diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index c02fb52..359dc96 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1125,7 +1125,7 @@
                            restore_signals, start_new_session):
             """Execute program (POSIX version)"""
 
-            if isinstance(args, str):
+            if isinstance(args, (str, bytes)):
                 args = [args]
             else:
                 args = list(args)
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 9e267eb..d91a4a6 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -1059,6 +1059,11 @@
         exitcode = subprocess.call([abs_program, "-c", "pass"])
         self.assertEqual(exitcode, 0)
 
+        # absolute bytes path as a string
+        cmd = b"'" + abs_program + b"' -c pass"
+        exitcode = subprocess.call(cmd, shell=True)
+        self.assertEqual(exitcode, 0)
+
         # bytes program, unicode PATH
         env = os.environ.copy()
         env["PATH"] = path
diff --git a/Misc/NEWS b/Misc/NEWS
index da1b75d..128efa2 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -52,6 +52,8 @@
 Library
 -------
 
+- Issue #8513: On UNIX, subprocess supports bytes command string.
+
 - Issue #10866: Add socket.sethostname().  Initial patch by Ross Lagerwall.
 
 - Issue #11140: Lock.release() now raises a RuntimeError when attempting