diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -1651,7 +1651,7 @@
   StringRef OldDelimiter = *getRawStringDelimiter(Current.TokenText);
   StringRef NewDelimiter =
       getCanonicalRawStringDelimiter(Style, RawStringStyle.Language);
-  if (NewDelimiter.empty() || OldDelimiter.empty())
+  if (NewDelimiter.empty())
     NewDelimiter = OldDelimiter;
   // The text of a raw string is between the leading 'R"delimiter(' and the
   // trailing 'delimiter)"'.
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -1135,7 +1135,7 @@
               "ParseTestProto",
               "ParsePartialTestProto",
           },
-          /*CanonicalDelimiter=*/"",
+          /*CanonicalDelimiter=*/"pb",
           /*BasedOnStyle=*/"google",
       },
   };