diff --git a/llvm/include/llvm/ADT/StringRef.h b/llvm/include/llvm/ADT/StringRef.h
--- a/llvm/include/llvm/ADT/StringRef.h
+++ b/llvm/include/llvm/ADT/StringRef.h
@@ -630,7 +630,7 @@
     /// Returns true if this StringRef has the given prefix, ignoring case,
     /// and removes that prefix.
     bool consume_front_insensitive(StringRef Prefix) {
-      if (!startswith_insensitive(Prefix))
+      if (!starts_with_insensitive(Prefix))
         return false;
 
       *this = substr(Prefix.size());
@@ -650,7 +650,7 @@
     /// Returns true if this StringRef has the given suffix, ignoring case,
     /// and removes that suffix.
     bool consume_back_insensitive(StringRef Suffix) {
-      if (!endswith_insensitive(Suffix))
+      if (!ends_with_insensitive(Suffix))
         return false;
 
       *this = substr(0, size() - Suffix.size());
diff --git a/llvm/include/llvm/ADT/StringSwitch.h b/llvm/include/llvm/ADT/StringSwitch.h
--- a/llvm/include/llvm/ADT/StringSwitch.h
+++ b/llvm/include/llvm/ADT/StringSwitch.h
@@ -147,14 +147,14 @@
   }
 
   StringSwitch &EndsWithLower(StringLiteral S, T Value) {
-    if (!Result && Str.endswith_insensitive(S))
+    if (!Result && Str.ends_with_insensitive(S))
       Result = Value;
 
     return *this;
   }
 
   StringSwitch &StartsWithLower(StringLiteral S, T Value) {
-    if (!Result && Str.startswith_insensitive(S))
+    if (!Result && Str.starts_with_insensitive(S))
       Result = std::move(Value);
 
     return *this;
diff --git a/llvm/include/llvm/Support/FormatProviders.h b/llvm/include/llvm/Support/FormatProviders.h
--- a/llvm/include/llvm/Support/FormatProviders.h
+++ b/llvm/include/llvm/Support/FormatProviders.h
@@ -76,7 +76,7 @@
   }
 
   static bool consumeHexStyle(StringRef &Str, HexPrintStyle &Style) {
-    if (!Str.startswith_insensitive("x"))
+    if (!Str.starts_with_insensitive("x"))
       return false;
 
     if (Str.consume_front("x-"))
diff --git a/llvm/lib/DebugInfo/PDB/Native/InputFile.cpp b/llvm/lib/DebugInfo/PDB/Native/InputFile.cpp
--- a/llvm/lib/DebugInfo/PDB/Native/InputFile.cpp
+++ b/llvm/lib/DebugInfo/PDB/Native/InputFile.cpp
@@ -562,13 +562,13 @@
   StringRef Name = Group.name();
   if (Name.startswith("Import:"))
     return false;
-  if (Name.endswith_insensitive(".dll"))
+  if (Name.ends_with_insensitive(".dll"))
     return false;
   if (Name.equals_insensitive("* linker *"))
     return false;
-  if (Name.startswith_insensitive("f:\\binaries\\Intermediate\\vctools"))
+  if (Name.starts_with_insensitive("f:\\binaries\\Intermediate\\vctools"))
     return false;
-  if (Name.startswith_insensitive("f:\\dd\\vctools\\crt"))
+  if (Name.starts_with_insensitive("f:\\dd\\vctools\\crt"))
     return false;
   return true;
 }
diff --git a/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp b/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
--- a/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
@@ -1103,7 +1103,7 @@
 public:
   LoadAndLinkDynLibrary(LLJIT &J) : J(J) {}
   Error operator()(JITDylib &JD, StringRef DLLName) {
-    if (!DLLName.endswith_insensitive(".dll"))
+    if (!DLLName.ends_with_insensitive(".dll"))
       return make_error<StringError>("DLLName not ending with .dll",
                                      inconvertibleErrorCode());
     auto DLLNameStr = DLLName.str(); // Guarantees null-termination.
diff --git a/llvm/lib/Option/OptTable.cpp b/llvm/lib/Option/OptTable.cpp
--- a/llvm/lib/Option/OptTable.cpp
+++ b/llvm/lib/Option/OptTable.cpp
@@ -163,7 +163,7 @@
   for (auto Prefix : I->Prefixes) {
     if (Str.startswith(Prefix)) {
       StringRef Rest = Str.substr(Prefix.size());
-      bool Matched = IgnoreCase ? Rest.startswith_insensitive(I->Name)
+      bool Matched = IgnoreCase ? Rest.starts_with_insensitive(I->Name)
                                 : Rest.startswith(I->Name);
       if (Matched)
         return Prefix.size() + StringRef(I->Name).size();
diff --git a/llvm/lib/Support/StringRef.cpp b/llvm/lib/Support/StringRef.cpp
--- a/llvm/lib/Support/StringRef.cpp
+++ b/llvm/lib/Support/StringRef.cpp
@@ -191,7 +191,7 @@
 size_t StringRef::find_insensitive(StringRef Str, size_t From) const {
   StringRef This = substr(From);
   while (This.size() >= Str.size()) {
-    if (This.startswith_insensitive(Str))
+    if (This.starts_with_insensitive(Str))
       return From;
     This = This.drop_front();
     ++From;
diff --git a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
--- a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
+++ b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
@@ -3486,7 +3486,7 @@
 
   StringRef Name = Tok.getString();
 
-  if (Name.equals_insensitive("za") || Name.startswith_insensitive("za.")) {
+  if (Name.equals_insensitive("za") || Name.starts_with_insensitive("za.")) {
     Lex(); // eat "za[.(b|h|s|d)]"
     unsigned ElementWidth = 0;
     auto DotPosition = Name.find('.');
@@ -3868,7 +3868,7 @@
   SMLoc S = Tok.getLoc();
 
   if (Mnemonic == "tlbip") {
-    bool HasnXSQualifier = Op.endswith_insensitive("nXS");
+    bool HasnXSQualifier = Op.ends_with_insensitive("nXS");
     if (HasnXSQualifier) {
       Op = Op.drop_back(3);
     }
@@ -4463,7 +4463,7 @@
     if (RegTok.isNot(AsmToken::Identifier) ||
         ParseRes == MatchOperand_ParseFail ||
         (ParseRes == MatchOperand_NoMatch && NoMatchIsError &&
-         !RegTok.getString().startswith_insensitive("za"))) {
+         !RegTok.getString().starts_with_insensitive("za"))) {
       Error(Loc, "vector register expected");
       return MatchOperand_ParseFail;
     }
@@ -6910,7 +6910,7 @@
   for (auto Name : RequestedExtensions) {
     bool EnableFeature = true;
 
-    if (Name.startswith_insensitive("no")) {
+    if (Name.starts_with_insensitive("no")) {
       EnableFeature = false;
       Name = Name.substr(2);
     }
@@ -6944,7 +6944,7 @@
     return true;
 
   bool EnableFeature = true;
-  if (Name.startswith_insensitive("no")) {
+  if (Name.starts_with_insensitive("no")) {
     EnableFeature = false;
     Name = Name.substr(2);
   }
@@ -7006,7 +7006,7 @@
 
     bool EnableFeature = true;
 
-    if (Name.startswith_insensitive("no")) {
+    if (Name.starts_with_insensitive("no")) {
       EnableFeature = false;
       Name = Name.substr(2);
     }
diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -12775,7 +12775,7 @@
       {ARM::AEK_XSCALE, {}, {}},
   };
   bool EnableFeature = true;
-  if (Name.startswith_insensitive("no")) {
+  if (Name.starts_with_insensitive("no")) {
     EnableFeature = false;
     Name = Name.substr(2);
   }
diff --git a/llvm/lib/Target/MSP430/AsmParser/MSP430AsmParser.cpp b/llvm/lib/Target/MSP430/AsmParser/MSP430AsmParser.cpp
--- a/llvm/lib/Target/MSP430/AsmParser/MSP430AsmParser.cpp
+++ b/llvm/lib/Target/MSP430/AsmParser/MSP430AsmParser.cpp
@@ -330,7 +330,7 @@
 bool MSP430AsmParser::parseJccInstruction(ParseInstructionInfo &Info,
                                           StringRef Name, SMLoc NameLoc,
                                           OperandVector &Operands) {
-  if (!Name.startswith_insensitive("j"))
+  if (!Name.starts_with_insensitive("j"))
     return true;
 
   auto CC = Name.drop_front().lower();
@@ -393,7 +393,7 @@
                                        StringRef Name, SMLoc NameLoc,
                                        OperandVector &Operands) {
   // Drop .w suffix
-  if (Name.endswith_insensitive(".w"))
+  if (Name.ends_with_insensitive(".w"))
     Name = Name.drop_back(2);
 
   if (!parseJccInstruction(Info, Name, NameLoc, Operands))
diff --git a/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp b/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp
--- a/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp
+++ b/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp
@@ -1278,40 +1278,40 @@
   } else if (Name.equals_insensitive("vrsave")) {
     RegNo = PPC::VRSAVE;
     IntVal = 256;
-  } else if (Name.startswith_insensitive("r") &&
+  } else if (Name.starts_with_insensitive("r") &&
              !Name.substr(1).getAsInteger(10, IntVal) && IntVal < 32) {
     RegNo = isPPC64() ? XRegs[IntVal] : RRegs[IntVal];
-  } else if (Name.startswith_insensitive("f") &&
+  } else if (Name.starts_with_insensitive("f") &&
              !Name.substr(1).getAsInteger(10, IntVal) && IntVal < 32) {
     RegNo = FRegs[IntVal];
-  } else if (Name.startswith_insensitive("vs") &&
+  } else if (Name.starts_with_insensitive("vs") &&
              !Name.substr(2).getAsInteger(10, IntVal) && IntVal < 64) {
     RegNo = VSRegs[IntVal];
-  } else if (Name.startswith_insensitive("v") &&
+  } else if (Name.starts_with_insensitive("v") &&
              !Name.substr(1).getAsInteger(10, IntVal) && IntVal < 32) {
     RegNo = VRegs[IntVal];
-  } else if (Name.startswith_insensitive("cr") &&
+  } else if (Name.starts_with_insensitive("cr") &&
              !Name.substr(2).getAsInteger(10, IntVal) && IntVal < 8) {
     RegNo = CRRegs[IntVal];
-  } else if (Name.startswith_insensitive("acc") &&
+  } else if (Name.starts_with_insensitive("acc") &&
              !Name.substr(3).getAsInteger(10, IntVal) && IntVal < 8) {
     RegNo = ACCRegs[IntVal];
-  } else if (Name.startswith_insensitive("wacc_hi") &&
+  } else if (Name.starts_with_insensitive("wacc_hi") &&
              !Name.substr(7).getAsInteger(10, IntVal) && IntVal < 8) {
     RegNo = ACCRegs[IntVal];
-  } else if (Name.startswith_insensitive("wacc") &&
+  } else if (Name.starts_with_insensitive("wacc") &&
              !Name.substr(4).getAsInteger(10, IntVal) && IntVal < 8) {
     RegNo = WACCRegs[IntVal];
-  } else if (Name.startswith_insensitive("dmrrowp") &&
+  } else if (Name.starts_with_insensitive("dmrrowp") &&
              !Name.substr(7).getAsInteger(10, IntVal) && IntVal < 32) {
     RegNo = DMRROWpRegs[IntVal];
-  } else if (Name.startswith_insensitive("dmrrow") &&
+  } else if (Name.starts_with_insensitive("dmrrow") &&
              !Name.substr(6).getAsInteger(10, IntVal) && IntVal < 64) {
     RegNo = DMRROWRegs[IntVal];
-  } else if (Name.startswith_insensitive("dmrp") &&
+  } else if (Name.starts_with_insensitive("dmrp") &&
              !Name.substr(4).getAsInteger(10, IntVal) && IntVal < 4) {
     RegNo = DMRROWpRegs[IntVal];
-  } else if (Name.startswith_insensitive("dmr") &&
+  } else if (Name.starts_with_insensitive("dmr") &&
              !Name.substr(3).getAsInteger(10, IntVal) && IntVal < 8) {
     RegNo = DMRRegs[IntVal];
   } else
diff --git a/llvm/lib/WindowsDriver/MSVCPaths.cpp b/llvm/lib/WindowsDriver/MSVCPaths.cpp
--- a/llvm/lib/WindowsDriver/MSVCPaths.cpp
+++ b/llvm/lib/WindowsDriver/MSVCPaths.cpp
@@ -586,7 +586,7 @@
         for (StringRef Prefix : ExpectedPrefixes) {
           if (It == End)
             goto NotAToolChain;
-          if (!It->startswith_insensitive(Prefix))
+          if (!It->starts_with_insensitive(Prefix))
             goto NotAToolChain;
           ++It;
         }
diff --git a/llvm/tools/bugpoint/ToolRunner.cpp b/llvm/tools/bugpoint/ToolRunner.cpp
--- a/llvm/tools/bugpoint/ToolRunner.cpp
+++ b/llvm/tools/bugpoint/ToolRunner.cpp
@@ -612,7 +612,7 @@
     ++I;
     if (I == Args.size())
       break;
-    if (Args[I].startswith_insensitive("arm"))
+    if (Args[I].starts_with_insensitive("arm"))
       return true;
   }
 
diff --git a/llvm/tools/llvm-cov/llvm-cov.cpp b/llvm/tools/llvm-cov/llvm-cov.cpp
--- a/llvm/tools/llvm-cov/llvm-cov.cpp
+++ b/llvm/tools/llvm-cov/llvm-cov.cpp
@@ -59,7 +59,7 @@
   InitLLVM X(argc, argv);
 
   // If argv[0] is or ends with 'gcov', always be gcov compatible
-  if (sys::path::stem(argv[0]).endswith_insensitive("gcov"))
+  if (sys::path::stem(argv[0]).ends_with_insensitive("gcov"))
     return gcovMain(argc, argv);
 
   // Check if we are invoking a specific tool command.
diff --git a/llvm/tools/llvm-jitlink/llvm-jitlink.cpp b/llvm/tools/llvm-jitlink/llvm-jitlink.cpp
--- a/llvm/tools/llvm-jitlink/llvm-jitlink.cpp
+++ b/llvm/tools/llvm-jitlink/llvm-jitlink.cpp
@@ -554,12 +554,12 @@
 
   uint64_t Units = 1024;
 
-  if (SizeString.endswith_insensitive("kb"))
+  if (SizeString.ends_with_insensitive("kb"))
     SizeString = SizeString.drop_back(2).rtrim();
-  else if (SizeString.endswith_insensitive("mb")) {
+  else if (SizeString.ends_with_insensitive("mb")) {
     Units = 1024 * 1024;
     SizeString = SizeString.drop_back(2).rtrim();
-  } else if (SizeString.endswith_insensitive("gb")) {
+  } else if (SizeString.ends_with_insensitive("gb")) {
     Units = 1024 * 1024 * 1024;
     SizeString = SizeString.drop_back(2).rtrim();
   }
@@ -1008,7 +1008,7 @@
     }
   } else if (TT.isOSBinFormatCOFF() && !OrcRuntime.empty()) {
     auto LoadDynLibrary = [&, this](JITDylib &JD, StringRef DLLName) -> Error {
-      if (!DLLName.endswith_insensitive(".dll"))
+      if (!DLLName.ends_with_insensitive(".dll"))
         return make_error<StringError>("DLLName not ending with .dll",
                                        inconvertibleErrorCode());
       return loadAndLinkDynamicLibrary(JD, DLLName);
@@ -1648,7 +1648,7 @@
     for (auto FileName : (*G)->getImportedDynamicLibraries()) {
       LibraryLoad NewLL;
       auto FileNameRef = StringRef(FileName);
-      if (!FileNameRef.endswith_insensitive(".dll"))
+      if (!FileNameRef.ends_with_insensitive(".dll"))
         return make_error<StringError>(
             "COFF Imported library not ending with dll extension?",
             inconvertibleErrorCode());
diff --git a/llvm/tools/llvm-rc/ResourceFileWriter.cpp b/llvm/tools/llvm-rc/ResourceFileWriter.cpp
--- a/llvm/tools/llvm-rc/ResourceFileWriter.cpp
+++ b/llvm/tools/llvm-rc/ResourceFileWriter.cpp
@@ -99,7 +99,7 @@
     return false;
 
   // Just take the contents of the string, checking if it's been marked long.
-  IsLongString = Str.startswith_insensitive("L");
+  IsLongString = Str.starts_with_insensitive("L");
   if (IsLongString)
     Str = Str.drop_front();