diff --git a/llvm/include/llvm/Analysis/BlockFrequencyInfoImpl.h b/llvm/include/llvm/Analysis/BlockFrequencyInfoImpl.h
--- a/llvm/include/llvm/Analysis/BlockFrequencyInfoImpl.h
+++ b/llvm/include/llvm/Analysis/BlockFrequencyInfoImpl.h
@@ -14,6 +14,7 @@
 #ifndef LLVM_ANALYSIS_BLOCKFREQUENCYINFOIMPL_H
 #define LLVM_ANALYSIS_BLOCKFREQUENCYINFOIMPL_H
 
+#include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/GraphTraits.h"
@@ -1451,7 +1452,7 @@
   // frequencies need to be updated based on the incoming edges.
   // The set is dynamic and changes after every update. Initially all blocks
   // with a positive frequency are active
-  auto IsActive = std::vector<bool>(Freq.size(), false);
+  auto IsActive = BitVector(Freq.size(), false);
   std::queue<size_t> ActiveSet;
   for (size_t I = 0; I < Freq.size(); I++) {
     if (Freq[I] > 0) {
diff --git a/llvm/lib/Analysis/DevelopmentModeInlineAdvisor.cpp b/llvm/lib/Analysis/DevelopmentModeInlineAdvisor.cpp
--- a/llvm/lib/Analysis/DevelopmentModeInlineAdvisor.cpp
+++ b/llvm/lib/Analysis/DevelopmentModeInlineAdvisor.cpp
@@ -15,6 +15,7 @@
 #if defined(LLVM_HAVE_TF_API)
 
 #include "llvm/Analysis/CallGraph.h"
+#include "llvm/ADT/BitVector.h"
 #include "llvm/Analysis/InlineSizeEstimatorAnalysis.h"
 #include "llvm/Analysis/MLInlineAdvisor.h"
 #include "llvm/Analysis/ModelUnderTrainingRunner.h"
@@ -112,7 +113,7 @@
   StringRef LogFileName;
   const ModelUnderTrainingRunner *const MUTR;
   std::unique_ptr<Logger> L;
-  std::vector<bool> Effects;
+  BitVector Effects;
   /// There's at least one output. We'll set this to a different value if MUTR
   /// is avaliable.
   size_t OutputCount = 1;
diff --git a/llvm/lib/Transforms/Utils/SampleProfileInference.cpp b/llvm/lib/Transforms/Utils/SampleProfileInference.cpp
--- a/llvm/lib/Transforms/Utils/SampleProfileInference.cpp
+++ b/llvm/lib/Transforms/Utils/SampleProfileInference.cpp
@@ -13,6 +13,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/ADT/BitVector.h"
 #include "llvm/Transforms/Utils/SampleProfileInference.h"
 #include "llvm/Support/Debug.h"
 #include <queue>
@@ -309,7 +310,7 @@
 private:
   void joinIsolatedComponents() {
     // Find blocks that are reachable from the source
-    auto Visited = std::vector<bool>(NumBlocks(), false);
+    auto Visited = BitVector(NumBlocks(), false);
     findReachable(Func.Entry, Visited);
 
     // Iterate over all non-reachable blocks and adjust their weights
@@ -334,7 +335,7 @@
 
   /// Run BFS from a given block along the jumps with a positive flow and mark
   /// all reachable blocks.
-  void findReachable(uint64_t Src, std::vector<bool> &Visited) {
+  void findReachable(uint64_t Src, BitVector &Visited) {
     if (Visited[Src])
       return;
     std::queue<uint64_t> Queue;
@@ -488,7 +489,7 @@
                            std::vector<FlowBlock *> &UnknownSuccs) {
     // Run BFS from SrcBlock and make sure all paths are going through unknown
     // blocks and end at a non-unknown DstBlock
-    auto Visited = std::vector<bool>(NumBlocks(), false);
+    auto Visited = BitVector(NumBlocks(), false);
     std::queue<uint64_t> Queue;
     DstBlock = nullptr;
 
@@ -800,7 +801,7 @@
 
   // Run BFS from the source along edges with positive flow
   std::queue<uint64_t> Queue;
-  auto Visited = std::vector<bool>(NumBlocks, false);
+  auto Visited = BitVector(NumBlocks, false);
   Queue.push(Func.Entry);
   Visited[Func.Entry] = true;
   while (!Queue.empty()) {
diff --git a/llvm/tools/llvm-lto/llvm-lto.cpp b/llvm/tools/llvm-lto/llvm-lto.cpp
--- a/llvm/tools/llvm-lto/llvm-lto.cpp
+++ b/llvm/tools/llvm-lto/llvm-lto.cpp
@@ -267,7 +267,7 @@
 namespace {
 
 struct ModuleInfo {
-  std::vector<bool> CanBeHidden;
+  BitVector CanBeHidden;
 };
 
 } // end anonymous namespace
diff --git a/llvm/tools/llvm-rc/ResourceScriptParser.cpp b/llvm/tools/llvm-rc/ResourceScriptParser.cpp
--- a/llvm/tools/llvm-rc/ResourceScriptParser.cpp
+++ b/llvm/tools/llvm-rc/ResourceScriptParser.cpp
@@ -741,7 +741,7 @@
     // possibly preceded by a comma. Unfortunately, the tool behavior depends
     // on them existing or not, so we need to memorize where we found them.
     std::vector<IntOrString> Values;
-    std::vector<bool> PrecedingCommas;
+    BitVector PrecedingCommas;
     RETURN_IF_ERROR(consumeType(Kind::Comma));
     while (!isNextTokenKind(Kind::Identifier) &&
            !isNextTokenKind(Kind::BlockEnd)) {
diff --git a/llvm/tools/llvm-rc/ResourceScriptStmt.h b/llvm/tools/llvm-rc/ResourceScriptStmt.h
--- a/llvm/tools/llvm-rc/ResourceScriptStmt.h
+++ b/llvm/tools/llvm-rc/ResourceScriptStmt.h
@@ -16,6 +16,7 @@
 #include "ResourceScriptToken.h"
 #include "ResourceVisitor.h"
 
+#include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/StringSet.h"
 
 namespace llvm {
@@ -768,10 +769,10 @@
 public:
   StringRef Key;
   std::vector<IntOrString> Values;
-  std::vector<bool> HasPrecedingComma;
+  BitVector HasPrecedingComma;
 
   VersionInfoValue(StringRef InfoKey, std::vector<IntOrString> &&Vals,
-                   std::vector<bool> &&CommasBeforeVals)
+                   BitVector &&CommasBeforeVals)
       : Key(InfoKey), Values(std::move(Vals)),
         HasPrecedingComma(std::move(CommasBeforeVals)) {}
   raw_ostream &log(raw_ostream &) const override;
diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -17,6 +17,7 @@
 #include "StackMapPrinter.h"
 #include "llvm-readobj.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/MapVector.h"
@@ -3905,7 +3906,7 @@
   for (uint32_t Buc = 0; Buc < SysVHash.nbucket; Buc++) {
     if (Buckets[Buc] == ELF::STN_UNDEF)
       continue;
-    std::vector<bool> Visited(SysVHash.nchain);
+    BitVector Visited(SysVHash.nchain);
     for (uint32_t Ch = Buckets[Buc]; Ch < SysVHash.nchain; Ch = Chains[Ch]) {
       if (Ch == ELF::STN_UNDEF)
         break;
@@ -4653,7 +4654,7 @@
   // Go over all buckets and and note chain lengths of each bucket (total
   // unique chain lengths).
   for (size_t B = 0; B < NBucket; B++) {
-    std::vector<bool> Visited(NChain);
+    BitVector Visited(NChain);
     for (size_t C = Buckets[B]; C < NChain; C = Chains[C]) {
       if (C == ELF::STN_UNDEF)
         break;
diff --git a/llvm/unittests/Analysis/AssumeBundleQueriesTest.cpp b/llvm/unittests/Analysis/AssumeBundleQueriesTest.cpp
--- a/llvm/unittests/Analysis/AssumeBundleQueriesTest.cpp
+++ b/llvm/unittests/Analysis/AssumeBundleQueriesTest.cpp
@@ -433,7 +433,7 @@
   Function *FnAssume = Intrinsic::getDeclaration(Mod.get(), Intrinsic::assume);
 
   std::vector<Argument *> ShuffledArgs;
-  std::vector<bool> HasArg;
+  BitVector HasArg;
   for (auto &Arg : F->args()) {
     ShuffledArgs.push_back(&Arg);
     HasArg.push_back(false);
diff --git a/llvm/utils/TableGen/CodeGenInstruction.h b/llvm/utils/TableGen/CodeGenInstruction.h
--- a/llvm/utils/TableGen/CodeGenInstruction.h
+++ b/llvm/utils/TableGen/CodeGenInstruction.h
@@ -13,6 +13,7 @@
 #ifndef LLVM_UTILS_TABLEGEN_CODEGENINSTRUCTION_H
 #define LLVM_UTILS_TABLEGEN_CODEGENINSTRUCTION_H
 
+#include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/MachineValueType.h"
 #include "llvm/Support/SMLoc.h"
@@ -106,7 +107,7 @@
       /// DoNotEncode - Bools are set to true in this vector for each operand in
       /// the DisableEncoding list.  These should not be emitted by the code
       /// emitter.
-      std::vector<bool> DoNotEncode;
+      BitVector DoNotEncode;
 
       /// MIOperandInfo - Default MI operand type. Note an operand may be made
       /// up of multiple MI operands.
diff --git a/llvm/utils/TableGen/GlobalISel/GIMatchTree.h b/llvm/utils/TableGen/GlobalISel/GIMatchTree.h
--- a/llvm/utils/TableGen/GlobalISel/GIMatchTree.h
+++ b/llvm/utils/TableGen/GlobalISel/GIMatchTree.h
@@ -588,7 +588,7 @@
   unsigned OpIdx;
   std::vector<BitVector> TraversedEdges;
   DenseMap<unsigned, unsigned> ResultToPartition;
-  std::vector<bool> PartitionToResult;
+  BitVector PartitionToResult;
 
   void addToPartition(bool Result, unsigned LeafIdx);