diff --git a/llvm/test/Unit/lit.cfg b/llvm/test/Unit/lit.cfg
index 30a5d3fab826..dac0bf829ba6 100644
--- a/llvm/test/Unit/lit.cfg
+++ b/llvm/test/Unit/lit.cfg
@@ -43,6 +43,10 @@ if sys.platform in ['win32', 'cygwin'] and os.path.isdir(config.shlibdir):
     config.environment['PATH'] = os.path.pathsep.join((
             config.shlibdir, config.environment['PATH']))
 
+# Win32 may use %SYSTEMDRIVE% during file system shell operations, so propogate.
+if sys.platform == 'win32' and 'SYSTEMDRIVE' in os.environ:
+    config.environment['SYSTEMDRIVE'] = os.environ['SYSTEMDRIVE']
+
 ###
 
 # Check that the object root is known.