Index: libcxxabi/src/demangle/ItaniumDemangle.h
===================================================================
--- libcxxabi/src/demangle/ItaniumDemangle.h
+++ libcxxabi/src/demangle/ItaniumDemangle.h
@@ -3926,7 +3926,8 @@
         return nullptr;
       if (!consumeIf('_'))
         return nullptr;
-      return make<BitIntType>(Size, Signed);
+      Result = make<BitIntType>(Size, Signed);
+      break;
     }
     //                ::= Di   # char32_t
     case 'i':
Index: libcxxabi/test/test_demangle.pass.cpp
===================================================================
--- libcxxabi/test/test_demangle.pass.cpp
+++ libcxxabi/test/test_demangle.pass.cpp
@@ -33,6 +33,7 @@
     {"_Z1Av", "A()"},
     {"_Z1A1B1C", "A(B, C)"},
     {"_Z1fDB3_", "f(_BitInt(3))"},
+    {"_Z1fDB3_S_", "f(_BitInt(3), _BitInt(3))"},
     {"_Z1fDU10_", "f(unsigned _BitInt(10))"},
     {"_Z1fIfEvDUstPT__", "void f<float>(unsigned _BitInt(sizeof (float*)))"},
     {"_Z1fIiEvDBstPT__", "void f<int>(_BitInt(sizeof (int*)))"},
Index: llvm/include/llvm/Demangle/ItaniumDemangle.h
===================================================================
--- llvm/include/llvm/Demangle/ItaniumDemangle.h
+++ llvm/include/llvm/Demangle/ItaniumDemangle.h
@@ -3926,7 +3926,8 @@
         return nullptr;
       if (!consumeIf('_'))
         return nullptr;
-      return make<BitIntType>(Size, Signed);
+      Result = make<BitIntType>(Size, Signed);
+      break;
     }
     //                ::= Di   # char32_t
     case 'i':