Index: setup.py
--- setup.py.orig
+++ setup.py
@@ -33,8 +33,6 @@ def _libuv_build_env():
     env = os.environ.copy()
 
     cur_cflags = env.get('CFLAGS', '')
-    if not re.search(r'-O\d', cur_cflags):
-        cur_cflags += ' -O2'
 
     env['CFLAGS'] = (cur_cflags + ' -fPIC ' + env.get('ARCHFLAGS', ''))
 
@@ -83,8 +81,8 @@ class uvloop_build_ext(build_ext):
 
     def initialize_options(self):
         super().initialize_options()
-        self.use_system_libuv = False
-        self.cython_always = False
+        self.use_system_libuv = True
+        self.cython_always = True
         self.cython_annotate = None
         self.cython_directives = None
 
