Index: utils/lit/lit/TestRunner.py
===================================================================
--- utils/lit/lit/TestRunner.py
+++ utils/lit/lit/TestRunner.py
@@ -245,6 +245,10 @@
                 if r[2] is None:
                     if kAvoidDevNull and r[0] == '/dev/null':
                         r[2] = tempfile.TemporaryFile(mode=r[1])
+                    elif kIsWindows and r[0] == '/dev/tty':
+                        # Simulate /dev/tty on Windows.
+                        # "CON:" is a special filename for the console.
+                        r[2] = open("CON:", r[1])
                     else:
                         # Make sure relative paths are relative to the cwd.
                         redir_filename = os.path.join(cmd_shenv.cwd, r[0])