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
@@ -1808,7 +1808,8 @@
       removeBraces(Line->Children, Result);
       if (!Line->Affected)
         continue;
-      for (FormatToken *Token = Line->First; Token; Token = Token->Next) {
+      for (FormatToken *Token = Line->First; Token && !Token->Finalized;
+           Token = Token->Next) {
         if (!Token->Optional)
           continue;
         assert(Token->isOneOf(tok::l_brace, tok::r_brace));
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -24805,6 +24805,19 @@
                "}",
                Style);
 
+  verifyFormat("// clang-format off\n"
+               "// comment\n"
+               "while (i > 0) { --i; }\n"
+               "// clang-format on\n"
+               "while (j < 0)\n"
+               "  ++j;",
+               "// clang-format off\n"
+               "// comment\n"
+               "while (i > 0) { --i; }\n"
+               "// clang-format on\n"
+               "while (j < 0) { ++j; }",
+               Style);
+
   verifyFormat("if (a)\n"
                "  b; // comment\n"
                "else if (c)\n"