diff --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
index 62e3e5ad0a52be..5cf5e9463b451c 100644
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -1244,7 +1244,7 @@ static bool InstrBreaksNonThrowing(Instruction &I, const SCCNodeSet &SCCNodes) {
       // I is a may-throw call to a function inside our SCC. This doesn't
       // invalidate our current working assumption that the SCC is no-throw; we
       // just have to scan that other function.
-      if (SCCNodes.count(Callee) > 0)
+      if (SCCNodes.contains(Callee))
         return false;
     }
   }
@@ -1264,7 +1264,7 @@ static bool InstrBreaksNoFree(Instruction &I, const SCCNodeSet &SCCNodes) {
   if (Callee->doesNotFreeMemory())
     return false;
 
-  if (SCCNodes.count(Callee) > 0)
+  if (SCCNodes.contains(Callee))
     return false;
 
   return true;
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 8750e83623e6a1..a3d86e26fe2396 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -2523,7 +2523,7 @@ Instruction *InstCombinerImpl::optimizeBitCastFromPhi(CastInst &CI,
         if (BCI == &CI)
           RetVal = I;
       } else if (auto *PHI = dyn_cast<PHINode>(V)) {
-        assert(OldPhiNodes.count(PHI) > 0);
+        assert(OldPhiNodes.contains(PHI));
         (void) PHI;
       } else {
         llvm_unreachable("all uses should be handled");
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 08877797c53abc..888166f1f53d75 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -502,7 +502,7 @@ static bool canRewriteGEPAsOffset(Value *Start, Value *Base,
 
       Value *V = WorkList.back();
 
-      if (Explored.count(V) != 0) {
+      if (Explored.contains(V)) {
         WorkList.pop_back();
         continue;
       }
diff --git a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
index d9416072793a82..927c34180db934 100644
--- a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
+++ b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
@@ -731,7 +731,7 @@ static Instruction* getBranchInsertPoint(RegInfo &RI) {
     }
   }
   for (Instruction &I : *EntryBB) {
-    if (EntryBlockSelectSet.count(&I) > 0) {
+    if (EntryBlockSelectSet.contains(&I)) {
       assert(&I == HoistPoint &&
              "HoistPoint must be the first one in Selects");
       break;
@@ -1304,17 +1304,17 @@ void CHR::classifyBiasedScopes(CHRScope *Scope, CHRScope *OutermostScope) {
   for (RegInfo &RI : Scope->RegInfos) {
     if (RI.HasBranch) {
       Region *R = RI.R;
-      if (TrueBiasedRegionsGlobal.count(R) > 0)
+      if (TrueBiasedRegionsGlobal.contains(R))
         OutermostScope->TrueBiasedRegions.insert(R);
-      else if (FalseBiasedRegionsGlobal.count(R) > 0)
+      else if (FalseBiasedRegionsGlobal.contains(R))
         OutermostScope->FalseBiasedRegions.insert(R);
       else
         llvm_unreachable("Must be biased");
     }
     for (SelectInst *SI : RI.Selects) {
-      if (TrueBiasedSelectsGlobal.count(SI) > 0)
+      if (TrueBiasedSelectsGlobal.contains(SI))
         OutermostScope->TrueBiasedSelects.insert(SI);
-      else if (FalseBiasedSelectsGlobal.count(SI) > 0)
+      else if (FalseBiasedSelectsGlobal.contains(SI))
         OutermostScope->FalseBiasedSelects.insert(SI);
       else
         llvm_unreachable("Must be biased");
@@ -1397,8 +1397,8 @@ void CHR::setCHRRegions(CHRScope *Scope, CHRScope *OutermostScope) {
     DenseSet<Instruction *> HoistStops;
     bool IsHoisted = false;
     if (RI.HasBranch) {
-      assert((OutermostScope->TrueBiasedRegions.count(R) > 0 ||
-              OutermostScope->FalseBiasedRegions.count(R) > 0) &&
+      assert((OutermostScope->TrueBiasedRegions.contains(R) ||
+              OutermostScope->FalseBiasedRegions.contains(R)) &&
              "Must be truthy or falsy");
       auto *BI = cast<BranchInst>(R->getEntry()->getTerminator());
       // Note checkHoistValue fills in HoistStops.
@@ -1410,8 +1410,8 @@ void CHR::setCHRRegions(CHRScope *Scope, CHRScope *OutermostScope) {
       IsHoisted = true;
     }
     for (SelectInst *SI : RI.Selects) {
-      assert((OutermostScope->TrueBiasedSelects.count(SI) > 0 ||
-              OutermostScope->FalseBiasedSelects.count(SI) > 0) &&
+      assert((OutermostScope->TrueBiasedSelects.contains(SI) ||
+              OutermostScope->FalseBiasedSelects.contains(SI)) &&
              "Must be true or false biased");
       // Note checkHoistValue fills in HoistStops.
       DenseMap<Instruction *, bool> Visited;
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index e8de6f425db6e8..96aef90c1c1a35 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -1757,7 +1757,7 @@ bool JumpThreadingPass::processThreadableEdges(Value *Cond, BasicBlock *BB,
     // and we still want to process.
     erase_if(PredToDestList,
              [&](const std::pair<BasicBlock *, BasicBlock *> &PredToDest) {
-               return LoopHeaders.count(PredToDest.second) != 0;
+               return LoopHeaders.contains(PredToDest.second);
              });
 
     if (PredToDestList.empty())
diff --git a/llvm/lib/Transforms/Scalar/LoopRerollPass.cpp b/llvm/lib/Transforms/Scalar/LoopRerollPass.cpp
index 2a04137e5d2f52..b3bae47e96de24 100644
--- a/llvm/lib/Transforms/Scalar/LoopRerollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopRerollPass.cpp
@@ -1096,7 +1096,7 @@ LoopReroll::DAGRootTracker::nextInstr(int Val, UsesTy &In,
                                       UsesTy::iterator *StartI) {
   UsesTy::iterator I = StartI ? *StartI : In.begin();
   while (I != In.end() && (I->second.test(Val) == 0 ||
-                           Exclude.count(I->first) != 0))
+                           Exclude.contains(I->first)))
     ++I;
   return I;
 }
diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index d09f1ee22a752c..ef25963a997ad9 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -1371,7 +1371,7 @@ PreservedAnalyses LoopFullUnrollPass::run(Loop &L, LoopAnalysisManager &AM,
     }
 
     // Otherwise erase the loop from the list if it was in the old loops.
-    return OldLoops.count(SibLoop) != 0;
+    return OldLoops.contains(SibLoop);
   });
   Updater.addSiblingLoops(SibLoops);
 
diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index c8e5fdb458ffb9..8c06e29341adef 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -7586,7 +7586,7 @@ bool SLPVectorizerPass::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
       continue;
     // We may go through BB multiple times so skip the one we have checked.
     if (!VisitedInstrs.insert(&*it).second) {
-      if (it->use_empty() && KeyNodes.count(&*it) > 0 &&
+      if (it->use_empty() && KeyNodes.contains(&*it) &&
           vectorizeSimpleInstructions(PostProcessInstructions, BB, R)) {
         // We would like to start over since some instructions are deleted
         // and the iterator may become invalid value.