Index: libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_nothrow_replace.pass.cpp
===================================================================
--- libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_nothrow_replace.pass.cpp
+++ libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_nothrow_replace.pass.cpp
@@ -11,6 +11,11 @@
 // UNSUPPORTED: sanitizer-new-delete
 // XFAIL: libcpp-no-vcruntime
 
+// z/OS has different runtime linking model, references are determined at 
+// link step, C++RT new or new[] operator will call the new operator it knows
+// about in shared library not the one user defined.
+// UNSUPPORTED: target={{.+}}-zos{{.*}}
+
 #include <new>
 #include <cstddef>
 #include <cstdlib>
Index: libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_replace.pass.cpp
===================================================================
--- libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_replace.pass.cpp
+++ libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_replace.pass.cpp
@@ -11,6 +11,10 @@
 // UNSUPPORTED: sanitizer-new-delete
 // XFAIL: libcpp-no-vcruntime
 
+// z/OS has different runtime linking model, references are determined at 
+// link step, C++RT new or new[] operator will call the new operator it knows
+// about in shared library not the one user defined.
+// UNSUPPORTED: target={{.+}}-zos{{.*}}
 
 #include <new>
 #include <cstddef>
Index: libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_nothrow_replace.pass.cpp
===================================================================
--- libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_nothrow_replace.pass.cpp
+++ libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_nothrow_replace.pass.cpp
@@ -11,6 +11,11 @@
 // UNSUPPORTED: sanitizer-new-delete
 // XFAIL: libcpp-no-vcruntime
 
+// z/OS has different runtime linking model, references are determined at
+// link step, C++RT new or new[] operator will call the new operator it knows
+// about in shared library not the one user defined.
+// UNSUPPORTED: target={{.+}}-zos{{.*}}
+
 #include <new>
 #include <cstddef>
 #include <cstdlib>