diff --git a/libcxx/utils/libcxx/test/config.py b/libcxx/utils/libcxx/test/config.py
--- a/libcxx/utils/libcxx/test/config.py
+++ b/libcxx/utils/libcxx/test/config.py
@@ -245,7 +245,7 @@
         # XFAIL markers for tests that are known to fail with versions of
         # libc++ as were shipped with a particular triple.
         if self.use_system_cxx_lib:
-            (arch, vendor, platform) = self.config.target_triple.split('-')
+            (arch, vendor, platform) = self.config.target_triple.split('-', 2)
             (sysname, version) = re.match(r'([^0-9]+)([0-9\.]*)', platform).groups()
 
             self.config.available_features.add('with_system_cxx_lib={}-{}-{}{}'.format(arch, vendor, sysname, version))