Index: lib/Format/UnwrappedLineParser.cpp
===================================================================
--- lib/Format/UnwrappedLineParser.cpp
+++ lib/Format/UnwrappedLineParser.cpp
@@ -986,6 +986,8 @@
     if (FormatTok->Tok.is(tok::string_literal)) {
       nextToken();
       if (FormatTok->Tok.is(tok::l_brace)) {
+        if (isOnNewLine(*FormatTok))
+          FormatTok->MustBreakBefore = true;
         parseBlock(/*MustBeDeclaration=*/true, /*AddLevel=*/false);
         addUnwrappedLine();
         return;
Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -1595,7 +1595,24 @@
                    Style));
 }
 
-TEST_F(FormatTest, FormatsExternC) { verifyFormat("extern \"C\" {\nint a;"); }
+TEST_F(FormatTest, FormatsExternC) { 
+  verifyFormat("extern \"C\" {\nint a;");
+  verifyFormat("extern \"C\" {};");
+  EXPECT_EQ("extern \"C\" {\n"
+            "int i = 42;\n"
+            "}",
+            format("extern \"C\" {\n"
+                   "int i = 42;\n"
+                   "}"));
+  EXPECT_EQ("extern \"C\"\n" 
+            "{\n"
+            "int i = 42;\n"
+            "}",
+            format("extern \"C\"\n" 
+                   "{\n"
+                   "int i = 42;\n"
+                   "}"));
+}
 
 TEST_F(FormatTest, FormatsInlineASM) {
   verifyFormat("asm(\"xyz\" : \"=a\"(a), \"=d\"(b) : \"a\"(data));");