Index: Lib/test/regrtest.py
===================================================================
--- Lib/test/regrtest.py	(revision 84663)
+++ Lib/test/regrtest.py	(working copy)
@@ -736,13 +736,12 @@
 def replace_stdout():
     """Set stdout encoder error handler to backslashreplace (as stderr error
     handler) to avoid UnicodeEncodeError when printing a traceback"""
-    if os.name == "nt":
-        # Replace sys.stdout breaks the stdout newlines on Windows: issue #8533
-        return
     stdout = sys.stdout
-    sys.stdout = open(stdout.fileno(), 'w',
-        encoding=stdout.encoding,
-        errors="backslashreplace")
+    buf = io.open(stdout.fileno(), "wb")
+    buf.raw.name = "<stdout>"
+    line_buffering = buf.raw.isatty()
+    sys.stdout = io.TextIOWrapper(buf,
+        stdout.encoding, "backslashreplace", "\n", line_buffering)
 
 def runtest(test, verbose, quiet,
             testdir=None, huntrleaks=False, debug=False, use_resources=None):