diff --git a/Lib/test/output/test_bufio b/Lib/test/output/test_bufio
new file mode 100644
index 0000000..c153797
--- /dev/null
+++ b/Lib/test/output/test_bufio
@@ -0,0 +1 @@
+test_bufio
diff --git a/Lib/test/test_bufio.py b/Lib/test/test_bufio.py
new file mode 100644
index 0000000..1a820d4
--- /dev/null
+++ b/Lib/test/test_bufio.py
@@ -0,0 +1,60 @@
+from test_support import TestFailed, TESTFN
+
+# Simple test to ensure that optimizations in fileobject.c deliver
+# the expected results.  For best testing, run this under a debug-build
+# Python too (to exercise asserts in the C code).
+
+# Repeat string 'pattern' as often as needed to reach total length
+# 'length'.  Then call try_one with that string, a string one larger
+# than that, and a string one smaller than that.  The main driver
+# feeds this all small sizes and various powers of 2, so we exercise
+# all likely stdio buffer sizes, and "off by one" errors on both
+# sides.
+def drive_one(pattern, length):
+    q, r = divmod(length, len(pattern))
+    teststring = pattern * q + pattern[:r]
+    assert len(teststring) == length
+    try_one(teststring)
+    try_one(teststring + "x")
+    try_one(teststring[:-1])
+
+# Write s + "\n" + s to file, then open it and ensure that successive
+# .readline()s deliver what we wrote.
+def try_one(s):
+    # Since C doesn't guarantee we can write/read arbitrary bytes in text
+    # files, use binary mode.
+    f = open(TESTFN, "wb")
+    # write once with \n and once without
+    f.write(s)
+    f.write("\n")
+    f.write(s)
+    f.close()
+    f = open(TESTFN, "rb")
+    line = f.readline()
+    if line != s + "\n":
+        raise TestFailed("Expected %r got %r" % (s + "\n", line))
+    line = f.readline()
+    if line != s:
+        raise TestFailed("Expected %r got %r" % (s, line))
+    line = f.readline()
+    if line:
+        raise TestFailed("Expected EOF but got %r" % line)
+    f.close()
+
+# A pattern with prime length, to avoid simple relationships with
+# stdio buffer sizes.
+primepat = "1234567890\00\01\02\03\04\05\06\07"
+
+nullpat = "\0" * 1000
+
+try:
+    for size in range(1, 257) + [512, 1000, 1024, 2048, 4096, 8192, 10000,
+                      16384, 32768, 65536, 1000000]:
+        drive_one(primepat, size)
+        drive_one(nullpat, size)
+finally:
+    try:
+        import os
+        os.unlink(TESTFN)
+    except:
+        pass