--- Makefile.in
+++ Makefile.in
@@ -153,7 +153,7 @@
 AWK = @AWK@
 CC = @CC@
 CCDEPMODE = @CCDEPMODE@
-CFLAGS = -O2 -fno-builtin -Wall -DSBINDIR='"$(sbindir)"'
+CFLAGS = @CFLAGS@ -fno-builtin -Wall -DSBINDIR='"$(sbindir)"'
 CPP = @CPP@
 CPPFLAGS = @CPPFLAGS@
 CYGPATH_W = @CYGPATH_W@