diff --git a/libcxxabi/src/demangle/ItaniumDemangle.h b/libcxxabi/src/demangle/ItaniumDemangle.h
index 6fdfe38bd0f1f..2336b84da293b 100644
--- a/libcxxabi/src/demangle/ItaniumDemangle.h
+++ b/libcxxabi/src/demangle/ItaniumDemangle.h
@@ -534,6 +534,23 @@ class ElaboratedTypeSpefType : public Node {
   }
 };
 
+class TransformedType : public Node {
+  std::string_view Transform;
+  Node *BaseType;
+public:
+  TransformedType(std::string_view Transform_, Node *BaseType_)
+      : Node(KTransformedType), Transform(Transform_), BaseType(BaseType_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Transform, BaseType); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Transform;
+    OB += '(';
+    BaseType->print(OB);
+    OB += ')';
+  }
+};
+
 struct AbiTagAttr : Node {
   Node *Base;
   std::string_view Tag;
@@ -4125,7 +4142,15 @@ Node *AbstractManglingParser<Derived, Alloc>::parseType() {
     // 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);
+    if (consumeIf('I')) {
+      Node *BaseType = parseType();
+      if (BaseType == nullptr)
+        return nullptr;
+      if (!consumeIf('E'))
+        return nullptr;
+      Result = make<TransformedType>(Res, BaseType);
+    } else
+      Result = make<NameType>(Res);
     break;
   }
   case 'D':
diff --git a/libcxxabi/src/demangle/ItaniumNodes.def b/libcxxabi/src/demangle/ItaniumNodes.def
index 74dc7097c1b30..e27c111de3389 100644
--- a/libcxxabi/src/demangle/ItaniumNodes.def
+++ b/libcxxabi/src/demangle/ItaniumNodes.def
@@ -19,6 +19,7 @@ NODE(QualType)
 NODE(ConversionOperatorType)
 NODE(PostfixQualifiedType)
 NODE(ElaboratedTypeSpefType)
+NODE(TransformedType)
 NODE(NameType)
 NODE(AbiTagAttr)
 NODE(EnableIfAttr)
diff --git a/libcxxabi/test/test_demangle.pass.cpp b/libcxxabi/test/test_demangle.pass.cpp
index 47cc29b2430e7..df7bedc73c289 100644
--- a/libcxxabi/test/test_demangle.pass.cpp
+++ b/libcxxabi/test/test_demangle.pass.cpp
@@ -30161,6 +30161,15 @@ const char* cases[][2] =
      " std::allocator<char>>::basic_string()"},
     {"_ZN1SB8ctor_tagC2Ev", "S[abi:ctor_tag]::S()"},
     {"_ZN1SB8ctor_tagD2Ev", "S[abi:ctor_tag]::~S()"},
+
+    // clang builtin type transform
+    {"_Z2f5IiEvu22__add_lvalue_referenceIT_E", "void f5<int>(__add_lvalue_reference(int))"},
+    {"_Z2f5IiEvu13__add_pointerIT_E", "void f5<int>(__add_pointer(int))"},
+    {"_Z2f5IiEvu7__decayIT_E", "void f5<int>(__decay(int))"},
+    {"_Z2f5IjEvu13__make_signedIT_E", "void f5<unsigned int>(__make_signed(unsigned int))"},
+    {"_Z2f5IKiEvu14__remove_constIT_E", "void f5<int const>(__remove_const(int const))"},
+    {"_Z2f5IPiEvu16__remove_pointerIT_E", "void f5<int*>(__remove_pointer(int*))"},
+    {"_Z2f5IiEvu14__remove_cvrefIT_E", "void f5<int>(__remove_cvref(int))"},
 };
 
 const unsigned N = sizeof(cases) / sizeof(cases[0]);
diff --git a/llvm/include/llvm/Demangle/ItaniumDemangle.h b/llvm/include/llvm/Demangle/ItaniumDemangle.h
index 52105bfeca5b7..f68c37258ce09 100644
--- a/llvm/include/llvm/Demangle/ItaniumDemangle.h
+++ b/llvm/include/llvm/Demangle/ItaniumDemangle.h
@@ -533,6 +533,23 @@ class ElaboratedTypeSpefType : public Node {
   }
 };
 
+class TransformedType : public Node {
+  std::string_view Transform;
+  Node *BaseType;
+public:
+  TransformedType(std::string_view Transform_, Node *BaseType_)
+      : Node(KTransformedType), Transform(Transform_), BaseType(BaseType_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Transform, BaseType); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Transform;
+    OB += '(';
+    BaseType->print(OB);
+    OB += ')';
+  }
+};
+
 struct AbiTagAttr : Node {
   Node *Base;
   std::string_view Tag;
@@ -4124,7 +4141,15 @@ Node *AbstractManglingParser<Derived, Alloc>::parseType() {
     // 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);
+    if (consumeIf('I')) {
+      Node *BaseType = parseType();
+      if (BaseType == nullptr)
+        return nullptr;
+      if (!consumeIf('E'))
+        return nullptr;
+      Result = make<TransformedType>(Res, BaseType);
+    } else
+      Result = make<NameType>(Res);
     break;
   }
   case 'D':
diff --git a/llvm/include/llvm/Demangle/ItaniumNodes.def b/llvm/include/llvm/Demangle/ItaniumNodes.def
index 12cfa70f93e63..30a93eccaee37 100644
--- a/llvm/include/llvm/Demangle/ItaniumNodes.def
+++ b/llvm/include/llvm/Demangle/ItaniumNodes.def
@@ -19,6 +19,7 @@ NODE(QualType)
 NODE(ConversionOperatorType)
 NODE(PostfixQualifiedType)
 NODE(ElaboratedTypeSpefType)
+NODE(TransformedType)
 NODE(NameType)
 NODE(AbiTagAttr)
 NODE(EnableIfAttr)