diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.assign/unique_ptr_Y.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.assign/unique_ptr_Y.pass.cpp
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.assign/unique_ptr_Y.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.assign/unique_ptr_Y.pass.cpp
@@ -125,6 +125,8 @@
     assert(B::count == 0);
     assert(A::count == 0);
 
+#ifdef _LIBCPP_VERSION // Bogus test cases assign unique_ptr<Y> to shared_ptr<T> despite that
+                       // Y* and T* are not compatible per [util.smartptr.shared.general]/6.
     {
       std::unique_ptr<A[]> ptr(new A[8]);
       A* raw_ptr = ptr.get();
@@ -156,6 +158,7 @@
       std::shared_ptr<int> p;
       p = std::move(ptr);
     }
+#endif // _LIBCPP_VERSION
 
 #if TEST_STD_VER > 14
     {
@@ -169,6 +172,8 @@
     assert(A::count == 0);
     assert(B::count == 0);
 
+#ifdef _LIBCPP_VERSION // Bogus test case assigns unique_ptr<Y> to shared_ptr<T> despite that
+                       // Y* and T* are not compatible per [util.smartptr.shared.general]/6.
     {
       std::unique_ptr<A[]> ptr(new A[8]);
       A* raw_ptr = ptr.get();
@@ -182,6 +187,7 @@
     }
     assert(A::count == 0);
     assert(B::count == 0);
+#endif // _LIBCPP_VERSION
 
     {
       std::unique_ptr<A[]> ptr(new A[8]);
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/unique_ptr.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/unique_ptr.pass.cpp
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/unique_ptr.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/unique_ptr.pass.cpp
@@ -149,6 +149,8 @@
     }
 
     assert(A::count == 0);
+#ifdef _LIBCPP_VERSION // Bogus test cases initialize shared_ptr<T> with unique_ptr<Y> despite that
+                       // Y* and T* are not compatible per [util.smartptr.shared.general]/6.
     {
       std::unique_ptr<A[]> ptr(new A[8]);
       A* raw_ptr = ptr.get();
@@ -177,6 +179,7 @@
       std::unique_ptr<int[]> ptr(new int[8]);
       std::shared_ptr<int> p(std::move(ptr));
     }
+#endif // _LIBCPP_VERSION
 
 #if TEST_STD_VER > 14
     {
@@ -189,6 +192,8 @@
     assert(A::count == 0);
     assert(B::count == 0);
 
+#ifdef _LIBCPP_VERSION // Bogus test case initializes shared_ptr<T> with unique_ptr<Y> despite that
+                       // Y* and T* are not compatible per [util.smartptr.shared.general]/6.
     {
       std::unique_ptr<A[]> ptr(new A[8]);
       A* raw_ptr = ptr.get();
@@ -201,6 +206,7 @@
     }
     assert(A::count == 0);
     assert(B::count == 0);
+#endif // _LIBCPP_VERSION
 
     {
       std::unique_ptr<A[]> ptr(new A[8]);