diff --git a/git/cmd.py b/git/cmd.py
index c99c04e2c..2f900ae20 100644
--- a/git/cmd.py
+++ b/git/cmd.py
@@ -605,6 +605,7 @@ def execute(self, command,
             proc = Popen(command,
                          env=env,
                          cwd=cwd,
+                         bufsize=-1,
                          stdin=istream,
                          stderr=PIPE,
                          stdout=with_stdout and PIPE or None,