diff --git a/clang/lib/Tooling/Syntax/Tree.cpp b/clang/lib/Tooling/Syntax/Tree.cpp
--- a/clang/lib/Tooling/Syntax/Tree.cpp
+++ b/clang/lib/Tooling/Syntax/Tree.cpp
@@ -9,6 +9,7 @@
 #include "clang/Basic/TokenKinds.h"
 #include "clang/Tooling/Syntax/Nodes.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Casting.h"
 #include <cassert>
@@ -202,7 +203,7 @@
 }
 
 static void dumpNode(raw_ostream &OS, const syntax::Node *N,
-                     const SourceManager &SM, std::vector<bool> IndentMask) {
+                     const SourceManager &SM, llvm::BitVector IndentMask) {
   auto DumpExtraInfo = [&OS](const syntax::Node *N) {
     if (N->getRole() != syntax::NodeRole::Unknown)
       OS << " " << N->getRole();
@@ -228,8 +229,8 @@
   OS << "\n";
 
   for (const syntax::Node &It : T->getChildren()) {
-    for (bool Filled : IndentMask) {
-      if (Filled)
+    for (unsigned Idx = 0; Idx < IndentMask.size(); ++Idx) {
+      if (IndentMask[Idx])
         OS << "| ";
       else
         OS << "  ";