diff --git a/clang/lib/Format/BreakableToken.cpp b/clang/lib/Format/BreakableToken.cpp
--- a/clang/lib/Format/BreakableToken.cpp
+++ b/clang/lib/Format/BreakableToken.cpp
@@ -773,10 +773,7 @@
     OriginalPrefix.resize(Lines.size());
     for (size_t i = FirstLineIndex, e = Lines.size(); i < e; ++i) {
       Lines[i] = Lines[i].ltrim(Blanks);
-      // We need to trim the blanks in case this is not the first line in a
-      // multiline comment. Then the indent is included in Lines[i].
-      StringRef IndentPrefix =
-          getLineCommentIndentPrefix(Lines[i].ltrim(Blanks), Style);
+      StringRef IndentPrefix = getLineCommentIndentPrefix(Lines[i], Style);
       assert((TokenText.startswith("//") || TokenText.startswith("#")) &&
              "unsupported line comment prefix, '//' and '#' are supported");
       OriginalPrefix[i] = Prefix[i] = IndentPrefix;