Index: libcxxabi/src/demangle/ItaniumDemangle.h
===================================================================
--- libcxxabi/src/demangle/ItaniumDemangle.h
+++ libcxxabi/src/demangle/ItaniumDemangle.h
@@ -1785,7 +1785,8 @@
   template<typename Fn> void match(Fn F) const { F(LHS, InfixOperator, RHS); }
 
   void printLeft(OutputBuffer &OB) const override {
-    bool ParenAll = OB.isGtInsideTemplateArgs() && InfixOperator == ">";
+    bool ParenAll = OB.isGtInsideTemplateArgs() &&
+                    (InfixOperator == ">" || InfixOperator == ">>");
     if (ParenAll)
       OB.printOpen();
     // Assignment is right associative, with special LHS precedence.
Index: libcxxabi/test/test_demangle.pass.cpp
===================================================================
--- libcxxabi/test/test_demangle.pass.cpp
+++ libcxxabi/test/test_demangle.pass.cpp
@@ -29629,7 +29629,7 @@
     {"_ZN5Casts8implicitILj4EEEvPN9enable_ifIXrMT_Li4EEvE4typeE",
      "void Casts::implicit<4u>(enable_if<4u %= 4, void>::type*)"},
     {"_ZN5Casts8implicitILj4EEEvPN9enable_ifIXrsT_Li4EEvE4typeE",
-     "void Casts::implicit<4u>(enable_if<4u >> 4, void>::type*)"},
+     "void Casts::implicit<4u>(enable_if<(4u >> 4), void>::type*)"},
     {"_ZN5Casts8implicitILj4EEEvPN9enable_ifIXrST_Li4EEvE4typeE",
      "void Casts::implicit<4u>(enable_if<4u >>= 4, void>::type*)"},
     {"_Z1fPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP1XS13_S12_S11_S10_SZ_SY_SX_SW_SV_SU_ST_SS_SR_SQ_SP_SO_SN_SM_SL_SK_SJ_"
Index: llvm/include/llvm/Demangle/ItaniumDemangle.h
===================================================================
--- llvm/include/llvm/Demangle/ItaniumDemangle.h
+++ llvm/include/llvm/Demangle/ItaniumDemangle.h
@@ -1785,7 +1785,8 @@
   template<typename Fn> void match(Fn F) const { F(LHS, InfixOperator, RHS); }
 
   void printLeft(OutputBuffer &OB) const override {
-    bool ParenAll = OB.isGtInsideTemplateArgs() && InfixOperator == ">";
+    bool ParenAll = OB.isGtInsideTemplateArgs() &&
+                    (InfixOperator == ">" || InfixOperator == ">>");
     if (ParenAll)
       OB.printOpen();
     // Assignment is right associative, with special LHS precedence.