Index: lib/Format/UnwrappedLineParser.cpp
===================================================================
--- lib/Format/UnwrappedLineParser.cpp
+++ lib/Format/UnwrappedLineParser.cpp
@@ -303,6 +303,18 @@
   else
     parseLevel(/*HasOpeningBrace=*/false);
   // Make sure to format the remaining tokens.
+  //
+  // LK_TextProto is special since its top-level is parsed as the body of a
+  // braced list, which does not necessarily have natural line separators such
+  // as a semicolon. Comments after the last entry that have been determined to
+  // not belong to that line, as in:
+  //   key: value
+  //   // endfile comment
+  // do not have a chance to be put on a line of their own until this point.
+  // Here we add this newline before end-of-file comments.
+  if (Style.Language == FormatStyle::LK_TextProto &&
+      !CommentsBeforeNextToken.empty())
+    addUnwrappedLine();
   flushComments(true);
   addUnwrappedLine();
 }
Index: unittests/Format/FormatTestTextProto.cpp
===================================================================
--- unittests/Format/FormatTestTextProto.cpp
+++ unittests/Format/FormatTestTextProto.cpp
@@ -700,5 +700,22 @@
       "}");
 }
 
+TEST_F(FormatTestTextProto, FormatsCommentsAtEndOfFile) {
+  verifyFormat("key: value\n"
+               "# endfile comment");
+  verifyFormat("key: value\n"
+               "// endfile comment");
+  verifyFormat("key: value\n"
+               "// endfile comment 1\n"
+               "// endfile comment 2");
+  verifyFormat("submessage { key: value }\n"
+               "# endfile comment");
+  verifyFormat("submessage <\n"
+               "  key: value\n"
+               "  item {}\n"
+               ">\n"
+               "# endfile comment");
+}
+
 } // end namespace tooling
 } // end namespace clang