Index: utils/libcxx/test/config.py
===================================================================
--- utils/libcxx/test/config.py
+++ utils/libcxx/test/config.py
@@ -524,6 +524,7 @@
                 maj_v = int(maj_v)
                 if maj_v < 7:
                     possible_stds.remove('c++1z')
+                    possible_stds.remove('c++17')
                 # FIXME: How many C++14 tests actually fail under GCC 5 and 6?
                 # Should we XFAIL them individually instead?
                 if maj_v <= 6: