--- a/Makefile.in
+++ b/Makefile.in
@@ -25,8 +25,9 @@ CC = @CC@
 INSTALL = @INSTALL@
 DEFS = @DEFS@
 LIBS = @LIBS@
-CFLAGS = -O
-LDFLAGS = -s
+CFLAGS = @CFLAGS@
+CPPFLAGS = @CPPFLAGS@
+LDFLAGS = @LDFLAGS@
 prefix = @prefix@
 
 SHELL = /bin/sh
