diff --git a/clang/include/clang/Basic/ObjCRuntime.h b/clang/include/clang/Basic/ObjCRuntime.h
index d783154c3f9f1..500b2462f0077 100644
--- a/clang/include/clang/Basic/ObjCRuntime.h
+++ b/clang/include/clang/Basic/ObjCRuntime.h
@@ -482,7 +482,7 @@ class ObjCRuntime {
     return llvm::hash_combine(OCR.getKind(), OCR.getVersion());
   }
 
-  template <typename HasherT, llvm::support::endianness Endianness>
+  template <typename HasherT, llvm::endianness Endianness>
   friend void addHash(llvm::HashBuilder<HasherT, Endianness> &HBuilder,
                       const ObjCRuntime &OCR) {
     HBuilder.add(OCR.getKind(), OCR.getVersion());
diff --git a/clang/include/clang/Basic/Sanitizers.h b/clang/include/clang/Basic/Sanitizers.h
index 090a3a7fa9076..8fdaf2e4ba8ab 100644
--- a/clang/include/clang/Basic/Sanitizers.h
+++ b/clang/include/clang/Basic/Sanitizers.h
@@ -77,7 +77,7 @@ class SanitizerMask {
 
   llvm::hash_code hash_value() const;
 
-  template <typename HasherT, llvm::support::endianness Endianness>
+  template <typename HasherT, llvm::endianness Endianness>
   friend void addHash(llvm::HashBuilder<HasherT, Endianness> &HBuilder,
                       const SanitizerMask &SM) {
     HBuilder.addRange(&SM.maskLoToHigh[0], &SM.maskLoToHigh[kNumElem]);
diff --git a/clang/include/clang/Lex/HeaderSearchOptions.h b/clang/include/clang/Lex/HeaderSearchOptions.h
index 206bc69d7b2cd..c7d95006bb779 100644
--- a/clang/include/clang/Lex/HeaderSearchOptions.h
+++ b/clang/include/clang/Lex/HeaderSearchOptions.h
@@ -267,7 +267,7 @@ inline llvm::hash_code hash_value(const HeaderSearchOptions::Entry &E) {
   return llvm::hash_combine(E.Path, E.Group, E.IsFramework, E.IgnoreSysRoot);
 }
 
-template <typename HasherT, llvm::support::endianness Endianness>
+template <typename HasherT, llvm::endianness Endianness>
 inline void addHash(llvm::HashBuilder<HasherT, Endianness> &HBuilder,
                     const HeaderSearchOptions::Entry &E) {
   HBuilder.add(E.Path, E.Group, E.IsFramework, E.IgnoreSysRoot);
@@ -278,7 +278,7 @@ hash_value(const HeaderSearchOptions::SystemHeaderPrefix &SHP) {
   return llvm::hash_combine(SHP.Prefix, SHP.IsSystemHeader);
 }
 
-template <typename HasherT, llvm::support::endianness Endianness>
+template <typename HasherT, llvm::endianness Endianness>
 inline void addHash(llvm::HashBuilder<HasherT, Endianness> &HBuilder,
                     const HeaderSearchOptions::SystemHeaderPrefix &SHP) {
   HBuilder.add(SHP.Prefix, SHP.IsSystemHeader);
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index f2fe9046a6c1f..bb442495f5835 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -4630,7 +4630,7 @@ bool CompilerInvocation::CreateFromArgs(CompilerInvocation &Invocation,
 
 std::string CompilerInvocation::getModuleHash() const {
   // FIXME: Consider using SHA1 instead of MD5.
-  llvm::HashBuilder<llvm::MD5, llvm::support::endianness::native> HBuilder;
+  llvm::HashBuilder<llvm::MD5, llvm::endianness::native> HBuilder;
 
   // Note: For QoI reasons, the things we use as a hash here should all be
   // dumped via the -module-info flag.
diff --git a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
index 5e028c4431fe9..40115b7b5ae25 100644
--- a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
+++ b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
@@ -295,8 +295,7 @@ void ModuleDepCollector::applyDiscoveredDependencies(CompilerInvocation &CI) {
 static std::string getModuleContextHash(const ModuleDeps &MD,
                                         const CowCompilerInvocation &CI,
                                         bool EagerLoadModules) {
-  llvm::HashBuilder<llvm::TruncatedBLAKE3<16>,
-                    llvm::support::endianness::native>
+  llvm::HashBuilder<llvm::TruncatedBLAKE3<16>, llvm::endianness::native>
       HashBuilder;
   SmallString<32> Scratch;
 
diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h
index 6a094c4c0ad82..56229334f9a44 100644
--- a/lld/ELF/Config.h
+++ b/lld/ELF/Config.h
@@ -366,7 +366,7 @@ struct Config {
   bool isLE;
 
   // endianness::little if isLE is true. endianness::big otherwise.
-  llvm::support::endianness endianness;
+  llvm::endianness endianness;
 
   // True if the target is the little-endian MIPS64.
   //
diff --git a/lldb/unittests/tools/lldb-server/tests/MessageObjects.cpp b/lldb/unittests/tools/lldb-server/tests/MessageObjects.cpp
index f131bd98c2e84..2c6b9a2299dd7 100644
--- a/lldb/unittests/tools/lldb-server/tests/MessageObjects.cpp
+++ b/lldb/unittests/tools/lldb-server/tests/MessageObjects.cpp
@@ -201,7 +201,7 @@ Expected<RegisterInfo> RegisterInfoParser::create(StringRef Response) {
 
 Expected<RegisterValue> parseRegisterValue(const RegisterInfo &Info,
                                            StringRef HexValue,
-                                           llvm::support::endianness Endian,
+                                           llvm::endianness Endian,
                                            bool ZeroPad) {
   SmallString<128> Storage;
   if (ZeroPad && HexValue.size() < Info.byte_size * 2) {
@@ -224,7 +224,7 @@ Expected<RegisterValue> parseRegisterValue(const RegisterInfo &Info,
 
 //====== StopReply =============================================================
 Expected<std::unique_ptr<StopReply>>
-StopReply::create(StringRef Response, llvm::support::endianness Endian,
+StopReply::create(StringRef Response, llvm::endianness Endian,
                   ArrayRef<RegisterInfo> RegInfos) {
   if (Response.size() < 3)
     return make_parsing_error("StopReply: Invalid packet");
diff --git a/lldb/unittests/tools/lldb-server/tests/MessageObjects.h b/lldb/unittests/tools/lldb-server/tests/MessageObjects.h
index ff3f76ae3f04e..0e0a3b2a92726 100644
--- a/lldb/unittests/tools/lldb-server/tests/MessageObjects.h
+++ b/lldb/unittests/tools/lldb-server/tests/MessageObjects.h
@@ -31,7 +31,7 @@ class ProcessInfo : public Parser<ProcessInfo> {
 public:
   static llvm::Expected<ProcessInfo> create(llvm::StringRef response);
   lldb::pid_t GetPid() const;
-  llvm::support::endianness GetEndian() const;
+  llvm::endianness GetEndian() const;
 
 private:
   ProcessInfo() = default;
@@ -43,7 +43,7 @@ class ProcessInfo : public Parser<ProcessInfo> {
   uint32_t m_effective_gid;
   std::string m_triple;
   llvm::SmallString<16> m_ostype;
-  llvm::support::endianness m_endian;
+  llvm::endianness m_endian;
   unsigned int m_ptrsize;
 };
 
@@ -85,7 +85,7 @@ struct RegisterInfoParser : public Parser<lldb_private::RegisterInfo> {
 
 llvm::Expected<lldb_private::RegisterValue>
 parseRegisterValue(const lldb_private::RegisterInfo &Info,
-                   llvm::StringRef HexValue, llvm::support::endianness Endian,
+                   llvm::StringRef HexValue, llvm::endianness Endian,
                    bool ZeroPad = false);
 
 class StopReply : public Parser<std::unique_ptr<StopReply>> {
@@ -94,7 +94,7 @@ class StopReply : public Parser<std::unique_ptr<StopReply>> {
   virtual ~StopReply() = default;
 
   static llvm::Expected<std::unique_ptr<StopReply>>
-  create(llvm::StringRef Response, llvm::support::endianness Endian,
+  create(llvm::StringRef Response, llvm::endianness Endian,
          llvm::ArrayRef<lldb_private::RegisterInfo> RegInfos);
 
   // for llvm::cast<>
@@ -114,7 +114,7 @@ class StopReplyStop : public StopReply {
         Reason(Reason) {}
 
   static llvm::Expected<std::unique_ptr<StopReplyStop>>
-  create(llvm::StringRef Response, llvm::support::endianness Endian,
+  create(llvm::StringRef Response, llvm::endianness Endian,
          llvm::ArrayRef<lldb_private::RegisterInfo> RegInfos);
 
   const RegisterMap &getThreadPcs() const { return ThreadPcs; }
@@ -131,7 +131,7 @@ class StopReplyStop : public StopReply {
 private:
   static llvm::Expected<RegisterMap> parseRegisters(
       const llvm::StringMap<llvm::SmallVector<llvm::StringRef, 2>> &Elements,
-      llvm::support::endianness Endian,
+      llvm::endianness Endian,
       llvm::ArrayRef<lldb_private::RegisterInfo> RegInfos);
 
   uint8_t Signal;
diff --git a/llvm/include/llvm/DebugInfo/GSYM/FileWriter.h b/llvm/include/llvm/DebugInfo/GSYM/FileWriter.h
index 74811240e0b5e..b6bfcb115d8a2 100644
--- a/llvm/include/llvm/DebugInfo/GSYM/FileWriter.h
+++ b/llvm/include/llvm/DebugInfo/GSYM/FileWriter.h
@@ -28,9 +28,10 @@ namespace gsym {
 /// offsets and sizes.
 class FileWriter {
   llvm::raw_pwrite_stream &OS;
-  llvm::support::endianness ByteOrder;
+  llvm::endianness ByteOrder;
+
 public:
-  FileWriter(llvm::raw_pwrite_stream &S, llvm::support::endianness B)
+  FileWriter(llvm::raw_pwrite_stream &S, llvm::endianness B)
       : OS(S), ByteOrder(B) {}
   ~FileWriter();
   /// Write a single uint8_t value into the stream at the current file
@@ -113,7 +114,7 @@ class FileWriter {
     return OS;
   }
 
-  llvm::support::endianness getByteOrder() const { return ByteOrder; }
+  llvm::endianness getByteOrder() const { return ByteOrder; }
 
 private:
   FileWriter(const FileWriter &rhs) = delete;
diff --git a/llvm/include/llvm/DebugInfo/GSYM/GsymCreator.h b/llvm/include/llvm/DebugInfo/GSYM/GsymCreator.h
index fd9204dba80ef..bb52f3f2cd56b 100644
--- a/llvm/include/llvm/DebugInfo/GSYM/GsymCreator.h
+++ b/llvm/include/llvm/DebugInfo/GSYM/GsymCreator.h
@@ -278,8 +278,7 @@ class GsymCreator {
   /// \param Path The path prefix to use when saving the GSYM files.
   /// \param ByteOrder The endianness to use when saving the file.
   /// \param SegmentSize The size in bytes to segment the GSYM file into.
-  llvm::Error saveSegments(StringRef Path,
-                           llvm::support::endianness ByteOrder,
+  llvm::Error saveSegments(StringRef Path, llvm::endianness ByteOrder,
                            uint64_t SegmentSize) const;
 
   /// Let this creator know that this is a segment of another GsymCreator.
@@ -308,7 +307,7 @@ class GsymCreator {
   ///                    a single GSYM file that contains all function
   ///                    information will be created.
   /// \returns An error object that indicates success or failure of the save.
-  llvm::Error save(StringRef Path, llvm::support::endianness ByteOrder,
+  llvm::Error save(StringRef Path, llvm::endianness ByteOrder,
                    std::optional<uint64_t> SegmentSize = std::nullopt) const;
 
   /// Encode a GSYM into the file writer stream at the current position.
diff --git a/llvm/include/llvm/DebugInfo/GSYM/GsymReader.h b/llvm/include/llvm/DebugInfo/GSYM/GsymReader.h
index 5c0ab87dca303..cd4fdfa0e9e37 100644
--- a/llvm/include/llvm/DebugInfo/GSYM/GsymReader.h
+++ b/llvm/include/llvm/DebugInfo/GSYM/GsymReader.h
@@ -47,7 +47,7 @@ class GsymReader {
 
   std::unique_ptr<MemoryBuffer> MemBuffer;
   StringRef GsymBytes;
-  llvm::support::endianness Endian;
+  llvm::endianness Endian;
   const Header *Hdr = nullptr;
   ArrayRef<uint8_t> AddrOffsets;
   ArrayRef<uint32_t> AddrInfoOffsets;
diff --git a/llvm/include/llvm/Support/BinaryByteStream.h b/llvm/include/llvm/Support/BinaryByteStream.h
index 474a8df3ab381..d313994fd5b43 100644
--- a/llvm/include/llvm/Support/BinaryByteStream.h
+++ b/llvm/include/llvm/Support/BinaryByteStream.h
@@ -30,12 +30,12 @@ namespace llvm {
 class BinaryByteStream : public BinaryStream {
 public:
   BinaryByteStream() = default;
-  BinaryByteStream(ArrayRef<uint8_t> Data, llvm::support::endianness Endian)
+  BinaryByteStream(ArrayRef<uint8_t> Data, llvm::endianness Endian)
       : Endian(Endian), Data(Data) {}
-  BinaryByteStream(StringRef Data, llvm::support::endianness Endian)
+  BinaryByteStream(StringRef Data, llvm::endianness Endian)
       : Endian(Endian), Data(Data.bytes_begin(), Data.bytes_end()) {}
 
-  llvm::support::endianness getEndian() const override { return Endian; }
+  llvm::endianness getEndian() const override { return Endian; }
 
   Error readBytes(uint64_t Offset, uint64_t Size,
                   ArrayRef<uint8_t> &Buffer) override {
@@ -63,7 +63,7 @@ class BinaryByteStream : public BinaryStream {
   }
 
 protected:
-  llvm::support::endianness Endian;
+  llvm::endianness Endian;
   ArrayRef<uint8_t> Data;
 };
 
@@ -74,7 +74,7 @@ class BinaryByteStream : public BinaryStream {
 class MemoryBufferByteStream : public BinaryByteStream {
 public:
   MemoryBufferByteStream(std::unique_ptr<MemoryBuffer> Buffer,
-                         llvm::support::endianness Endian)
+                         llvm::endianness Endian)
       : BinaryByteStream(Buffer->getBuffer(), Endian),
         MemBuffer(std::move(Buffer)) {}
 
@@ -89,10 +89,10 @@ class MutableBinaryByteStream : public WritableBinaryStream {
 public:
   MutableBinaryByteStream() = default;
   MutableBinaryByteStream(MutableArrayRef<uint8_t> Data,
-                          llvm::support::endianness Endian)
+                          llvm::endianness Endian)
       : Data(Data), ImmutableStream(Data, Endian) {}
 
-  llvm::support::endianness getEndian() const override {
+  llvm::endianness getEndian() const override {
     return ImmutableStream.getEndian();
   }
 
@@ -133,16 +133,15 @@ class MutableBinaryByteStream : public WritableBinaryStream {
 /// causing the underlying data to grow.  This class owns the underlying data.
 class AppendingBinaryByteStream : public WritableBinaryStream {
   std::vector<uint8_t> Data;
-  llvm::support::endianness Endian = llvm::support::little;
+  llvm::endianness Endian = llvm::support::little;
 
 public:
   AppendingBinaryByteStream() = default;
-  AppendingBinaryByteStream(llvm::support::endianness Endian)
-      : Endian(Endian) {}
+  AppendingBinaryByteStream(llvm::endianness Endian) : Endian(Endian) {}
 
   void clear() { Data.clear(); }
 
-  llvm::support::endianness getEndian() const override { return Endian; }
+  llvm::endianness getEndian() const override { return Endian; }
 
   Error readBytes(uint64_t Offset, uint64_t Size,
                   ArrayRef<uint8_t> &Buffer) override {
@@ -204,7 +203,7 @@ class FileBufferByteStream : public WritableBinaryStream {
   class StreamImpl : public MutableBinaryByteStream {
   public:
     StreamImpl(std::unique_ptr<FileOutputBuffer> Buffer,
-               llvm::support::endianness Endian)
+               llvm::endianness Endian)
         : MutableBinaryByteStream(
               MutableArrayRef<uint8_t>(Buffer->getBufferStart(),
                                        Buffer->getBufferEnd()),
@@ -230,12 +229,10 @@ class FileBufferByteStream : public WritableBinaryStream {
 
 public:
   FileBufferByteStream(std::unique_ptr<FileOutputBuffer> Buffer,
-                       llvm::support::endianness Endian)
+                       llvm::endianness Endian)
       : Impl(std::move(Buffer), Endian) {}
 
-  llvm::support::endianness getEndian() const override {
-    return Impl.getEndian();
-  }
+  llvm::endianness getEndian() const override { return Impl.getEndian(); }
 
   Error readBytes(uint64_t Offset, uint64_t Size,
                   ArrayRef<uint8_t> &Buffer) override {
diff --git a/llvm/include/llvm/Support/BinaryItemStream.h b/llvm/include/llvm/Support/BinaryItemStream.h
index eb512bf4721a8..472ef004744c5 100644
--- a/llvm/include/llvm/Support/BinaryItemStream.h
+++ b/llvm/include/llvm/Support/BinaryItemStream.h
@@ -33,10 +33,9 @@ template <typename T> struct BinaryItemTraits {
 template <typename T, typename Traits = BinaryItemTraits<T>>
 class BinaryItemStream : public BinaryStream {
 public:
-  explicit BinaryItemStream(llvm::support::endianness Endian)
-      : Endian(Endian) {}
+  explicit BinaryItemStream(llvm::endianness Endian) : Endian(Endian) {}
 
-  llvm::support::endianness getEndian() const override { return Endian; }
+  llvm::endianness getEndian() const override { return Endian; }
 
   Error readBytes(uint64_t Offset, uint64_t Size,
                   ArrayRef<uint8_t> &Buffer) override {
@@ -94,7 +93,7 @@ class BinaryItemStream : public BinaryStream {
     return Idx;
   }
 
-  llvm::support::endianness Endian;
+  llvm::endianness Endian;
   ArrayRef<T> Items;
 
   // Sorted vector of offsets to accelerate lookup.
diff --git a/llvm/include/llvm/Support/BinaryStream.h b/llvm/include/llvm/Support/BinaryStream.h
index e87129d8c201f..4a683f7253f0f 100644
--- a/llvm/include/llvm/Support/BinaryStream.h
+++ b/llvm/include/llvm/Support/BinaryStream.h
@@ -36,7 +36,7 @@ class BinaryStream {
 public:
   virtual ~BinaryStream() = default;
 
-  virtual llvm::support::endianness getEndian() const = 0;
+  virtual llvm::endianness getEndian() const = 0;
 
   /// Given an offset into the stream and a number of bytes, attempt to
   /// read the bytes and set the output ArrayRef to point to data owned by the
diff --git a/llvm/include/llvm/Support/BinaryStreamReader.h b/llvm/include/llvm/Support/BinaryStreamReader.h
index 6a608d7167e5a..ca99388c5d03a 100644
--- a/llvm/include/llvm/Support/BinaryStreamReader.h
+++ b/llvm/include/llvm/Support/BinaryStreamReader.h
@@ -31,9 +31,8 @@ class BinaryStreamReader {
   BinaryStreamReader() = default;
   explicit BinaryStreamReader(BinaryStreamRef Ref);
   explicit BinaryStreamReader(BinaryStream &Stream);
-  explicit BinaryStreamReader(ArrayRef<uint8_t> Data,
-                              llvm::support::endianness Endian);
-  explicit BinaryStreamReader(StringRef Data, llvm::support::endianness Endian);
+  explicit BinaryStreamReader(ArrayRef<uint8_t> Data, llvm::endianness Endian);
+  explicit BinaryStreamReader(StringRef Data, llvm::endianness Endian);
 
   BinaryStreamReader(const BinaryStreamReader &Other) = default;
 
diff --git a/llvm/include/llvm/Support/BinaryStreamRef.h b/llvm/include/llvm/Support/BinaryStreamRef.h
index 0cea224527ac5..fdc46f5fd5605 100644
--- a/llvm/include/llvm/Support/BinaryStreamRef.h
+++ b/llvm/include/llvm/Support/BinaryStreamRef.h
@@ -43,9 +43,7 @@ template <class RefType, class StreamType> class BinaryStreamRefBase {
   BinaryStreamRefBase(BinaryStreamRefBase &&Other) = default;
 
 public:
-  llvm::support::endianness getEndian() const {
-    return BorrowedImpl->getEndian();
-  }
+  llvm::endianness getEndian() const { return BorrowedImpl->getEndian(); }
 
   uint64_t getLength() const {
     if (Length)
@@ -165,9 +163,8 @@ class BinaryStreamRef
   BinaryStreamRef(BinaryStream &Stream);
   BinaryStreamRef(BinaryStream &Stream, uint64_t Offset,
                   std::optional<uint64_t> Length);
-  explicit BinaryStreamRef(ArrayRef<uint8_t> Data,
-                           llvm::support::endianness Endian);
-  explicit BinaryStreamRef(StringRef Data, llvm::support::endianness Endian);
+  explicit BinaryStreamRef(ArrayRef<uint8_t> Data, llvm::endianness Endian);
+  explicit BinaryStreamRef(StringRef Data, llvm::endianness Endian);
 
   BinaryStreamRef(const BinaryStreamRef &Other) = default;
   BinaryStreamRef &operator=(const BinaryStreamRef &Other) = default;
@@ -240,7 +237,7 @@ class WritableBinaryStreamRef
   WritableBinaryStreamRef(WritableBinaryStream &Stream, uint64_t Offset,
                           std::optional<uint64_t> Length);
   explicit WritableBinaryStreamRef(MutableArrayRef<uint8_t> Data,
-                                   llvm::support::endianness Endian);
+                                   llvm::endianness Endian);
   WritableBinaryStreamRef(const WritableBinaryStreamRef &Other) = default;
   WritableBinaryStreamRef &
   operator=(const WritableBinaryStreamRef &Other) = default;
diff --git a/llvm/include/llvm/Support/BinaryStreamWriter.h b/llvm/include/llvm/Support/BinaryStreamWriter.h
index 5a56c9fcc46bd..bc1d7949841d6 100644
--- a/llvm/include/llvm/Support/BinaryStreamWriter.h
+++ b/llvm/include/llvm/Support/BinaryStreamWriter.h
@@ -33,7 +33,7 @@ class BinaryStreamWriter {
   explicit BinaryStreamWriter(WritableBinaryStreamRef Ref);
   explicit BinaryStreamWriter(WritableBinaryStream &Stream);
   explicit BinaryStreamWriter(MutableArrayRef<uint8_t> Data,
-                              llvm::support::endianness Endian);
+                              llvm::endianness Endian);
 
   BinaryStreamWriter(const BinaryStreamWriter &Other) = default;
 
diff --git a/llvm/include/llvm/Support/VersionTuple.h b/llvm/include/llvm/Support/VersionTuple.h
index b85500e20d1bd..4d58424657b06 100644
--- a/llvm/include/llvm/Support/VersionTuple.h
+++ b/llvm/include/llvm/Support/VersionTuple.h
@@ -173,7 +173,7 @@ class VersionTuple {
     return hash_combine(VT.Major, VT.Minor, VT.Subminor, VT.Build);
   }
 
-  template <typename HasherT, llvm::support::endianness Endianness>
+  template <typename HasherT, llvm::endianness Endianness>
   friend void addHash(HashBuilder<HasherT, Endianness> &HBuilder,
                       const VersionTuple &VT) {
     HBuilder.add(VT.Major, VT.Minor, VT.Subminor, VT.Build);
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index 4ff056042c6f9..a41d0357bf343 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -3353,7 +3353,7 @@ void CodeViewDebug::emitConstantSymbolRecord(const DIType *DTy, APSInt &Value,
 
   // Encoded integers shouldn't need more than 10 bytes.
   uint8_t Data[10];
-  BinaryStreamWriter Writer(Data, llvm::support::endianness::little);
+  BinaryStreamWriter Writer(Data, llvm::endianness::little);
   CodeViewRecordIO IO(Writer);
   cantFail(IO.mapEncodedInteger(Value));
   StringRef SRef((char *)Data, Writer.getOffset());
diff --git a/llvm/lib/DebugInfo/GSYM/GsymCreator.cpp b/llvm/lib/DebugInfo/GSYM/GsymCreator.cpp
index 6006b86aa3858..ee7b0efba5ea4 100644
--- a/llvm/lib/DebugInfo/GSYM/GsymCreator.cpp
+++ b/llvm/lib/DebugInfo/GSYM/GsymCreator.cpp
@@ -61,9 +61,7 @@ uint32_t GsymCreator::copyFile(const GsymCreator &SrcGC, uint32_t FileIdx) {
   return insertFileEntry(DstFE);
 }
 
-
-llvm::Error GsymCreator::save(StringRef Path,
-                              llvm::support::endianness ByteOrder,
+llvm::Error GsymCreator::save(StringRef Path, llvm::endianness ByteOrder,
                               std::optional<uint64_t> SegmentSize) const {
   if (SegmentSize)
     return saveSegments(Path, ByteOrder, *SegmentSize);
@@ -478,7 +476,7 @@ uint64_t GsymCreator::copyFunctionInfo(const GsymCreator &SrcGC, size_t FuncIdx)
 }
 
 llvm::Error GsymCreator::saveSegments(StringRef Path,
-                                      llvm::support::endianness ByteOrder,
+                                      llvm::endianness ByteOrder,
                                       uint64_t SegmentSize) const {
   if (SegmentSize == 0)
     return createStringError(std::errc::invalid_argument,
diff --git a/llvm/lib/ProfileData/InstrProfReader.cpp b/llvm/lib/ProfileData/InstrProfReader.cpp
index 125184d402084..f3fd7fee4f45f 100644
--- a/llvm/lib/ProfileData/InstrProfReader.cpp
+++ b/llvm/lib/ProfileData/InstrProfReader.cpp
@@ -92,7 +92,7 @@ readBinaryIdsInternal(const MemoryBuffer &DataBuffer,
                       const uint64_t BinaryIdsSize,
                       const uint8_t *BinaryIdsStart,
                       std::vector<llvm::object::BuildID> &BinaryIds,
-                      const llvm::support::endianness Endian) {
+                      const llvm::endianness Endian) {
   using namespace support;
 
   if (BinaryIdsSize == 0)
@@ -145,7 +145,7 @@ static Error printBinaryIdsInternal(raw_ostream &OS,
                                     const MemoryBuffer &DataBuffer,
                                     uint64_t BinaryIdsSize,
                                     const uint8_t *BinaryIdsStart,
-                                    llvm::support::endianness Endian) {
+                                    llvm::endianness Endian) {
   if (BinaryIdsSize == 0)
     return Error::success();
 
diff --git a/llvm/lib/Support/BinaryStreamRef.cpp b/llvm/lib/Support/BinaryStreamRef.cpp
index 0ef00af4fcb7d..acb1dff889f5c 100644
--- a/llvm/lib/Support/BinaryStreamRef.cpp
+++ b/llvm/lib/Support/BinaryStreamRef.cpp
@@ -18,9 +18,7 @@ class ArrayRefImpl : public BinaryStream {
 public:
   ArrayRefImpl(ArrayRef<uint8_t> Data, endianness Endian) : BBS(Data, Endian) {}
 
-  llvm::support::endianness getEndian() const override {
-    return BBS.getEndian();
-  }
+  llvm::endianness getEndian() const override { return BBS.getEndian(); }
   Error readBytes(uint64_t Offset, uint64_t Size,
                   ArrayRef<uint8_t> &Buffer) override {
     return BBS.readBytes(Offset, Size, Buffer);
@@ -41,9 +39,7 @@ class MutableArrayRefImpl : public WritableBinaryStream {
       : BBS(Data, Endian) {}
 
   // Inherited via WritableBinaryStream
-  llvm::support::endianness getEndian() const override {
-    return BBS.getEndian();
-  }
+  llvm::endianness getEndian() const override { return BBS.getEndian(); }
   Error readBytes(uint64_t Offset, uint64_t Size,
                   ArrayRef<uint8_t> &Buffer) override {
     return BBS.readBytes(Offset, Size, Buffer);
diff --git a/llvm/lib/Support/BinaryStreamWriter.cpp b/llvm/lib/Support/BinaryStreamWriter.cpp
index 3d87a30a86a17..dff08fee3fefa 100644
--- a/llvm/lib/Support/BinaryStreamWriter.cpp
+++ b/llvm/lib/Support/BinaryStreamWriter.cpp
@@ -22,7 +22,7 @@ BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStream &Stream)
     : Stream(Stream) {}
 
 BinaryStreamWriter::BinaryStreamWriter(MutableArrayRef<uint8_t> Data,
-                                       llvm::support::endianness Endian)
+                                       llvm::endianness Endian)
     : Stream(Data, Endian) {}
 
 Error BinaryStreamWriter::writeBytes(ArrayRef<uint8_t> Buffer) {
diff --git a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index def54f95409d6..4063a647bec38 100644
--- a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -166,7 +166,7 @@ class ARMDisassembler : public MCDisassembler {
   DecodeStatus AddThumbPredicate(MCInst&) const;
   void UpdateThumbVFPPredicate(DecodeStatus &, MCInst&) const;
 
-  llvm::support::endianness InstructionEndianness;
+  llvm::endianness InstructionEndianness;
 };
 
 } // end anonymous namespace
diff --git a/llvm/lib/Transforms/Instrumentation/MemProfiler.cpp b/llvm/lib/Transforms/Instrumentation/MemProfiler.cpp
index 453dd00488b8f..8cd06f878897b 100644
--- a/llvm/lib/Transforms/Instrumentation/MemProfiler.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemProfiler.cpp
@@ -628,7 +628,7 @@ static void addCallsiteMetadata(Instruction &I,
 
 static uint64_t computeStackId(GlobalValue::GUID Function, uint32_t LineOffset,
                                uint32_t Column) {
-  llvm::HashBuilder<llvm::TruncatedBLAKE3<8>, llvm::support::endianness::little>
+  llvm::HashBuilder<llvm::TruncatedBLAKE3<8>, llvm::endianness::little>
       HashBuilder;
   HashBuilder.add(Function, LineOffset, Column);
   llvm::BLAKE3Result<8> Hash = HashBuilder.final();
diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index fcfce7764e012..d3edc85e46a5a 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -783,12 +783,12 @@ class ARMPrettyPrinter : public PrettyPrinter {
       OS << "\t<unknown>";
   }
 
-  void setInstructionEndianness(llvm::support::endianness Endianness) {
+  void setInstructionEndianness(llvm::endianness Endianness) {
     InstructionEndianness = Endianness;
   }
 
 private:
-  llvm::support::endianness InstructionEndianness = llvm::support::little;
+  llvm::endianness InstructionEndianness = llvm::support::little;
 };
 ARMPrettyPrinter ARMPrettyPrinterInst;
 
diff --git a/llvm/unittests/ADT/HashingTest.cpp b/llvm/unittests/ADT/HashingTest.cpp
index d175f8afee34a..ab13ee833ce55 100644
--- a/llvm/unittests/ADT/HashingTest.cpp
+++ b/llvm/unittests/ADT/HashingTest.cpp
@@ -424,7 +424,7 @@ TEST(HashingTest, HashCombineArgs18) {
 struct StructWithHashBuilderSupport {
   char C;
   int I;
-  template <typename HasherT, llvm::support::endianness Endianness>
+  template <typename HasherT, llvm::endianness Endianness>
   friend void addHash(llvm::HashBuilder<HasherT, Endianness> &HBuilder,
                       const StructWithHashBuilderSupport &Value) {
     HBuilder.add(Value.C, Value.I);
@@ -439,7 +439,7 @@ TEST(HashingTest, HashWithHashBuilder) {
 struct StructWithHashBuilderAndHashValueSupport {
   char C;
   int I;
-  template <typename HasherT, llvm::support::endianness Endianness>
+  template <typename HasherT, llvm::endianness Endianness>
   friend void addHash(llvm::HashBuilder<HasherT, Endianness> &HBuilder,
                       const StructWithHashBuilderAndHashValueSupport &Value) {}
   friend hash_code
diff --git a/llvm/unittests/DebugInfo/GSYM/GSYMTest.cpp b/llvm/unittests/DebugInfo/GSYM/GSYMTest.cpp
index 481a83fa535e8..3f40ff56d7829 100644
--- a/llvm/unittests/DebugInfo/GSYM/GSYMTest.cpp
+++ b/llvm/unittests/DebugInfo/GSYM/GSYMTest.cpp
@@ -176,7 +176,7 @@ TEST(GSYMTest, TestFunctionInfo) {
   EXPECT_LT(FIWithLines, FIWithLinesWithHigherAddress);
 }
 
-static void TestFunctionInfoDecodeError(llvm::support::endianness ByteOrder,
+static void TestFunctionInfoDecodeError(llvm::endianness ByteOrder,
                                         StringRef Bytes,
                                         const uint64_t BaseAddr,
                                         std::string ExpectedErrorMsg) {
@@ -192,7 +192,7 @@ static void TestFunctionInfoDecodeError(llvm::support::endianness ByteOrder,
 TEST(GSYMTest, TestFunctionInfoDecodeErrors) {
   // Test decoding FunctionInfo objects that ensure we report an appropriate
   // error message.
-  const llvm::support::endianness ByteOrder = llvm::support::little;
+  const llvm::endianness ByteOrder = llvm::support::little;
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   FileWriter FW(OutStrm, ByteOrder);
@@ -220,9 +220,9 @@ TEST(GSYMTest, TestFunctionInfoDecodeErrors) {
       "0x00000008: unsupported InfoType 4");
 }
 
-static void TestFunctionInfoEncodeError(llvm::support::endianness ByteOrder,
-                                      const FunctionInfo &FI,
-                                      std::string ExpectedErrorMsg) {
+static void TestFunctionInfoEncodeError(llvm::endianness ByteOrder,
+                                        const FunctionInfo &FI,
+                                        std::string ExpectedErrorMsg) {
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   FileWriter FW(OutStrm, ByteOrder);
@@ -255,7 +255,7 @@ TEST(GSYMTest, TestFunctionInfoEncodeErrors) {
       "attempted to encode invalid InlineInfo object");
 }
 
-static void TestFunctionInfoEncodeDecode(llvm::support::endianness ByteOrder,
+static void TestFunctionInfoEncodeDecode(llvm::endianness ByteOrder,
                                          const FunctionInfo &FI) {
   // Test encoding and decoding FunctionInfo objects.
   SmallString<512> Str;
@@ -332,7 +332,7 @@ TEST(GSYMTest, TestFunctionInfoEncoding) {
   TestFunctionInfoEncodeDecode(llvm::support::big, FIBoth);
 }
 
-static void TestInlineInfoEncodeDecode(llvm::support::endianness ByteOrder,
+static void TestInlineInfoEncodeDecode(llvm::endianness ByteOrder,
                                        const InlineInfo &Inline) {
   // Test encoding and decoding InlineInfo objects
   SmallString<512> Str;
@@ -351,7 +351,7 @@ static void TestInlineInfoEncodeDecode(llvm::support::endianness ByteOrder,
   EXPECT_EQ(Inline, Decoded.get());
 }
 
-static void TestInlineInfoDecodeError(llvm::support::endianness ByteOrder,
+static void TestInlineInfoDecodeError(llvm::endianness ByteOrder,
                                       StringRef Bytes, const uint64_t BaseAddr,
                                       std::string ExpectedErrorMsg) {
   uint8_t AddressSize = 4;
@@ -363,7 +363,7 @@ static void TestInlineInfoDecodeError(llvm::support::endianness ByteOrder,
   checkError(ExpectedErrorMsg, Decoded.takeError());
 }
 
-static void TestInlineInfoEncodeError(llvm::support::endianness ByteOrder,
+static void TestInlineInfoEncodeError(llvm::endianness ByteOrder,
                                       const InlineInfo &Inline,
                                       std::string ExpectedErrorMsg) {
   SmallString<512> Str;
@@ -509,7 +509,7 @@ TEST(GSYMTest, TestInlineInfoEncodeErrors) {
 TEST(GSYMTest, TestInlineInfoDecodeErrors) {
   // Test decoding InlineInfo objects that ensure we report an appropriate
   // error message.
-  const llvm::support::endianness ByteOrder = llvm::support::little;
+  const llvm::endianness ByteOrder = llvm::support::little;
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   FileWriter FW(OutStrm, ByteOrder);
@@ -571,7 +571,7 @@ TEST(GSYMTest, TestStringTable) {
   EXPECT_EQ(StrTab.getString(13), "");
 }
 
-static void TestFileWriterHelper(llvm::support::endianness ByteOrder) {
+static void TestFileWriterHelper(llvm::endianness ByteOrder) {
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   FileWriter FW(OutStrm, ByteOrder);
@@ -686,7 +686,7 @@ TEST(GSYMTest, TestAddressRangesEncodeDecode) {
   TestAddressRangeEncodeDecodeHelper(Ranges, BaseAddr);
 }
 
-static void TestLineTableHelper(llvm::support::endianness ByteOrder,
+static void TestLineTableHelper(llvm::endianness ByteOrder,
                                 const LineTable &LT) {
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
@@ -762,7 +762,7 @@ TEST(GSYMTest, TestLineTable) {
   ASSERT_FALSE(LT2 < LT2);
 }
 
-static void TestLineTableDecodeError(llvm::support::endianness ByteOrder,
+static void TestLineTableDecodeError(llvm::endianness ByteOrder,
                                      StringRef Bytes, const uint64_t BaseAddr,
                                      std::string ExpectedErrorMsg) {
   uint8_t AddressSize = 4;
@@ -777,7 +777,7 @@ static void TestLineTableDecodeError(llvm::support::endianness ByteOrder,
 TEST(GSYMTest, TestLineTableDecodeErrors) {
   // Test decoding InlineInfo objects that ensure we report an appropriate
   // error message.
-  const llvm::support::endianness ByteOrder = llvm::support::little;
+  const llvm::endianness ByteOrder = llvm::support::little;
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   FileWriter FW(OutStrm, ByteOrder);
@@ -813,7 +813,7 @@ TEST(GSYMTest, TestLineTableDecodeErrors) {
 TEST(GSYMTest, TestLineTableEncodeErrors) {
   const uint64_t BaseAddr = 0x1000;
   const uint32_t FileIdx = 1;
-  const llvm::support::endianness ByteOrder = llvm::support::little;
+  const llvm::endianness ByteOrder = llvm::support::little;
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   FileWriter FW(OutStrm, ByteOrder);
@@ -897,7 +897,7 @@ TEST(GSYMTest, TestHeaderEncodeErrors) {
 }
 
 TEST(GSYMTest, TestHeaderDecodeErrors) {
-  const llvm::support::endianness ByteOrder = llvm::support::little;
+  const llvm::endianness ByteOrder = llvm::support::little;
   SmallString<512> Str;
   raw_svector_ostream OutStrm(Str);
   FileWriter FW(OutStrm, ByteOrder);
@@ -941,7 +941,7 @@ TEST(GSYMTest, TestHeaderEncodeDecode) {
   TestHeaderEncodeDecode(H, llvm::support::big);
 }
 
-static void TestGsymCreatorEncodeError(llvm::support::endianness ByteOrder,
+static void TestGsymCreatorEncodeError(llvm::endianness ByteOrder,
                                        const GsymCreator &GC,
                                        std::string ExpectedErrorMsg) {
   SmallString<512> Str;
diff --git a/llvm/unittests/Support/HashBuilderTest.cpp b/llvm/unittests/Support/HashBuilderTest.cpp
index 7738897be4e00..461b7c3b25d89 100644
--- a/llvm/unittests/Support/HashBuilderTest.cpp
+++ b/llvm/unittests/Support/HashBuilderTest.cpp
@@ -21,10 +21,10 @@
 
 // gtest utilities and macros rely on using a single type. So wrap both the
 // hasher type and endianness.
-template <typename _HasherT, llvm::support::endianness _Endianness>
+template <typename _HasherT, llvm::endianness _Endianness>
 struct HasherTAndEndianness {
   using HasherT = _HasherT;
-  static constexpr llvm::support::endianness Endianness = _Endianness;
+  static constexpr llvm::endianness Endianness = _Endianness;
 };
 using HasherTAndEndiannessToTest =
     ::testing::Types<HasherTAndEndianness<llvm::MD5, llvm::support::big>,
@@ -124,7 +124,7 @@ struct SimpleStruct {
   int I;
 };
 
-template <typename HasherT, llvm::support::endianness Endianness>
+template <typename HasherT, llvm::endianness Endianness>
 void addHash(llvm::HashBuilder<HasherT, Endianness> &HBuilder,
              const SimpleStruct &Value) {
   HBuilder.add(Value.C);
@@ -138,7 +138,7 @@ struct StructWithoutCopyOrMove {
   StructWithoutCopyOrMove(const StructWithoutCopyOrMove &) = delete;
   StructWithoutCopyOrMove &operator=(const StructWithoutCopyOrMove &) = delete;
 
-  template <typename HasherT, llvm::support::endianness Endianness>
+  template <typename HasherT, llvm::endianness Endianness>
   friend void addHash(llvm::HashBuilder<HasherT, Endianness> &HBuilder,
                       const StructWithoutCopyOrMove &Value) {
     HBuilder.add(Value.I);
@@ -153,7 +153,7 @@ struct /* __attribute__((packed)) */ StructWithFastHash {
 
   // If possible, we want to hash both `I` and `C` in a single `update`
   // call for performance concerns.
-  template <typename HasherT, llvm::support::endianness Endianness>
+  template <typename HasherT, llvm::endianness Endianness>
   friend void addHash(llvm::HashBuilder<HasherT, Endianness> &HBuilder,
                       const StructWithFastHash &Value) {
     if (Endianness == llvm::endianness::native) {
@@ -177,7 +177,7 @@ struct CustomContainer {
     for (size_t I = 0; I != Size; ++I)
       Elements[I] = I;
   }
-  template <typename HasherT, llvm::support::endianness Endianness>
+  template <typename HasherT, llvm::endianness Endianness>
   friend void addHash(llvm::HashBuilder<HasherT, Endianness> &HBuilder,
                       const CustomContainer &Value) {
     if (Endianness == llvm::endianness::native) {
@@ -325,13 +325,11 @@ TEST(CustomHasher, CustomHasher) {
   };
 
   {
-    llvm::HashBuilder<SumHash, llvm::support::endianness::little> HBuilder(0,
-                                                                           1);
+    llvm::HashBuilder<SumHash, llvm::endianness::little> HBuilder(0, 1);
     EXPECT_EQ(HBuilder.add(0x02, 0x03, 0x400).getHasher().Hash, 0xa);
   }
   {
-    llvm::HashBuilder<SumHash, llvm::support::endianness::little> HBuilder(2,
-                                                                           3);
+    llvm::HashBuilder<SumHash, llvm::endianness::little> HBuilder(2, 3);
     EXPECT_EQ(HBuilder.add("ab", 'c').getHasher().Hash,
               static_cast<uint8_t>(/*seeds*/ 2 + 3 + /*range size*/ 2 +
                                    /*characters*/ 'a' + 'b' + 'c'));