diff --git a/clang/lib/Driver/Distro.cpp b/clang/lib/Driver/Distro.cpp
index cdb5a1725750f..6a11bacb41e5b 100644
--- a/clang/lib/Driver/Distro.cpp
+++ b/clang/lib/Driver/Distro.cpp
@@ -118,11 +118,11 @@ static Distro::DistroType DetectDistro(llvm::vfs::FileSystem &VFS) {
       return Distro::Fedora;
     if (Data.startswith("Red Hat Enterprise Linux") ||
         Data.startswith("CentOS") || Data.startswith("Scientific Linux")) {
-      if (Data.find("release 7") != StringRef::npos)
+      if (Data.contains("release 7"))
         return Distro::RHEL7;
-      else if (Data.find("release 6") != StringRef::npos)
+      else if (Data.contains("release 6"))
         return Distro::RHEL6;
-      else if (Data.find("release 5") != StringRef::npos)
+      else if (Data.contains("release 5"))
         return Distro::RHEL5;
     }
     return Distro::UnknownDistro;
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 6558116bbaebc..bdec63e35f62f 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -436,8 +436,7 @@ static llvm::Triple computeTargetTriple(const Driver &D,
   // GNU/Hurd's triples should have been -hurd-gnu*, but were historically made
   // -gnu* only, and we can not change this, so we have to detect that case as
   // being the Hurd OS.
-  if (TargetTriple.find("-unknown-gnu") != StringRef::npos ||
-      TargetTriple.find("-pc-gnu") != StringRef::npos)
+  if (TargetTriple.contains("-unknown-gnu") || TargetTriple.contains("-pc-gnu"))
     Target.setOSName("hurd");
 
   // Handle Apple-specific options available here.
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index f40adeb063fcb..df205c37f0639 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -583,7 +583,7 @@ std::string ToolChain::GetLinkerPath(bool *LinkerIsLLD,
   // for the linker flavor is brittle. In addition, prepending "ld." or "ld64."
   // to a relative path is surprising. This is more complex due to priorities
   // among -B, COMPILER_PATH and PATH. --ld-path= should be used instead.
-  if (UseLinker.find('/') != StringRef::npos)
+  if (UseLinker.contains('/'))
     getDriver().Diag(diag::warn_drv_fuse_ld_path);
 
   if (llvm::sys::path::is_absolute(UseLinker)) {
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 68b6950364583..e56cd4829759f 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -644,7 +644,7 @@ static void addDebugPrefixMapArg(const Driver &D, const ArgList &Args, ArgString
   for (const Arg *A : Args.filtered(options::OPT_ffile_prefix_map_EQ,
                                     options::OPT_fdebug_prefix_map_EQ)) {
     StringRef Map = A->getValue();
-    if (Map.find('=') == StringRef::npos)
+    if (!Map.contains('='))
       D.Diag(diag::err_drv_invalid_argument_to_option)
           << Map << A->getOption().getName();
     else
@@ -659,7 +659,7 @@ static void addMacroPrefixMapArg(const Driver &D, const ArgList &Args,
   for (const Arg *A : Args.filtered(options::OPT_ffile_prefix_map_EQ,
                                     options::OPT_fmacro_prefix_map_EQ)) {
     StringRef Map = A->getValue();
-    if (Map.find('=') == StringRef::npos)
+    if (!Map.contains('='))
       D.Diag(diag::err_drv_invalid_argument_to_option)
           << Map << A->getOption().getName();
     else
@@ -674,7 +674,7 @@ static void addCoveragePrefixMapArg(const Driver &D, const ArgList &Args,
   for (const Arg *A : Args.filtered(options::OPT_ffile_prefix_map_EQ,
                                     options::OPT_fcoverage_prefix_map_EQ)) {
     StringRef Map = A->getValue();
-    if (Map.find('=') == StringRef::npos)
+    if (!Map.contains('='))
       D.Diag(diag::err_drv_invalid_argument_to_option)
           << Map << A->getOption().getName();
     else
diff --git a/clang/lib/Driver/ToolChains/FreeBSD.cpp b/clang/lib/Driver/ToolChains/FreeBSD.cpp
index 2753876d28d45..7ace08f6e619c 100644
--- a/clang/lib/Driver/ToolChains/FreeBSD.cpp
+++ b/clang/lib/Driver/ToolChains/FreeBSD.cpp
@@ -110,7 +110,7 @@ void freebsd::Assembler::ConstructJob(Compilation &C, const JobAction &JA,
   for (const Arg *A : Args.filtered(options::OPT_ffile_prefix_map_EQ,
                                     options::OPT_fdebug_prefix_map_EQ)) {
     StringRef Map = A->getValue();
-    if (Map.find('=') == StringRef::npos)
+    if (!Map.contains('='))
       D.Diag(diag::err_drv_invalid_argument_to_option)
           << Map << A->getOption().getName();
     else {
diff --git a/clang/lib/Driver/ToolChains/Gnu.cpp b/clang/lib/Driver/ToolChains/Gnu.cpp
index 80e379cb64711..2b5c34b9a63d9 100644
--- a/clang/lib/Driver/ToolChains/Gnu.cpp
+++ b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -930,7 +930,7 @@ void tools::gnutools::Assembler::ConstructJob(Compilation &C,
   for (const Arg *A : Args.filtered(options::OPT_ffile_prefix_map_EQ,
                                     options::OPT_fdebug_prefix_map_EQ)) {
     StringRef Map = A->getValue();
-    if (Map.find('=') == StringRef::npos)
+    if (!Map.contains('='))
       D.Diag(diag::err_drv_invalid_argument_to_option)
           << Map << A->getOption().getName();
     else {
diff --git a/clang/lib/Driver/ToolChains/Linux.cpp b/clang/lib/Driver/ToolChains/Linux.cpp
index a80b8ad4e7ed1..20ed697fecbca 100644
--- a/clang/lib/Driver/ToolChains/Linux.cpp
+++ b/clang/lib/Driver/ToolChains/Linux.cpp
@@ -206,7 +206,7 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
     ExtraOpts.push_back("max-page-size=4096");
   }
 
-  if (GCCInstallation.getParentLibPath().find("opt/rh/") != StringRef::npos)
+  if (GCCInstallation.getParentLibPath().contains("opt/rh/"))
     // With devtoolset on RHEL, we want to add a bin directory that is relative
     // to the detected gcc install, because if we are using devtoolset gcc then
     // we want to use other tools from devtoolset (e.g. ld) instead of the
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 410702d51ed2a..8d33a59cb9839 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -999,7 +999,7 @@ static bool ParseAnalyzerArgs(AnalyzerOptions &Opts, ArgList &Args,
                      diag::err_analyzer_config_no_value) << configVal;
         break;
       }
-      if (val.find('=') != StringRef::npos) {
+      if (val.contains('=')) {
         Diags.Report(SourceLocation(),
                      diag::err_analyzer_config_multiple_values)
           << configVal;
@@ -2061,13 +2061,13 @@ static bool ParseDependencyOutputArgs(DependencyOutputOptions &Opts,
   if (!Args.hasArg(OPT_fno_sanitize_ignorelist)) {
     for (const auto *A : Args.filtered(OPT_fsanitize_ignorelist_EQ)) {
       StringRef Val = A->getValue();
-      if (Val.find('=') == StringRef::npos)
+      if (!Val.contains('='))
         Opts.ExtraDeps.emplace_back(std::string(Val), EDK_SanitizeIgnorelist);
     }
     if (Opts.IncludeSystemHeaders) {
       for (const auto *A : Args.filtered(OPT_fsanitize_system_ignorelist_EQ)) {
         StringRef Val = A->getValue();
-        if (Val.find('=') == StringRef::npos)
+        if (!Val.contains('='))
           Opts.ExtraDeps.emplace_back(std::string(Val), EDK_SanitizeIgnorelist);
       }
     }
@@ -2084,7 +2084,7 @@ static bool ParseDependencyOutputArgs(DependencyOutputOptions &Opts,
   // Only the -fmodule-file=<file> form.
   for (const auto *A : Args.filtered(OPT_fmodule_file)) {
     StringRef Val = A->getValue();
-    if (Val.find('=') == StringRef::npos)
+    if (!Val.contains('='))
       Opts.ExtraDeps.emplace_back(std::string(Val), EDK_ModuleFile);
   }
 
@@ -2728,7 +2728,7 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   // Only the -fmodule-file=<file> form.
   for (const auto *A : Args.filtered(OPT_fmodule_file)) {
     StringRef Val = A->getValue();
-    if (Val.find('=') == StringRef::npos)
+    if (!Val.contains('='))
       Opts.ModuleFiles.push_back(std::string(Val));
   }
 
@@ -3003,7 +3003,7 @@ static bool ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args,
   // Only the -fmodule-file=<name>=<file> form.
   for (const auto *A : Args.filtered(OPT_fmodule_file)) {
     StringRef Val = A->getValue();
-    if (Val.find('=') != StringRef::npos){
+    if (Val.contains('=')) {
       auto Split = Val.split('=');
       Opts.PrebuiltModuleFiles.insert(
           {std::string(Split.first), std::string(Split.second)});
diff --git a/clang/lib/Frontend/LayoutOverrideSource.cpp b/clang/lib/Frontend/LayoutOverrideSource.cpp
index c735c6c42cb32..0d288db0632fd 100644
--- a/clang/lib/Frontend/LayoutOverrideSource.cpp
+++ b/clang/lib/Frontend/LayoutOverrideSource.cpp
@@ -43,7 +43,7 @@ LayoutOverrideSource::LayoutOverrideSource(StringRef Filename) {
     StringRef LineStr(Line);
 
     // Determine whether the following line will start a
-    if (LineStr.find("*** Dumping AST Record Layout") != StringRef::npos)  {
+    if (LineStr.contains("*** Dumping AST Record Layout")) {
       // Flush the last type/layout, if there is one.
       if (!CurrentType.empty())
         Layouts[CurrentType] = CurrentLayout;
diff --git a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
index 0503ae46a15fb..2759625ae254e 100644
--- a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
+++ b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
@@ -99,9 +99,7 @@ class StandardDirective : public Directive {
     return true;
   }
 
-  bool match(StringRef S) override {
-    return S.find(Text) != StringRef::npos;
-  }
+  bool match(StringRef S) override { return S.contains(Text); }
 };
 
 /// RegexDirective - Directive with regular-expression matching.