diff --git a/llvm/include/llvm/Demangle/ItaniumDemangle.h b/llvm/include/llvm/Demangle/ItaniumDemangle.h
--- a/llvm/include/llvm/Demangle/ItaniumDemangle.h
+++ b/llvm/include/llvm/Demangle/ItaniumDemangle.h
@@ -221,6 +221,17 @@
   /// Visit the most-derived object corresponding to this object.
   template<typename Fn> void visit(Fn F) const;
 
+  /// Returns true if the tree rooted at this node is equivalent to
+  /// the tree rooted at the specified 'Root' node.
+  /// 
+  /// Equivalence of two nodes N1 and N2 is defined as:
+  /// 1. N1.getKind() == N2.getKind()
+  /// 2. N1 == N2 where '==' is defined by the
+  ///    kind of N1 and N2.
+  ///
+  /// Behaviour is undefined if 'Root == nullptr'.
+  bool equals(Node const* Root) const;
+
   // The following function is provided by all derived classes:
   //
   // Call F with arguments that, when passed to the constructor of this node,
@@ -331,6 +342,23 @@
       FirstElement = false;
     }
   }
+
+  friend bool operator==(NodeArray const& LHS, NodeArray const& RHS) {
+    if (LHS.size() != RHS.size())
+      return false;
+
+    auto** IT1 = LHS.begin();
+    auto** IT2 = RHS.begin();
+    for (; IT1 != LHS.end(); ++IT1, ++IT2)
+      if (!(*IT1)->equals(*IT2))
+        return false;
+
+    return true;
+  }
+
+  friend bool operator!=(NodeArray const& LHS, NodeArray const& RHS) {
+    return !(LHS == RHS);
+  }
 };
 
 struct NodeArrayNode : Node {
@@ -340,6 +368,14 @@
   template<typename Fn> void match(Fn F) const { F(Array); }
 
   void printLeft(OutputBuffer &OB) const override { Array.printWithComma(OB); }
+
+  friend bool operator==(NodeArrayNode const& LHS, NodeArrayNode const& RHS) {
+    return LHS.Array == RHS.Array;
+  }
+
+  friend bool operator!=(NodeArrayNode const& LHS, NodeArrayNode const& RHS) {
+    return !(LHS == RHS);
+  }
 };
 
 class DotSuffix final : public Node {
@@ -358,6 +394,14 @@
     OB += Suffix;
     OB += ")";
   }
+
+  friend bool operator==(DotSuffix const& LHS, DotSuffix const& RHS) {
+    return LHS.Suffix == RHS.Suffix && LHS.Prefix->equals(RHS.Prefix);
+  }
+
+  friend bool operator!=(DotSuffix const& LHS, DotSuffix const& RHS) {
+    return !(LHS == RHS);
+  }
 };
 
 class VendorExtQualType final : public Node {
@@ -382,6 +426,16 @@
     if (TA != nullptr)
       TA->print(OB);
   }
+
+  friend bool operator==(VendorExtQualType const& LHS, VendorExtQualType const& RHS) {
+    return LHS.Ext == RHS.Ext
+           && LHS.Ty->equals(RHS.Ty)
+           && LHS.TA->equals(RHS.TA);
+  }
+
+  friend bool operator!=(VendorExtQualType const& LHS, VendorExtQualType const& RHS) {
+    return !(LHS == RHS);
+  }
 };
 
 enum FunctionRefQual : unsigned char {
@@ -442,6 +496,11 @@
   }
 
   void printRight(OutputBuffer &OB) const override { Child->printRight(OB); }
+
+  friend bool operator==(QualType const& LHS, QualType const& RHS) {
+    return LHS.Quals == RHS.Quals
+           && LHS.Child->equals(RHS.Child);
+  }
 };
 
 class ConversionOperatorType final : public Node {
@@ -457,6 +516,11 @@
     OB += "operator ";
     Ty->print(OB);
   }
+
+  friend bool operator==(ConversionOperatorType const& LHS,
+                         ConversionOperatorType const& RHS) {
+    return LHS.Ty->equals(RHS.Ty);
+  }
 };
 
 class PostfixQualifiedType final : public Node {
@@ -473,6 +537,12 @@
     Ty->printLeft(OB);
     OB += Postfix;
   }
+
+  friend bool operator==(PostfixQualifiedType const& LHS,
+                         PostfixQualifiedType const& RHS) {
+    return LHS.Postfix == RHS.Postfix
+           && LHS.Ty->equals(RHS.Ty);
+  }
 };
 
 class NameType final : public Node {
@@ -487,6 +557,10 @@
   StringView getBaseName() const override { return Name; }
 
   void printLeft(OutputBuffer &OB) const override { OB += Name; }
+
+  friend bool operator==(NameType const& LHS, NameType const& RHS) {
+    return LHS.Name == RHS.Name;
+  }
 };
 
 class BitIntType final : public Node {
@@ -507,6 +581,11 @@
     Size->printAsOperand(OB);
     OB.printClose();
   }
+
+  friend bool operator==(BitIntType const& LHS, BitIntType const& RHS) {
+    return LHS.Signed == RHS.Signed
+           && LHS.Size->equals(RHS.Size);
+  }
 };
 
 class ElaboratedTypeSpefType : public Node {
@@ -523,6 +602,12 @@
     OB += ' ';
     Child->print(OB);
   }
+
+  friend bool operator==(ElaboratedTypeSpefType const& LHS,
+                         ElaboratedTypeSpefType const& RHS) {
+    return LHS.Kind == RHS.Kind
+           && LHS.Child->equals(RHS.Child);
+  }
 };
 
 struct AbiTagAttr : Node {
@@ -542,6 +627,11 @@
     OB += Tag;
     OB += "]";
   }
+
+  friend bool operator==(AbiTagAttr const& LHS, AbiTagAttr const& RHS) {
+    return LHS.Tag == RHS.Tag
+           && LHS.Base->equals(RHS.Base);
+  }
 };
 
 class EnableIfAttr : public Node {
@@ -557,6 +647,11 @@
     Conditions.printWithComma(OB);
     OB += ']';
   }
+
+  friend bool operator==(EnableIfAttr const& LHS,
+                         EnableIfAttr const& RHS) {
+    return LHS.Conditions == RHS.Conditions;
+  }
 };
 
 class ObjCProtoName : public Node {
@@ -582,6 +677,12 @@
     OB += Protocol;
     OB += ">";
   }
+
+  friend bool operator==(ObjCProtoName const& LHS,
+                         ObjCProtoName const& RHS) {
+    return LHS.Protocol == RHS.Protocol
+           && LHS.Ty->equals(RHS.Ty);
+  }
 };
 
 class PointerType final : public Node {
@@ -626,6 +727,10 @@
       Pointee->printRight(OB);
     }
   }
+
+  friend bool operator==(PointerType const& LHS, PointerType const& RHS) {
+    return LHS.Pointee->equals(RHS.Pointee);
+  }
 };
 
 enum class ReferenceKind {
@@ -708,6 +813,11 @@
       OB += ")";
     Collapsed.second->printRight(OB);
   }
+
+  friend bool operator==(ReferenceType const& LHS, ReferenceType const& RHS) {
+    return LHS.RK == RHS.RK
+           && LHS.Pointee->equals(RHS.Pointee);
+  }
 };
 
 class PointerToMemberType final : public Node {
@@ -740,6 +850,11 @@
       OB += ")";
     MemberType->printRight(OB);
   }
+
+  friend bool operator==(PointerToMemberType const& LHS, PointerToMemberType const& RHS) {
+    return LHS.ClassType->equals(RHS.ClassType)
+           && LHS.MemberType->equals(RHS.MemberType);
+  }
 };
 
 class ArrayType final : public Node {
@@ -769,6 +884,11 @@
     OB += "]";
     Base->printRight(OB);
   }
+
+  friend bool operator==(ArrayType const& LHS, ArrayType const& RHS) {
+    return LHS.Base->equals(RHS.Base)
+           && LHS.Dimension->equals(RHS.Dimension);
+  }
 };
 
 class FunctionType final : public Node {
@@ -829,6 +949,14 @@
       ExceptionSpec->print(OB);
     }
   }
+
+  friend bool operator==(FunctionType const& LHS, FunctionType const& RHS) {
+    return LHS.CVQuals == RHS.CVQuals
+           && LHS.RefQual == RHS.RefQual
+           && LHS.Params == RHS.Params
+           && LHS.Ret->equals(RHS.Ret)
+           && LHS.ExceptionSpec->equals(RHS.ExceptionSpec);
+  }
 };
 
 class NoexceptSpec : public Node {
@@ -844,6 +972,10 @@
     E->printAsOperand(OB);
     OB.printClose();
   }
+
+  friend bool operator==(NoexceptSpec const& LHS, NoexceptSpec const& RHS) {
+    return LHS.E->equals(RHS.E);
+  }
 };
 
 class DynamicExceptionSpec : public Node {
@@ -860,6 +992,11 @@
     Types.printWithComma(OB);
     OB.printClose();
   }
+
+  friend bool operator==(DynamicExceptionSpec const& LHS,
+                         DynamicExceptionSpec const& RHS) {
+    return LHS.Types == RHS.Types;
+  }
 };
 
 class FunctionEncoding final : public Node {
@@ -926,6 +1063,31 @@
     if (Attrs != nullptr)
       Attrs->print(OB);
   }
+
+  friend bool operator==(FunctionEncoding const& LHS,
+                         FunctionEncoding const& RHS) {
+    if (LHS.CVQuals != RHS.CVQuals)
+      return false;
+
+    if (LHS.RefQual != RHS.RefQual)
+      return false;
+
+    if (!!LHS.Ret != !!RHS.Ret)
+      return false;
+    
+    if (LHS.Ret)
+      if (!LHS.Ret->equals(RHS.Ret))
+          return false;
+
+    if (!!LHS.Attrs != !!RHS.Attrs)
+      return false;
+
+    if (LHS.Attrs)
+      if (!LHS.Attrs->equals(RHS.Attrs))
+        return false;
+
+    return LHS.Params == RHS.Params;
+  }
 };
 
 class LiteralOperator : public Node {
@@ -941,6 +1103,11 @@
     OB += "operator\"\" ";
     OpName->print(OB);
   }
+
+  friend bool operator==(LiteralOperator const& LHS,
+                         LiteralOperator const& RHS) {
+    return LHS.OpName->equals(RHS.OpName);
+  }
 };
 
 class SpecialName final : public Node {
@@ -957,6 +1124,12 @@
     OB += Special;
     Child->print(OB);
   }
+
+  friend bool operator==(SpecialName const& LHS,
+                         SpecialName const& RHS) {
+    return LHS.Special == RHS.Special
+           && LHS.Child->equals(RHS.Child);
+  }
 };
 
 class CtorVtableSpecialName final : public Node {
@@ -976,6 +1149,12 @@
     OB += "-in-";
     SecondType->print(OB);
   }
+
+  friend bool operator==(CtorVtableSpecialName const& LHS,
+                         CtorVtableSpecialName const& RHS) {
+    return LHS.FirstType->equals(RHS.FirstType)
+           && LHS.SecondType->equals(RHS.SecondType);
+  }
 };
 
 struct NestedName : Node {
@@ -994,6 +1173,12 @@
     OB += "::";
     Name->print(OB);
   }
+
+  friend bool operator==(NestedName const& LHS,
+                         NestedName const& RHS) {
+    return LHS.Qual->equals(RHS.Qual)
+           && LHS.Name->equals(RHS.Name);
+  }
 };
 
 struct ModuleName : Node {
@@ -1016,6 +1201,21 @@
       OB += IsPartition ? ':' : '.';
     Name->print(OB);
   }
+
+  friend bool operator==(ModuleName const& LHS,
+                         ModuleName const& RHS) {
+    if (LHS.IsPartition != RHS.IsPartition)
+      return false;
+
+    if (!!LHS.Parent != !!RHS.Parent)
+      return false;
+
+    if (LHS.Parent)
+      if (!LHS.Parent->equals(RHS.Parent))
+        return false;
+     
+    return LHS.Name->equals(RHS.Name);
+  }
 };
 
 struct ModuleEntity : Node {
@@ -1034,6 +1234,12 @@
     OB += '@';
     Module->print(OB);
   }
+
+  friend bool operator==(ModuleEntity const& LHS,
+                         ModuleEntity const& RHS) {
+    return LHS.Module->equals(RHS.Module)
+           && LHS.Name->equals(RHS.Name);
+  }
 };
 
 struct LocalName : Node {
@@ -1050,6 +1256,11 @@
     OB += "::";
     Entity->print(OB);
   }
+
+  friend bool operator==(LocalName const& LHS, LocalName const& RHS) {
+    return LHS.Encoding->equals(RHS.Encoding)
+           && LHS.Entity->equals(RHS.Entity);
+  }
 };
 
 class QualifiedName final : public Node {
@@ -1070,6 +1281,12 @@
     OB += "::";
     Name->print(OB);
   }
+
+  friend bool operator==(QualifiedName const& LHS,
+                         QualifiedName const& RHS) {
+    return LHS.Qualifier->equals(RHS.Qualifier)
+           && LHS.Name->equals(RHS.Name);
+  }
 };
 
 class VectorType final : public Node {
@@ -1092,6 +1309,12 @@
       Dimension->print(OB);
     OB += "]";
   }
+
+  friend bool operator==(VectorType const& LHS,
+                         VectorType const& RHS) {
+    return LHS.BaseType->equals(RHS.BaseType)
+           && LHS.Dimension->equals(RHS.Dimension);
+  }
 };
 
 class PixelVectorType final : public Node {
@@ -1109,6 +1332,11 @@
     Dimension->print(OB);
     OB += "]";
   }
+
+  friend bool operator==(PixelVectorType const& LHS,
+                         PixelVectorType const& RHS) {
+    return LHS.Dimension->equals(RHS.Dimension);
+  }
 };
 
 class BinaryFPType final : public Node {
@@ -1124,6 +1352,11 @@
     OB += "_Float";
     Dimension->print(OB);
   }
+
+  friend bool operator==(BinaryFPType const& LHS,
+                         BinaryFPType const& RHS) {
+    return LHS.Dimension->equals(RHS.Dimension);
+  }
 };
 
 enum class TemplateParamKind { Type, NonType, Template };
@@ -1159,6 +1392,12 @@
     if (Index > 0)
       OB << Index - 1;
   }
+
+  friend bool operator==(SyntheticTemplateParamName const& LHS,
+                         SyntheticTemplateParamName const& RHS) {
+    return LHS.Kind == RHS.Kind
+           && LHS.Index == RHS.Index;
+  }
 };
 
 /// A template type parameter declaration, 'typename T'.
@@ -1174,6 +1413,11 @@
   void printLeft(OutputBuffer &OB) const override { OB += "typename "; }
 
   void printRight(OutputBuffer &OB) const override { Name->print(OB); }
+
+  friend bool operator==(TypeTemplateParamDecl const& LHS,
+                         TypeTemplateParamDecl const& RHS) {
+    return LHS.Name->equals(RHS.Name);
+  }
 };
 
 /// A non-type template parameter declaration, 'int N'.
@@ -1197,6 +1441,12 @@
     Name->print(OB);
     Type->printRight(OB);
   }
+
+  friend bool operator==(NonTypeTemplateParamDecl const& LHS,
+                         NonTypeTemplateParamDecl const& RHS) {
+    return LHS.Name->equals(RHS.Name)
+           && LHS.Type->equals(RHS.Type);
+  }
 };
 
 /// A template template parameter declaration,
@@ -1220,6 +1470,12 @@
   }
 
   void printRight(OutputBuffer &OB) const override { Name->print(OB); }
+
+  friend bool operator==(TemplateTemplateParamDecl const& LHS,
+                         TemplateTemplateParamDecl const& RHS) {
+    return LHS.Name->equals(RHS.Name)
+           && LHS.Params == RHS.Params;
+  }
 };
 
 /// A template parameter pack declaration, 'typename ...T'.
@@ -1238,6 +1494,11 @@
   }
 
   void printRight(OutputBuffer &OB) const override { Param->printRight(OB); }
+
+  friend bool operator==(TemplateParamPackDecl const& LHS,
+                         TemplateParamPackDecl const& RHS) {
+    return LHS.Param->equals(RHS.Param);
+  }
 };
 
 /// An unexpanded parameter pack (either in the expression or type context). If
@@ -1312,6 +1573,11 @@
     if (Idx < Data.size())
       Data[Idx]->printRight(OB);
   }
+
+  friend bool operator==(ParameterPack const& LHS,
+                         ParameterPack const& RHS) {
+    return LHS.Data == RHS.Data;
+  }
 };
 
 /// A variadic template argument. This node represents an occurrence of
@@ -1332,6 +1598,11 @@
   void printLeft(OutputBuffer &OB) const override {
     Elements.printWithComma(OB);
   }
+
+  friend bool operator==(TemplateArgumentPack const& LHS,
+                         TemplateArgumentPack const& RHS) {
+    return LHS.Elements == RHS.Elements;
+  }
 };
 
 /// A pack expansion. Below this node, there are some unexpanded ParameterPacks
@@ -1378,6 +1649,11 @@
       Child->print(OB);
     }
   }
+
+  friend bool operator==(ParameterPackExpansion const& LHS,
+                         ParameterPackExpansion const& RHS) {
+    return LHS.Child->equals(RHS.Child);
+  }
 };
 
 class TemplateArgs final : public Node {
@@ -1396,6 +1672,11 @@
     Params.printWithComma(OB);
     OB += ">";
   }
+
+  friend bool operator==(TemplateArgs const& LHS,
+                         TemplateArgs const& RHS) {
+    return LHS.Params == RHS.Params;
+  }
 };
 
 /// A forward-reference to a template argument that was not known at the point
@@ -1426,6 +1707,22 @@
   // out if more than one print* function is active.
   mutable bool Printing = false;
 
+  friend bool operator==(ForwardTemplateReference const& LHS,
+                         ForwardTemplateReference const& RHS) {
+    if (LHS.Index != RHS.Index)
+      return false;
+
+    if (!!LHS.Ref != !!RHS.Ref)
+      return false;
+
+    if (LHS.Ref)
+      if (!LHS.Ref->equals(RHS.Ref))
+        return false;
+
+    // Ignore 'Printing' member
+    return true;
+  }
+
   ForwardTemplateReference(size_t Index_)
       : Node(KForwardTemplateReference, Cache::Unknown, Cache::Unknown,
              Cache::Unknown),
@@ -1491,6 +1788,12 @@
     Name->print(OB);
     TemplateArgs->print(OB);
   }
+
+  friend bool operator==(NameWithTemplateArgs const& LHS,
+                         NameWithTemplateArgs const& RHS) {
+    return LHS.Name->equals(RHS.Name)
+           && LHS.TemplateArgs->equals(RHS.TemplateArgs);
+  }
 };
 
 class GlobalQualifiedName final : public Node {
@@ -1508,6 +1811,11 @@
     OB += "::";
     Child->print(OB);
   }
+
+  friend bool operator==(GlobalQualifiedName const& LHS,
+                         GlobalQualifiedName const& RHS) {
+    return LHS.Child->equals(RHS.Child);
+  }
 };
 
 enum class SpecialSubKind {
@@ -1566,6 +1874,11 @@
       OB << ">";
     }
   }
+
+  friend bool operator==(ExpandedSpecialSubstitution const& LHS,
+                         ExpandedSpecialSubstitution const& RHS) {
+    return LHS.SSK == RHS.SSK;
+  }
 };
 
 class SpecialSubstitution final : public ExpandedSpecialSubstitution {
@@ -1611,6 +1924,13 @@
       OB += "~";
     OB += Basename->getBaseName();
   }
+
+  friend bool operator==(CtorDtorName const& LHS,
+                         CtorDtorName const& RHS) {
+    return LHS.IsDtor == RHS.IsDtor
+           && LHS.Variant == RHS.Variant
+           && LHS.Basename->equals(RHS.Basename);
+  }
 };
 
 class DtorName : public Node {
@@ -1625,6 +1945,11 @@
     OB += "~";
     Base->printLeft(OB);
   }
+
+  friend bool operator==(DtorName const& LHS,
+                         DtorName const& RHS) {
+    return LHS.Base->equals(RHS.Base);
+  }
 };
 
 class UnnamedTypeName : public Node {
@@ -1640,6 +1965,11 @@
     OB += Count;
     OB += "\'";
   }
+
+  friend bool operator==(UnnamedTypeName const& LHS,
+                         UnnamedTypeName const& RHS) {
+    return LHS.Count == RHS.Count;
+  }
 };
 
 class ClosureTypeName : public Node {
@@ -1675,6 +2005,13 @@
     OB += "\'";
     printDeclarator(OB);
   }
+
+  friend bool operator==(ClosureTypeName const& LHS,
+                         ClosureTypeName const& RHS) {
+    return LHS.TemplateParams == RHS.TemplateParams
+           && LHS.Params == RHS.Params
+           && LHS.Count == RHS.Count;
+  }
 };
 
 class StructuredBindingName : public Node {
@@ -1690,6 +2027,11 @@
     Bindings.printWithComma(OB);
     OB.printClose(']');
   }
+
+  friend bool operator==(StructuredBindingName const& LHS,
+                         StructuredBindingName const& RHS) {
+    return LHS.Bindings == RHS.Bindings;
+  }
 };
 
 // -- Expression Nodes --
@@ -1726,6 +2068,13 @@
     if (ParenAll)
       OB.printClose();
   }
+
+  friend bool operator==(BinaryExpr const& LHS,
+                         BinaryExpr const& RHS) {
+    return LHS.InfixOperator == RHS.InfixOperator
+           && LHS.LHS->equals(RHS.LHS)
+           && LHS.RHS->equals(RHS.RHS);
+  }
 };
 
 class ArraySubscriptExpr : public Node {
@@ -1746,6 +2095,12 @@
     Op2->printAsOperand(OB);
     OB.printClose(']');
   }
+
+  friend bool operator==(ArraySubscriptExpr const& LHS,
+                         ArraySubscriptExpr const& RHS) {
+    return LHS.Op1->equals(RHS.Op1)
+           && LHS.Op2->equals(RHS.Op2);
+  }
 };
 
 class PostfixExpr : public Node {
@@ -1764,6 +2119,12 @@
     Child->printAsOperand(OB, getPrecedence(), true);
     OB += Operator;
   }
+
+  friend bool operator==(PostfixExpr const& LHS,
+                         PostfixExpr const& RHS) {
+    return LHS.Operator == RHS.Operator
+           && LHS.Child->equals(RHS.Child);
+  }
 };
 
 class ConditionalExpr : public Node {
@@ -1787,6 +2148,13 @@
     OB += " : ";
     Else->printAsOperand(OB, Prec::Assign, true);
   }
+
+  friend bool operator==(ConditionalExpr const& LHS,
+                         ConditionalExpr const& RHS) {
+    return LHS.Cond->equals(RHS.Cond)
+           && LHS.Then->equals(RHS.Then)
+           && LHS.Else->equals(RHS.Else);
+  }
 };
 
 class MemberExpr : public Node {
@@ -1807,6 +2175,13 @@
     OB += Kind;
     RHS->printAsOperand(OB, getPrecedence(), false);
   }
+
+  friend bool operator==(MemberExpr const& LHS,
+                         MemberExpr const& RHS) {
+    return LHS.Kind == RHS.Kind
+           && LHS.LHS->equals(RHS.LHS)
+           && LHS.RHS->equals(RHS.RHS);
+  }
 };
 
 class SubobjectExpr : public Node {
@@ -1841,6 +2216,15 @@
     }
     OB += ">";
   }
+
+  friend bool operator==(SubobjectExpr const& LHS,
+                         SubobjectExpr const& RHS) {
+    return LHS.Offset == RHS.Offset
+           && LHS.OnePastTheEnd == RHS.OnePastTheEnd
+           && LHS.Type->equals(RHS.Type)
+           && LHS.SubExpr->equals(RHS.SubExpr)
+           && LHS.UnionSelectors == RHS.UnionSelectors;
+  }
 };
 
 class EnclosingExpr : public Node {
@@ -1864,6 +2248,13 @@
     OB.printClose();
     OB += Postfix;
   }
+
+  friend bool operator==(EnclosingExpr const& LHS,
+                         EnclosingExpr const& RHS) {
+    return LHS.Prefix == RHS.Prefix
+           && LHS.Postfix == RHS.Postfix
+           && LHS.Infix->equals(RHS.Infix);
+  }
 };
 
 class CastExpr : public Node {
@@ -1892,6 +2283,13 @@
     From->printAsOperand(OB);
     OB.printClose();
   }
+
+  friend bool operator==(CastExpr const& LHS,
+                         CastExpr const& RHS) {
+    return LHS.CastKind == RHS.CastKind
+           && LHS.To->equals(RHS.To)
+           && LHS.From->equals(RHS.From);
+  }
 };
 
 class SizeofParamPackExpr : public Node {
@@ -1910,6 +2308,11 @@
     PPE.printLeft(OB);
     OB.printClose();
   }
+
+  friend bool operator==(SizeofParamPackExpr const& LHS,
+                         SizeofParamPackExpr const& RHS) {
+    return LHS.Pack->equals(RHS.Pack);
+  }
 };
 
 class CallExpr : public Node {
@@ -1930,6 +2333,12 @@
     Args.printWithComma(OB);
     OB.printClose();
   }
+
+  friend bool operator==(CallExpr const& LHS,
+                         CallExpr const& RHS) {
+    return LHS.Callee->equals(RHS.Callee)
+           && LHS.Args == RHS.Args;
+  }
 };
 
 class NewExpr : public Node {
@@ -1968,6 +2377,15 @@
       OB.printClose();
     }
   }
+
+  friend bool operator==(NewExpr const& LHS,
+                         NewExpr const& RHS) {
+    return LHS.IsGlobal == RHS.IsGlobal
+           && LHS.IsArray == RHS.IsArray
+           && LHS.Type->equals(RHS.Type)
+           && LHS.ExprList == RHS.ExprList
+           && LHS.InitList == RHS.InitList;
+  }
 };
 
 class DeleteExpr : public Node {
@@ -1993,6 +2411,13 @@
     OB += ' ';
     Op->print(OB);
   }
+
+  friend bool operator==(DeleteExpr const& LHS,
+                         DeleteExpr const& RHS) {
+    return LHS.IsGlobal == RHS.IsGlobal
+           && LHS.IsArray == RHS.IsArray
+           && LHS.Op->equals(RHS.Op);
+  }
 };
 
 class PrefixExpr : public Node {
@@ -2011,6 +2436,12 @@
     OB += Prefix;
     Child->printAsOperand(OB, getPrecedence());
   }
+
+  friend bool operator==(PrefixExpr const& LHS,
+                         PrefixExpr const& RHS) {
+    return LHS.Prefix == RHS.Prefix
+           && LHS.Child->equals(RHS.Child);
+  }
 };
 
 class FunctionParam : public Node {
@@ -2025,6 +2456,11 @@
     OB += "fp";
     OB += Number;
   }
+
+  friend bool operator==(FunctionParam const& LHS,
+                         FunctionParam const& RHS) {
+    return LHS.Number == RHS.Number;
+  }
 };
 
 class ConversionExpr : public Node {
@@ -2047,6 +2483,12 @@
     Expressions.printWithComma(OB);
     OB.printClose();
   }
+
+  friend bool operator==(ConversionExpr const& LHS,
+                         ConversionExpr const& RHS) {
+    return LHS.Type->equals(RHS.Type)
+           && LHS.Expressions == RHS.Expressions;
+  }
 };
 
 class PointerToMemberConversionExpr : public Node {
@@ -2072,6 +2514,13 @@
     SubExpr->print(OB);
     OB.printClose();
   }
+
+  friend bool operator==(PointerToMemberConversionExpr const& LHS,
+                         PointerToMemberConversionExpr const& RHS) {
+    return LHS.Offset == RHS.Offset
+           && LHS.Type->equals(RHS.Type)
+           && LHS.SubExpr->equals(RHS.SubExpr);
+  }
 };
 
 class InitListExpr : public Node {
@@ -2090,6 +2539,18 @@
     Inits.printWithComma(OB);
     OB += '}';
   }
+
+  friend bool operator==(InitListExpr const& LHS,
+                         InitListExpr const& RHS) {
+    if (!!LHS.Ty != !!RHS.Ty)
+      return false;
+
+    if (LHS.Ty)
+      if (!LHS.Ty->equals(RHS.Ty))
+        return false;
+
+    return LHS.Inits == RHS.Inits;
+  }
 };
 
 class BracedExpr : public Node {
@@ -2115,6 +2576,13 @@
       OB += " = ";
     Init->print(OB);
   }
+
+  friend bool operator==(BracedExpr const& LHS,
+                         BracedExpr const& RHS) {
+    return LHS.IsArray == RHS.IsArray
+           && LHS.Elem->equals(RHS.Elem)
+           && LHS.Init->equals(RHS.Init);
+  }
 };
 
 class BracedRangeExpr : public Node {
@@ -2137,6 +2605,13 @@
       OB += " = ";
     Init->print(OB);
   }
+
+  friend bool operator==(BracedRangeExpr const& LHS,
+                         BracedRangeExpr const& RHS) {
+    return LHS.First->equals(RHS.First)
+           && LHS.Last->equals(RHS.Last)
+           && LHS.Init->equals(RHS.Init);
+  }
 };
 
 class FoldExpr : public Node {
@@ -2184,6 +2659,22 @@
     }
     OB.printClose();
   }
+
+  friend bool operator==(FoldExpr const& LHS,
+                         FoldExpr const& RHS) {
+    if (LHS.IsLeftFold != RHS.IsLeftFold
+        || LHS.OperatorName == RHS.OperatorName)
+      return false;
+
+    if (!!LHS.Pack != !!RHS.Pack)
+      return false;
+
+    if (LHS.Pack)
+      if (!LHS.Pack->equals(RHS.Pack))
+        return false;
+
+    return LHS.Init->equals(RHS.Init);
+  }
 };
 
 class ThrowExpr : public Node {
@@ -2198,6 +2689,11 @@
     OB += "throw ";
     Op->print(OB);
   }
+
+  friend bool operator==(ThrowExpr const& LHS,
+                         ThrowExpr const& RHS) {
+    return LHS.Op->equals(RHS.Op);
+  }
 };
 
 class BoolExpr : public Node {
@@ -2211,6 +2707,11 @@
   void printLeft(OutputBuffer &OB) const override {
     OB += Value ? StringView("true") : StringView("false");
   }
+
+  friend bool operator==(BoolExpr const& LHS,
+                         BoolExpr const& RHS) {
+    return LHS.Value == RHS.Value;
+  }
 };
 
 class StringLiteral : public Node {
@@ -2226,6 +2727,11 @@
     Type->print(OB);
     OB += ">\"";
   }
+
+  friend bool operator==(StringLiteral const& LHS,
+                         StringLiteral const& RHS) {
+    return LHS.Type->equals(RHS.Type);
+  }
 };
 
 class LambdaExpr : public Node {
@@ -2242,6 +2748,11 @@
       static_cast<const ClosureTypeName *>(Type)->printDeclarator(OB);
     OB += "{...}";
   }
+
+  friend bool operator==(LambdaExpr const& LHS,
+                         LambdaExpr const& RHS) {
+    return LHS.Type->equals(RHS.Type);
+  }
 };
 
 class EnumLiteral : public Node {
@@ -2265,6 +2776,12 @@
     else
       OB << Integer;
   }
+
+  friend bool operator==(EnumLiteral const& LHS,
+                         EnumLiteral const& RHS) {
+    return LHS.Integer == RHS.Integer
+           && LHS.Ty->equals(RHS.Ty);
+  }
 };
 
 class IntegerLiteral : public Node {
@@ -2293,6 +2810,12 @@
     if (Type.size() <= 3)
       OB += Type;
   }
+
+  friend bool operator==(IntegerLiteral const& LHS,
+                         IntegerLiteral const& RHS) {
+    return LHS.Type == RHS.Type
+           && LHS.Value == RHS.Value;
+  }
 };
 
 template <class Float> struct FloatData;
@@ -2350,6 +2873,11 @@
       OB += StringView(num, num + n);
     }
   }
+
+  friend bool operator==(FloatLiteralImpl<Float> const& LHS,
+                         FloatLiteralImpl<Float> const& RHS) {
+    return LHS.Contents == RHS.Contents;
+  }
 };
 
 using FloatLiteral = FloatLiteralImpl<float>;
diff --git a/llvm/lib/Demangle/ItaniumDemangle.cpp b/llvm/lib/Demangle/ItaniumDemangle.cpp
--- a/llvm/lib/Demangle/ItaniumDemangle.cpp
+++ b/llvm/lib/Demangle/ItaniumDemangle.cpp
@@ -58,6 +58,22 @@
   return first;
 }
 
+bool Node::equals(Node const* Other) const {
+  assert(Other != nullptr);
+
+  if (K != Other->getKind())
+    return false;
+
+  switch (K) {
+#define NODE(X)                                                                \
+  case K##X:                                                                   \
+    return *static_cast<const X *>(this)  == *static_cast<const X *>(Other);
+#include "llvm/Demangle/ItaniumNodes.def"
+  }
+  assert(0 && "unknown mangling node kind");
+}
+
+
 #ifndef NDEBUG
 namespace {
 struct DumpVisitor {
diff --git a/llvm/unittests/Demangle/ItaniumDemangleTest.cpp b/llvm/unittests/Demangle/ItaniumDemangleTest.cpp
--- a/llvm/unittests/Demangle/ItaniumDemangleTest.cpp
+++ b/llvm/unittests/Demangle/ItaniumDemangleTest.cpp
@@ -7,32 +7,19 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Demangle/ItaniumDemangle.h"
+#include "ItaniumDemangleTestUtils.h"
+#include "llvm/IR/Argument.h"
 #include "llvm/Support/Allocator.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include <algorithm>
 #include <cstdlib>
+#include <iterator>
 #include <vector>
 
 using namespace llvm;
 using namespace llvm::itanium_demangle;
-
-namespace {
-class TestAllocator {
-  BumpPtrAllocator Alloc;
-
-public:
-  void reset() { Alloc.Reset(); }
-
-  template <typename T, typename... Args> T *makeNode(Args &&... args) {
-    return new (Alloc.Allocate(sizeof(T), alignof(T)))
-        T(std::forward<Args>(args)...);
-  }
-
-  void *allocateNodeArray(size_t sz) {
-    return Alloc.Allocate(sizeof(Node *) * sz, alignof(Node *));
-  }
-};
-} // namespace
+using namespace llvm::itanium_demangle::test_utils;
 
 namespace NodeMatcher {
 // Make sure the node matchers provide constructor parameters. This is a
@@ -113,3 +100,162 @@
   ASSERT_NE(nullptr, Parser.parse());
   EXPECT_THAT(Parser.Types, testing::ElementsAre("_Float16", "A", "_Float16"));
 }
+
+TEST(ItaniumDemangle, Equality_NodeArray) {
+  ManglingNodeCreator Creator;
+
+  // Test empty NodeArray equality
+  std::vector<Node *> LHS;
+  std::vector<Node *> RHS;
+
+  // Empty == Empty
+  ASSERT_EQ(Creator.makeNodeArray(LHS.cbegin(), LHS.cend()),
+            Creator.makeNodeArray(RHS.cbegin(), RHS.cend()));
+
+  RHS.push_back(Creator.makeReferenceType(Qualifiers::QualNone, "test",
+                                          ReferenceKind::RValue));
+
+  // Empty vs. non-empty
+  ASSERT_NE(Creator.makeNodeArray(LHS.cbegin(), LHS.cend()),
+            Creator.makeNodeArray(RHS.cbegin(), RHS.cend()));
+
+  LHS.push_back(Creator.makeReferenceType(Qualifiers::QualNone, "test",
+                                          ReferenceKind::RValue));
+
+  // Equal single nodes
+  ASSERT_EQ(Creator.makeNodeArray(LHS.cbegin(), LHS.cend()),
+            Creator.makeNodeArray(RHS.cbegin(), RHS.cend()));
+
+  LHS.push_back(Creator.makeReferenceType(Qualifiers::QualNone, "test",
+                                          ReferenceKind::LValue));
+  RHS.push_back(Creator.makeReferenceType(Qualifiers::QualRestrict, "test",
+                                          ReferenceKind::RValue));
+
+  // Non-equal second node
+  ASSERT_NE(Creator.makeNodeArray(LHS.cbegin(), LHS.cend()),
+            Creator.makeNodeArray(RHS.cbegin(), RHS.cend()));
+}
+
+TEST(ItaniumDemangle, Equality_QualType) {
+  ManglingNodeCreator Creator;
+
+  {
+    // Same qualifiers and name
+    Node const *Q1 = Creator.makeQualType("Test", Qualifiers::QualVolatile);
+    Node const *Q2 = Creator.makeQualType("Test", Qualifiers::QualVolatile);
+    ASSERT_TRUE(test_utils::compareNodes(Q1, Q2));
+  }
+
+  {
+    // Different qualifiers
+    Node const *Q1 = Creator.makeQualType("Test", Qualifiers::QualNone);
+    Node const *Q2 = Creator.makeQualType("Test", Qualifiers::QualRestrict);
+    ASSERT_FALSE(test_utils::compareNodes(Q1, Q2));
+  }
+
+  {
+    // Different name
+    Node const *Q1 = Creator.makeQualType("Test", Qualifiers::QualNone);
+    Node const *Q2 = Creator.makeQualType("", Qualifiers::QualNone);
+    ASSERT_FALSE(test_utils::compareNodes(Q1, Q2));
+  }
+}
+
+TEST(ItaniumDemangle, Equality_NameType) {
+  ManglingNodeCreator Creator;
+
+  {
+    // Both empty
+    Node const *Q1 = Creator.makeNameType("");
+    Node const *Q2 = Creator.makeNameType("");
+    ASSERT_TRUE(test_utils::compareNodes(Q1, Q2));
+  }
+
+  {
+    // Both non-empty
+    Node const *Q1 = Creator.makeNameType("test");
+    Node const *Q2 = Creator.makeNameType("test");
+    ASSERT_TRUE(test_utils::compareNodes(Q1, Q2));
+  }
+
+  {
+    // Not equal
+    Node const *Q1 = Creator.makeNameType("test");
+    Node const *Q2 = Creator.makeNameType("tes");
+    ASSERT_FALSE(test_utils::compareNodes(Q1, Q2));
+  }
+}
+
+TEST(ItaniumDemangle, Equality_ReferenceType) {
+  ManglingNodeCreator Creator;
+
+  {
+    // Same type
+    Node const *Q1 = Creator.makeReferenceType(Qualifiers::QualVolatile, "Test",
+                                               ReferenceKind::LValue);
+    Node const *Q2 = Creator.makeReferenceType(Qualifiers::QualVolatile, "Test",
+                                               ReferenceKind::LValue);
+    ASSERT_TRUE(test_utils::compareNodes(Q1, Q2));
+  }
+
+  {
+    // Different name
+    Node const *Q1 = Creator.makeReferenceType(Qualifiers::QualVolatile, "Test",
+                                               ReferenceKind::LValue);
+    Node const *Q2 = Creator.makeReferenceType(Qualifiers::QualVolatile, "Tes",
+                                               ReferenceKind::LValue);
+    ASSERT_FALSE(test_utils::compareNodes(Q1, Q2));
+  }
+
+  {
+    // Different CV-qualifiers
+    Node const *Q1 = Creator.makeReferenceType(Qualifiers::QualVolatile, "Test",
+                                               ReferenceKind::LValue);
+    Node const *Q2 = Creator.makeReferenceType(Qualifiers::QualRestrict, "Test",
+                                               ReferenceKind::LValue);
+    ASSERT_FALSE(test_utils::compareNodes(Q1, Q2));
+  }
+
+  {
+    // Different ref-qualifiers
+    Node const *Q1 = Creator.makeReferenceType(Qualifiers::QualVolatile, "Test",
+                                               ReferenceKind::LValue);
+    Node const *Q2 = Creator.makeReferenceType(Qualifiers::QualVolatile, "Test",
+                                               ReferenceKind::RValue);
+    ASSERT_FALSE(test_utils::compareNodes(Q1, Q2));
+  }
+}
+
+TEST(ItaniumDemangle, Equality_TemplateArgs) {
+  ManglingNodeCreator Creator;
+
+  std::vector<Node *> LHS;
+  std::vector<Node *> RHS;
+
+  {
+    // Both empty
+    Node const *Q1 = Creator.makeTemplateArgs(LHS);
+    Node const *Q2 = Creator.makeTemplateArgs(RHS);
+    ASSERT_TRUE(test_utils::compareNodes(Q1, Q2));
+  }
+
+  LHS.push_back(Creator.makeNameType("test"));
+  RHS.push_back(Creator.makeNameType("test"));
+
+  {
+    // Both equal
+    Node const *Q1 = Creator.makeTemplateArgs(LHS);
+    Node const *Q2 = Creator.makeTemplateArgs(RHS);
+    ASSERT_TRUE(test_utils::compareNodes(Q1, Q2));
+  }
+
+  LHS.push_back(Creator.makeNameType("foo"));
+  RHS.push_back(Creator.makeNameType("bar"));
+
+  {
+    // Not equal anymore
+    Node const *Q1 = Creator.makeTemplateArgs(LHS);
+    Node const *Q2 = Creator.makeTemplateArgs(RHS);
+    ASSERT_FALSE(test_utils::compareNodes(Q1, Q2));
+  }
+}
diff --git a/llvm/unittests/Demangle/ItaniumDemangleTestUtils.h b/llvm/unittests/Demangle/ItaniumDemangleTestUtils.h
new file mode 100644
--- /dev/null
+++ b/llvm/unittests/Demangle/ItaniumDemangleTestUtils.h
@@ -0,0 +1,77 @@
+//===------------------ ItaniumDemangleTestUtils.h ------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEMANGLE_ITANIUMDEMANGLE_TEST_UTILS_H
+#define LLVM_DEMANGLE_ITANIUMDEMANGLE_TEST_UTILS_H
+
+#include "llvm/Demangle/Demangle.h"
+#include "llvm/Demangle/ItaniumDemangle.h"
+#include "llvm/Demangle/StringView.h"
+#include "llvm/Support/Allocator.h"
+
+#include <vector>
+
+namespace llvm::itanium_demangle::test_utils {
+
+class TestAllocator {
+  BumpPtrAllocator Alloc;
+
+public:
+  void reset() { Alloc.Reset(); }
+
+  template <typename T, typename... Args> T *makeNode(Args &&...args) {
+    return new (Alloc.Allocate(sizeof(T), alignof(T)))
+        T(std::forward<Args>(args)...);
+  }
+
+  void *allocateNodeArray(size_t sz) {
+    return Alloc.Allocate(sizeof(Node *) * sz, alignof(Node *));
+  }
+};
+
+struct ManglingNodeCreator
+    : AbstractManglingParser<ManglingNodeCreator, TestAllocator> {
+
+  ManglingNodeCreator() : AbstractManglingParser(nullptr, nullptr) {}
+
+  auto *makeNameType(StringView Type) { return make<NameType>(Type); }
+
+  auto *makeTemplateArgs(std::vector<Node *> const &Args) {
+    return make<TemplateArgs>(makeNodeArray(Args.cbegin(), Args.cend()));
+  }
+
+  auto *makeQualType(StringView VarName, Qualifiers Quals) {
+    return make<QualType>(makeNameType(VarName), Quals);
+  }
+
+  auto *makeReferenceType(Qualifiers Quals, StringView ArgName,
+                          ReferenceKind RefKind) {
+    return make<ReferenceType>(makeQualType(ArgName, Quals), RefKind);
+  }
+
+  auto *makeNameWithTemplateArgsNode(StringView FnName,
+                                     std::vector<Node *> const &Args) {
+    auto *TArgs = makeTemplateArgs(Args);
+    return make<NameWithTemplateArgs>(makeNameType(FnName), TArgs);
+  }
+
+  auto *makeFunctionEncoding(StringView FnName, NodeArray Params,
+                             Qualifiers CVQuals, FunctionRefQual RefQual) {
+    auto const *NameNode = makeNameType(FnName);
+    return make<FunctionEncoding>(nullptr, NameNode, Params, nullptr, CVQuals,
+                                  RefQual);
+  }
+};
+
+inline bool compareNodes(Node const *LHS, Node const *RHS) {
+  return LHS && RHS && LHS->equals(RHS);
+}
+
+} // namespace llvm::itanium_demangle::test_utils
+
+#endif // LLVM_DEMANGLE_ITANIUMDEMANGLE_TEST_UTILS_H