diff --git a/Lib/http/server.py b/Lib/http/server.py
--- a/Lib/http/server.py
+++ b/Lib/http/server.py
@@ -12,9 +12,6 @@
 
 This class implements GET and POST requests to cgi-bin scripts.
 
-If the os.fork() function is not present (e.g. on Windows),
-subprocess.Popen() is used as a fallback, with slightly altered semantics.
-
 In all cases, the implementation is intentionally naive -- all
 requests are executed synchronously.
 
@@ -96,6 +93,7 @@
 import shutil
 import socket # For gethostbyaddr()
 import socketserver
+import subprocess
 import sys
 import time
 import urllib.parse
@@ -922,9 +920,6 @@
 
     """
 
-    # Determine platform specifics
-    have_fork = hasattr(os, 'fork')
-
     # Make rfile unbuffered -- we need to read one line and then pass
     # the rest to a subprocess, so we can't use buffered input.
     rbufsize = 0
@@ -1024,8 +1019,7 @@
             self.send_error(403, "CGI script is not a plain file (%r)" %
                             scriptname)
             return
-        ispy = self.is_python(scriptname)
-        if self.have_fork or not ispy:
+        if os.name == 'posix' or not self.is_python(scriptfile):
             if not self.is_executable(scriptfile):
                 self.send_error(403, "CGI script is not executable (%r)" %
                                 scriptname)
@@ -1098,53 +1092,37 @@
 
         self.send_response(200, "Script output follows")
         self.flush_headers()
+        self.wfile.flush()
 
         decoded_query = query.replace('+', ' ')
 
-        if self.have_fork:
-            # Unix -- fork as we should
-            args = [script]
-            if '=' not in decoded_query:
-                args.append(decoded_query)
-            nobody = nobody_uid()
-            self.wfile.flush() # Always flush before forking
-            pid = os.fork()
-            if pid != 0:
-                # Parent
-                pid, sts = os.waitpid(pid, 0)
-                # throw away additional data [see bug #427345]
-                while select.select([self.rfile], [], [], 0)[0]:
-                    if not self.rfile.read(1):
-                        break
-                if sts:
-                    self.log_error("CGI script exit status %#x", sts)
-                return
-            # Child
-            try:
+        cmdline = [scriptfile]
+        if self.is_python(scriptfile):
+            interp = sys.executable
+            if os.name == 'nt' and interp.lower().endswith("w.exe"):
+                # On Windows, use python.exe, not pythonw.exe
+                interp = interp[:-5] + interp[-4:]
+            cmdline = [interp, '-u'] + cmdline
+
+        if '=' not in decoded_query:
+            cmdline.append(decoded_query)
+
+        self.log_message("command: %s", subprocess.list2cmdline(cmdline))
+
+        if os.name == 'posix':
+            def reduce_privilege():
+                nobody = nobody_uid()
                 try:
                     os.setuid(nobody)
                 except OSError:
                     pass
-                os.dup2(self.rfile.fileno(), 0)
-                os.dup2(self.wfile.fileno(), 1)
-                os.execve(scriptfile, args, env)
-            except:
-                self.server.handle_error(self.request, self.client_address)
-                os._exit(127)
 
+            p = subprocess.Popen(cmdline, stdin=self.rfile,
+                                          stdout=self.wfile,
+                                          env=env,
+                                          preexec_fn=reduce_privilege)
+            status = p.wait()
         else:
-            # Non-Unix -- use subprocess
-            import subprocess
-            cmdline = [scriptfile]
-            if self.is_python(scriptfile):
-                interp = sys.executable
-                if interp.lower().endswith("w.exe"):
-                    # On Windows, use python.exe, not pythonw.exe
-                    interp = interp[:-5] + interp[-4:]
-                cmdline = [interp, '-u'] + cmdline
-            if '=' not in query:
-                cmdline.append(query)
-            self.log_message("command: %s", subprocess.list2cmdline(cmdline))
             try:
                 nbytes = int(length)
             except (TypeError, ValueError):
@@ -1153,27 +1131,28 @@
                                  stdin=subprocess.PIPE,
                                  stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE,
-                                 env = env
-                                 )
+                                 env = env)
             if self.command.lower() == "post" and nbytes > 0:
                 data = self.rfile.read(nbytes)
             else:
                 data = None
-            # throw away additional data [see bug #427345]
-            while select.select([self.rfile._sock], [], [], 0)[0]:
-                if not self.rfile._sock.recv(1):
-                    break
             stdout, stderr = p.communicate(data)
             self.wfile.write(stdout)
             if stderr:
                 self.log_error('%s', stderr)
             p.stderr.close()
             p.stdout.close()
-            status = p.returncode
-            if status:
-                self.log_error("CGI script exit status %#x", status)
-            else:
-                self.log_message("CGI script exited OK")
+        status = p.wait()
+
+        # throw away additional data [see bug #427345]
+        while select.select([self.rfile._sock], [], [], 0)[0]:
+            if not self.rfile._sock.recv(1):
+                break
+
+        if status:
+            self.log_error("CGI script exit status %#x", status)
+        else:
+            self.log_message("CGI script exited OK")
 
 
 def test(HandlerClass = BaseHTTPRequestHandler,