keywords.kw_as) && Left.Previous &&
Index: unittests/Format/FormatTestJS.cpp
===================================================================
--- unittests/Format/FormatTestJS.cpp
+++ unittests/Format/FormatTestJS.cpp
@@ -132,6 +132,8 @@
   verifyFormat("x.interface = 1;");
   verifyFormat("x.for = 1;");
   verifyFormat("x.of() = 1;");
+  verifyFormat("of(null);");
+  verifyFormat("import {of} from 'x';");
   verifyFormat("x.in() = 1;");
   verifyFormat("x.let() = 1;");
   verifyFormat("x.var() = 1;");