diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -2832,7 +2832,7 @@
   // All integrals and enums are unique.
   if (Ty->isIntegralOrEnumerationType()) {
     // Except _BitInt types that have padding bits.
-    if (const auto *BIT = dyn_cast<BitIntType>(Ty))
+    if (const auto *BIT = Ty->getAs<BitIntType>())
       return getTypeSize(BIT) == BIT->getNumBits();
 
     return true;
diff --git a/clang/test/SemaCXX/type-traits.cpp b/clang/test/SemaCXX/type-traits.cpp
--- a/clang/test/SemaCXX/type-traits.cpp
+++ b/clang/test/SemaCXX/type-traits.cpp
@@ -2970,6 +2970,12 @@
   bool b = __has_unique_object_representations(T);
 };
 
+static_assert(!has_unique_object_representations<_BitInt(7)>::value, "BitInt:");
+static_assert(has_unique_object_representations<_BitInt(8)>::value, "BitInt:");
+static_assert(!has_unique_object_representations<_BitInt(127)>::value, "BitInt:");
+static_assert(has_unique_object_representations<_BitInt(128)>::value, "BitInt:");
+
+
 namespace PR46209 {
   // Foo has both a trivial assignment operator and a non-trivial one.
   struct Foo {