Index: cfe/trunk/lib/Format/BreakableToken.cpp
===================================================================
--- cfe/trunk/lib/Format/BreakableToken.cpp
+++ cfe/trunk/lib/Format/BreakableToken.cpp
@@ -301,12 +301,21 @@
 
 static bool mayReflowContent(StringRef Content) {
   Content = Content.trim(Blanks);
+  // Lines starting with '@' commonly have special meaning.
+  static const SmallVector<StringRef, 4> kSpecialMeaningPrefixes = {
+      "@", "TODO", "FIXME", "XXX"};
+  bool hasSpecialMeaningPrefix = false;
+  for (StringRef Prefix : kSpecialMeaningPrefixes) {
+    if (Content.startswith(Prefix)) {
+      hasSpecialMeaningPrefix = true;
+      break;
+    }
+  }
   // Simple heuristic for what to reflow: content should contain at least two
   // characters and either the first or second character must be
   // non-punctuation.
-  return Content.size() >= 2 &&
-         // Lines starting with '@' commonly have special meaning.
-         !Content.startswith("@") && !Content.endswith("\\") &&
+  return Content.size() >= 2 && !hasSpecialMeaningPrefix &&
+         !Content.endswith("\\") &&
          // Note that this is UTF-8 safe, since if isPunctuation(Content[0]) is
          // true, then the first code point must be 1 byte long.
          (!isPunctuation(Content[0]) || !isPunctuation(Content[1]));
Index: cfe/trunk/unittests/Format/FormatTest.cpp
===================================================================
--- cfe/trunk/unittests/Format/FormatTest.cpp
+++ cfe/trunk/unittests/Format/FormatTest.cpp
@@ -2306,6 +2306,30 @@
             format("// long long long long\n"
                    "// @param arg",
                    getLLVMStyleWithColumns(20)));
+  
+  // Don't reflow lines starting with 'TODO'.
+  EXPECT_EQ("// long long long\n"
+            "// long\n"
+            "// TODO: long",
+            format("// long long long long\n"
+                   "// TODO: long",
+                   getLLVMStyleWithColumns(20)));
+
+  // Don't reflow lines starting with 'FIXME'.
+  EXPECT_EQ("// long long long\n"
+            "// long\n"
+            "// FIXME: long",
+            format("// long long long long\n"
+                   "// FIXME: long",
+                   getLLVMStyleWithColumns(20)));
+
+  // Don't reflow lines starting with 'XXX'.
+  EXPECT_EQ("// long long long\n"
+            "// long\n"
+            "// XXX: long",
+            format("// long long long long\n"
+                   "// XXX: long",
+                   getLLVMStyleWithColumns(20)));
 
   // Reflow lines that have a non-punctuation character among their first 2
   // characters.