diff --git a/linux-x64/clang/include/llvm/Demangle/ItaniumDemangle.h b/linux-x64/clang/include/llvm/Demangle/ItaniumDemangle.h
index df06aa6..aaccb27 100644
--- a/linux-x64/clang/include/llvm/Demangle/ItaniumDemangle.h
+++ b/linux-x64/clang/include/llvm/Demangle/ItaniumDemangle.h
@@ -89,6 +89,7 @@
     X(InitListExpr) \
     X(FoldExpr) \
     X(ThrowExpr) \
+    X(UUIDOfExpr) \
     X(BoolExpr) \
     X(IntegerCastExpr) \
     X(IntegerLiteral) \
@@ -1873,6 +1874,21 @@
   }
 };
 
+// MSVC __uuidof extension, generated by clang in -fms-extensions mode.
+class UUIDOfExpr : public Node {
+  Node *Operand;
+public:
+  UUIDOfExpr(Node *Operand_) : Node(KUUIDOfExpr), Operand(Operand_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Operand); }
+
+  void printLeft(OutputStream &S) const override {
+    S << "__uuidof(";
+    Operand->print(S);
+    S << ")";
+  }
+};
+
 class BoolExpr : public Node {
   bool Value;
 
@@ -2794,11 +2810,13 @@
 // <ctor-dtor-name> ::= C1  # complete object constructor
 //                  ::= C2  # base object constructor
 //                  ::= C3  # complete object allocating constructor
-//   extension      ::= C5    # ?
+//   extension      ::= C4  # gcc old-style "[unified]" constructor
+//   extension      ::= C5  # the COMDAT used for ctors
 //                  ::= D0  # deleting destructor
 //                  ::= D1  # complete object destructor
 //                  ::= D2  # base object destructor
-//   extension      ::= D5    # ?
+//   extension      ::= D4  # gcc old-style "[unified]" destructor
+//   extension      ::= D5  # the COMDAT used for dtors
 template <typename Derived, typename Alloc>
 Node *
 AbstractManglingParser<Derived, Alloc>::parseCtorDtorName(Node *&SoFar,
@@ -2821,7 +2839,8 @@
 
   if (consumeIf('C')) {
     bool IsInherited = consumeIf('I');
-    if (look() != '1' && look() != '2' && look() != '3' && look() != '5')
+    if (look() != '1' && look() != '2' && look() != '3' && look() != '4' &&
+        look() != '5')
       return nullptr;
     int Variant = look() - '0';
     ++First;
@@ -2830,15 +2849,15 @@
       if (getDerived().parseName(State) == nullptr)
         return nullptr;
     }
-    return make<CtorDtorName>(SoFar, false, Variant);
+    return make<CtorDtorName>(SoFar, /*IsDtor=*/false, Variant);
   }
 
-  if (look() == 'D' &&
-      (look(1) == '0' || look(1) == '1' || look(1) == '2' || look(1) == '5')) {
+  if (look() == 'D' && (look(1) == '0' || look(1) == '1' || look(1) == '2' ||
+                        look(1) == '4' || look(1) == '5')) {
     int Variant = look(1) - '0';
     First += 2;
     if (State) State->CtorDtorConversion = true;
-    return make<CtorDtorName>(SoFar, true, Variant);
+    return make<CtorDtorName>(SoFar, /*IsDtor=*/true, Variant);
   }
 
   return nullptr;
@@ -3573,7 +3592,11 @@
     StringView Res = parseBareSourceName();
     if (Res.empty())
       return nullptr;
-    return make<NameType>(Res);
+    // Typically, <builtin-type>s are not considered substitution candidates,
+    // but the exception to that exception is vendor extended types (Itanium C++
+    // ABI 5.9.1).
+    Result = make<NameType>(Res);
+    break;
   }
   case 'D':
     switch (look(1)) {
@@ -3601,6 +3624,10 @@
     case 's':
       First += 2;
       return make<NameType>("char16_t");
+    //                ::= Du   # char8_t (C++2a, not yet in the Itanium spec)
+    case 'u':
+      First += 2;
+      return make<NameType>("char8_t");
     //                ::= Da   # auto (in dependent new-expressions)
     case 'a':
       First += 2;
@@ -4642,6 +4669,21 @@
   case '9':
     return getDerived().parseUnresolvedName();
   }
+
+  if (consumeIf("u8__uuidoft")) {
+    Node *Ty = getDerived().parseType();
+    if (!Ty)
+      return nullptr;
+    return make<UUIDOfExpr>(Ty);
+  }
+
+  if (consumeIf("u8__uuidofz")) {
+    Node *Ex = getDerived().parseExpr();
+    if (!Ex)
+      return nullptr;
+    return make<UUIDOfExpr>(Ex);
+  }
+
   return nullptr;
 }
 
diff --git a/linux-x64/clang/include/llvm/Demangle/MicrosoftDemangle.h b/linux-x64/clang/include/llvm/Demangle/MicrosoftDemangle.h
index a23e327..382e794 100644
--- a/linux-x64/clang/include/llvm/Demangle/MicrosoftDemangle.h
+++ b/linux-x64/clang/include/llvm/Demangle/MicrosoftDemangle.h
@@ -55,24 +55,21 @@
     }
   }
 
-  char *allocUnalignedBuffer(size_t Length) {
-    uint8_t *Buf = Head->Buf + Head->Used;
+  char *allocUnalignedBuffer(size_t Size) {
+    assert(Head && Head->Buf);
 
-    Head->Used += Length;
-    if (Head->Used > Head->Capacity) {
-      // It's possible we need a buffer which is larger than our default unit
-      // size, so we need to be careful to add a node with capacity that is at
-      // least as large as what we need.
-      addNode(std::max(AllocUnit, Length));
-      Head->Used = Length;
-      Buf = Head->Buf;
-    }
+    uint8_t *P = Head->Buf + Head->Used;
 
-    return reinterpret_cast<char *>(Buf);
+    Head->Used += Size;
+    if (Head->Used <= Head->Capacity)
+      return reinterpret_cast<char *>(P);
+
+    addNode(std::max(AllocUnit, Size));
+    Head->Used = Size;
+    return reinterpret_cast<char *>(Head->Buf);
   }
 
   template <typename T, typename... Args> T *allocArray(size_t Count) {
-
     size_t Size = Count * sizeof(T);
     assert(Head && Head->Buf);
 
@@ -83,17 +80,16 @@
     size_t Adjustment = AlignedP - P;
 
     Head->Used += Size + Adjustment;
-    if (Head->Used < Head->Capacity)
+    if (Head->Used <= Head->Capacity)
       return new (PP) T[Count]();
 
-    addNode(AllocUnit);
+    addNode(std::max(AllocUnit, Size));
     Head->Used = Size;
     return new (Head->Buf) T[Count]();
   }
 
   template <typename T, typename... Args> T *alloc(Args &&... ConstructorArgs) {
-
-    size_t Size = sizeof(T);
+    constexpr size_t Size = sizeof(T);
     assert(Head && Head->Buf);
 
     size_t P = (size_t)Head->Buf + Head->Used;
@@ -103,9 +99,10 @@
     size_t Adjustment = AlignedP - P;
 
     Head->Used += Size + Adjustment;
-    if (Head->Used < Head->Capacity)
+    if (Head->Used <= Head->Capacity)
       return new (PP) T(std::forward<Args>(ConstructorArgs)...);
 
+    static_assert(Size < AllocUnit, "");
     addNode(AllocUnit);
     Head->Used = Size;
     return new (Head->Buf) T(std::forward<Args>(ConstructorArgs)...);
@@ -159,6 +156,8 @@
 private:
   SymbolNode *demangleEncodedSymbol(StringView &MangledName,
                                     QualifiedNameNode *QN);
+  SymbolNode *demangleDeclarator(StringView &MangledName);
+  SymbolNode *demangleMD5Name(StringView &MangledName);
 
   VariableSymbolNode *demangleVariableEncoding(StringView &MangledName,
                                                StorageClass SC);
@@ -178,8 +177,9 @@
 
   ArrayTypeNode *demangleArrayType(StringView &MangledName);
 
+  NodeArrayNode *demangleFunctionParameterList(StringView &MangledName,
+                                               bool &IsVariadic);
   NodeArrayNode *demangleTemplateParameterList(StringView &MangledName);
-  NodeArrayNode *demangleFunctionParameterList(StringView &MangledName);
 
   std::pair<uint64_t, bool> demangleNumber(StringView &MangledName);
   uint64_t demangleUnsigned(StringView &MangledName);
@@ -206,6 +206,8 @@
   NamedIdentifierNode *demangleBackRefName(StringView &MangledName);
   IdentifierNode *demangleTemplateInstantiationName(StringView &MangledName,
                                                     NameBackrefBehavior NBB);
+  IntrinsicFunctionKind
+  translateIntrinsicFunctionCode(char CH, FunctionIdentifierCodeGroup Group);
   IdentifierNode *demangleFunctionIdentifierCode(StringView &MangledName);
   IdentifierNode *
   demangleFunctionIdentifierCode(StringView &MangledName,
@@ -222,7 +224,7 @@
   demangleSpecialTableSymbolNode(StringView &MangledName,
                                  SpecialIntrinsicKind SIK);
   LocalStaticGuardVariableNode *
-  demangleLocalStaticGuard(StringView &MangledName);
+  demangleLocalStaticGuard(StringView &MangledName, bool IsThread);
   VariableSymbolNode *demangleUntypedVariable(ArenaAllocator &Arena,
                                               StringView &MangledName,
                                               StringView VariableName);
diff --git a/linux-x64/clang/include/llvm/Demangle/MicrosoftDemangleNodes.h b/linux-x64/clang/include/llvm/Demangle/MicrosoftDemangleNodes.h
index b478418..da9d9d5 100644
--- a/linux-x64/clang/include/llvm/Demangle/MicrosoftDemangleNodes.h
+++ b/linux-x64/clang/include/llvm/Demangle/MicrosoftDemangleNodes.h
@@ -82,6 +82,7 @@
   Char,
   Schar,
   Uchar,
+  Char8,
   Char16,
   Char32,
   Short,
@@ -170,8 +171,8 @@
   VectorCopyCtorIter,         // ?__G vector copy constructor iterator
   VectorVbaseCopyCtorIter,    // ?__H vector vbase copy constructor iterator
   ManVectorVbaseCopyCtorIter, // ?__I managed vector vbase copy constructor
-  CoAwait,                    // ?__L co_await
-  Spaceship,                  // operator<=>
+  CoAwait,                    // ?__L operator co_await
+  Spaceship,                  // ?__M operator<=>
   MaxIntrinsic
 };
 
@@ -343,7 +344,7 @@
   // Function parameters
   NodeArrayNode *Params = nullptr;
 
-  // True if the function type is noexcept
+  // True if the function type is noexcept.
   bool IsNoexcept = false;
 };
 
@@ -408,6 +409,7 @@
 
   void output(OutputStream &OS, OutputFlags Flags) const override;
 
+  bool IsThread = false;
   uint32_t ScopeIndex = 0;
 };
 
@@ -513,7 +515,7 @@
 
   void output(OutputStream &OS, OutputFlags Flags, StringView Separator) const;
 
-  Node **Nodes = 0;
+  Node **Nodes = nullptr;
   size_t Count = 0;
 };