diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 1ea9b9e58d4a..a7a48016fe1e 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -9773,8 +9773,7 @@ static void CheckFormatString(Sema &S, const FormatStringLiteral *FExpr,
 
   // Emit a warning if the string literal is truncated and does not contain an
   // embedded null character.
-  if (TypeSize <= StrRef.size() &&
-      StrRef.substr(0, TypeSize).find('\0') == StringRef::npos) {
+  if (TypeSize <= StrRef.size() && !StrRef.substr(0, TypeSize).contains('\0')) {
     CheckFormatHandler::EmitFormatDiagnostic(
         S, inFunctionCall, Args[format_idx],
         S.PDiag(diag::warn_printf_format_string_not_null_terminated),
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index c6c35c6e0cee..5b9568c1ed95 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -3213,13 +3213,13 @@ static void handleCodeSegAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
 bool Sema::checkTargetAttr(SourceLocation LiteralLoc, StringRef AttrStr) {
   enum FirstParam { Unsupported, Duplicate, Unknown };
   enum SecondParam { None, Architecture, Tune };
-  if (AttrStr.find("fpmath=") != StringRef::npos)
+  if (AttrStr.contains("fpmath="))
     return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
            << Unsupported << None << "fpmath=";
 
   // Diagnose use of tune if target doesn't support it.
   if (!Context.getTargetInfo().supportsTargetAttributeTune() &&
-      AttrStr.find("tune=") != StringRef::npos)
+      AttrStr.contains("tune="))
     return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
            << Unsupported << None << "tune=";
 
@@ -7570,7 +7570,7 @@ static void handleOpenCLAccessAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   // C++ for OpenCL 2021 inherits rule from OpenCL C v3.0.
   if (const auto *PDecl = dyn_cast<ParmVarDecl>(D)) {
     const Type *DeclTy = PDecl->getType().getCanonicalType().getTypePtr();
-    if (AL.getAttrName()->getName().find("read_write") != StringRef::npos) {
+    if (AL.getAttrName()->getName().contains("read_write")) {
       bool ReadWriteImagesUnsupported =
           (S.getLangOpts().getOpenCLCompatibleVersion() < 200) ||
           (S.getLangOpts().getOpenCLCompatibleVersion() == 300 &&
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 04f8540fe3b1..2109ff25fe7a 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -12434,8 +12434,7 @@ static void diagnoseXorMisusedAsPow(Sema &S, const ExprResult &XorLHS,
       RHSStrRef.startswith("0x") || RHSStrRef.startswith("0X") ||
       (LHSStrRef.size() > 1 && LHSStrRef.startswith("0")) ||
       (RHSStrRef.size() > 1 && RHSStrRef.startswith("0")) ||
-      LHSStrRef.find('\'') != StringRef::npos ||
-      RHSStrRef.find('\'') != StringRef::npos)
+      LHSStrRef.contains('\'') || RHSStrRef.contains('\''))
     return;
 
   bool SuggestXor =
diff --git a/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp b/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
index d06c87631bfb..61ff5e59f06d 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
@@ -785,9 +785,8 @@ void WalkAST::checkDeprecatedOrUnsafeBufferHandling(const CallExpr *CE,
     // real flow analysis.
     auto FormatString =
         dyn_cast<StringLiteral>(CE->getArg(ArgIndex)->IgnoreParenImpCasts());
-    if (FormatString &&
-        FormatString->getString().find("%s") == StringRef::npos &&
-        FormatString->getString().find("%[") == StringRef::npos)
+    if (FormatString && !FormatString->getString().contains("%s") &&
+        !FormatString->getString().contains("%["))
       BoundsProvided = true;
   }
 
diff --git a/clang/lib/StaticAnalyzer/Checkers/DirectIvarAssignment.cpp b/clang/lib/StaticAnalyzer/Checkers/DirectIvarAssignment.cpp
index df88b71ff063..49486ea796c2 100644
--- a/clang/lib/StaticAnalyzer/Checkers/DirectIvarAssignment.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/DirectIvarAssignment.cpp
@@ -44,8 +44,8 @@ static bool DefaultMethodFilter(const ObjCMethodDecl *M) {
          M->getMethodFamily() == OMF_dealloc ||
          M->getMethodFamily() == OMF_copy ||
          M->getMethodFamily() == OMF_mutableCopy ||
-         M->getSelector().getNameForSlot(0).find("init") != StringRef::npos ||
-         M->getSelector().getNameForSlot(0).find("Init") != StringRef::npos;
+         M->getSelector().getNameForSlot(0).contains("init") ||
+         M->getSelector().getNameForSlot(0).contains("Init");
 }
 
 class DirectIvarAssignment :
diff --git a/clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp
index 20894039c3c0..69e9cbd51c35 100644
--- a/clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp
@@ -789,7 +789,7 @@ bool GenericTaintChecker::isStdin(const Expr *E, CheckerContext &C) {
   // variable named stdin with the proper type.
   if (const auto *D = dyn_cast_or_null<VarDecl>(DeclReg->getDecl())) {
     D = D->getCanonicalDecl();
-    if ((D->getName().find("stdin") != StringRef::npos) && D->isExternC()) {
+    if (D->getName().contains("stdin") && D->isExternC()) {
       const auto *PtrTy = dyn_cast<PointerType>(D->getType().getTypePtr());
       if (PtrTy && PtrTy->getPointeeType().getCanonicalType() ==
                        C.getASTContext().getFILEType().getCanonicalType())
@@ -816,7 +816,7 @@ static bool getPrintfFormatArgumentNum(const CallEvent &Call,
   }
 
   // Or if a function is named setproctitle (this is a heuristic).
-  if (C.getCalleeName(FDecl).find("setproctitle") != StringRef::npos) {
+  if (C.getCalleeName(FDecl).contains("setproctitle")) {
     ArgNum = 0;
     return true;
   }
diff --git a/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
index 5f505f8a0371..f6b5ba098849 100644
--- a/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
@@ -3195,7 +3195,7 @@ bool MallocChecker::mayFreeAnyEscapedMemoryOrIsModeledExplicitly(
       const Expr *ArgE = Call->getArgExpr(0)->IgnoreParenCasts();
       if (const DeclRefExpr *ArgDRE = dyn_cast<DeclRefExpr>(ArgE))
         if (const VarDecl *D = dyn_cast<VarDecl>(ArgDRE->getDecl()))
-          if (D->getCanonicalDecl()->getName().find("std") != StringRef::npos)
+          if (D->getCanonicalDecl()->getName().contains("std"))
             return true;
     }
   }
diff --git a/clang/lib/StaticAnalyzer/Core/CallEvent.cpp b/clang/lib/StaticAnalyzer/Core/CallEvent.cpp
index 5e504ad30b10..1d14e8f2a1ba 100644
--- a/clang/lib/StaticAnalyzer/Core/CallEvent.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CallEvent.cpp
@@ -681,7 +681,7 @@ bool AnyFunctionCall::argumentsMayEscape() const {
 
   // - NSXXInsertXX, for example NSMapInsertIfAbsent, since they can
   //   be deallocated by NSMapRemove.
-  if (FName.startswith("NS") && (FName.find("Insert") != StringRef::npos))
+  if (FName.startswith("NS") && FName.contains("Insert"))
     return true;
 
   // - Many CF containers allow objects to escape through custom
diff --git a/clang/lib/StaticAnalyzer/Core/CheckerContext.cpp b/clang/lib/StaticAnalyzer/Core/CheckerContext.cpp
index 3d64ce453479..df8c834562b6 100644
--- a/clang/lib/StaticAnalyzer/Core/CheckerContext.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CheckerContext.cpp
@@ -55,7 +55,7 @@ bool CheckerContext::isCLibraryFunction(const FunctionDecl *FD,
     if (Name.empty())
       return true;
     StringRef BName = FD->getASTContext().BuiltinInfo.getName(BId);
-    if (BName.find(Name) != StringRef::npos)
+    if (BName.contains(Name))
       return true;
   }
 
@@ -83,11 +83,10 @@ bool CheckerContext::isCLibraryFunction(const FunctionDecl *FD,
   if (FName.equals(Name))
     return true;
 
-  if (FName.startswith("__inline") && (FName.find(Name) != StringRef::npos))
+  if (FName.startswith("__inline") && FName.contains(Name))
     return true;
 
-  if (FName.startswith("__") && FName.endswith("_chk") &&
-      FName.find(Name) != StringRef::npos)
+  if (FName.startswith("__") && FName.endswith("_chk") && FName.contains(Name))
     return true;
 
   return false;
diff --git a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
index 11e4afcfafff..fce348e8f5cf 100644
--- a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
+++ b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -976,7 +976,7 @@ const VarRegion *MemRegionManager::getVarRegion(const VarDecl *D,
     if (Ctx.getSourceManager().isInSystemHeader(D->getLocation())) {
       // Whitelist the system globals which often DO GET modified, assume the
       // rest are immutable.
-      if (D->getName().find("errno") != StringRef::npos)
+      if (D->getName().contains("errno"))
         sReg = getGlobalsRegion(MemRegion::GlobalSystemSpaceRegionKind);
       else
         sReg = getGlobalsRegion(MemRegion::GlobalImmutableSpaceRegionKind);