diff --git a/Lib/codecs.py b/Lib/codecs.py
index a70ed20f2b..9fa4dd7926 100644
--- a/Lib/codecs.py
+++ b/Lib/codecs.py
@@ -9,6 +9,7 @@ Written by Marc-Andre Lemburg (mal@lemburg.com).
 
 import builtins
 import sys
+import re
 
 ### Registry and builtin stateless codec functions
 
@@ -416,6 +417,46 @@ class StreamWriter(Codec):
 
 ###
 
+
+def _str_splitlines(s, keepends=False,
+                    pat=re.compile(r'(\r\n|\r|\n)'),
+                    ends_pat=re.compile(r'.*?(\r\n|\r|\n)'),
+                   ):
+    if keepends:
+        lines = []
+        matches = list(ends_pat.finditer(s))
+        if matches:
+            lines.extend(m.group() for m in matches)
+            last = matches[-1]
+            if last.end() != len(s):
+                lines.append(s[last.end():])
+    else:
+        lines = pat.split(s)
+        if lines:
+            lines[-1] = lines[-1].rstrip('\r\n')
+    return lines
+
+
+def _bytes_splitlines(s, keepends=False,
+                      pat=re.compile(rb'\r?\n'),
+                      ends_pat=re.compile(rb'.*?\r?\n'),
+                     ):
+    if keepends:
+        lines = []
+        matches = list(ends_pat.finditer(s))
+        if matches:
+            lines.extend(m.group() for m in matches)
+            last = matches[-1]
+            if last.end() != len(s):
+                lines.append(s[last.end():])
+    else:
+        lines = pat.split(s)
+        if lines:
+            lines[-1] = lines[-1].rstrip(b'\r')
+    return lines
+
+
+
 class StreamReader(Codec):
 
     charbuffertype = str
@@ -442,6 +483,10 @@ class StreamReader(Codec):
         self.errors = errors
         self.bytebuffer = b""
         self._empty_charbuffer = self.charbuffertype()
+        if isinstance(self._empty_charbuffer, str):
+            self._splitlines = _str_splitlines
+        else:
+            self._splitlines = _bytes_splitlines
         self.charbuffer = self._empty_charbuffer
         self.linebuffer = None
 
@@ -506,7 +551,7 @@ class StreamReader(Codec):
                 if firstline:
                     newchars, decodedbytes = \
                         self.decode(data[:exc.start], self.errors)
-                    lines = newchars.splitlines(keepends=True)
+                    lines = self._splitlines(newchars, keepends=True)
                     if len(lines)<=1:
                         raise
                 else:
@@ -548,7 +593,7 @@ class StreamReader(Codec):
                 self.charbuffer = self.linebuffer[0]
                 self.linebuffer = None
             if not keepends:
-                line = line.splitlines(keepends=False)[0]
+                line = self._splitlines(line, keepends=False)[0]
             return line
 
         readsize = size or 72
@@ -565,7 +610,7 @@ class StreamReader(Codec):
                     data += self.read(size=1, chars=1)
 
             line += data
-            lines = line.splitlines(keepends=True)
+            lines = self._splitlines(line, keepends=True)
             if lines:
                 if len(lines) > 1:
                     # More than one line result; the first line is a full line
@@ -581,10 +626,10 @@ class StreamReader(Codec):
                         # only one remaining line, put it back into charbuffer
                         self.charbuffer = lines[0] + self.charbuffer
                     if not keepends:
-                        line = line.splitlines(keepends=False)[0]
+                        line = self._splitlines(line, keepends=False)[0]
                     break
                 line0withend = lines[0]
-                line0withoutend = lines[0].splitlines(keepends=False)[0]
+                line0withoutend = self._splitlines(lines[0], keepends=False)[0]
                 if line0withend != line0withoutend: # We really have a line end
                     # Put the rest back together and keep it until the next call
                     self.charbuffer = self._empty_charbuffer.join(lines[1:]) + \
@@ -597,7 +642,7 @@ class StreamReader(Codec):
             # we didn't get anything or this was our only try
             if not data or size is not None:
                 if line and not keepends:
-                    line = line.splitlines(keepends=False)[0]
+                    line = self._splitlines(line, keepends=False)[0]
                 break
             if readsize < 8000:
                 readsize *= 2
@@ -616,7 +661,7 @@ class StreamReader(Codec):
 
         """
         data = self.read()
-        return data.splitlines(keepends)
+        return self._splitlines(data, keepends)
 
     def reset(self):
 
@@ -819,7 +864,7 @@ class StreamRecoder:
 
         data = self.reader.read()
         data, bytesencoded = self.encode(data, self.errors)
-        return data.splitlines(keepends=True)
+        return self._splitlines(data, keepends=True)
 
     def __next__(self):
 
diff --git a/Lib/test/test_codecs.py b/Lib/test/test_codecs.py
index 00b5d317c4..b5f43fe173 100644
--- a/Lib/test/test_codecs.py
+++ b/Lib/test/test_codecs.py
@@ -143,14 +143,14 @@ class ReadTest(MixInCheckStateHandling):
             return "|".join(lines)
 
         s = "foo\nbar\r\nbaz\rspam\u2028eggs"
-        sexpected = "foo\n|bar\r\n|baz\r|spam\u2028|eggs"
-        sexpectednoends = "foo|bar|baz|spam|eggs"
+        sexpected = "foo\n|bar\r\n|baz\r|spam\u2028eggs"
+        sexpectednoends = "foo|bar|baz|spam\u2028eggs"
         self.assertEqual(readalllines(s, True), sexpected)
         self.assertEqual(readalllines(s, False), sexpectednoends)
         self.assertEqual(readalllines(s, True, 10), sexpected)
         self.assertEqual(readalllines(s, False, 10), sexpectednoends)
 
-        lineends = ("\n", "\r\n", "\r", "\u2028")
+        lineends = ("\n", "\r\n", "\r")
         # Test long lines (multiple calls to read() in readline())
         vw = []
         vwo = []