diff -Naur dev86-0.16.17.old/Makefile dev86-0.16.17/Makefile
--- dev86-0.16.17.old/Makefile	2004-06-20 17:57:52.000000000 +0000
+++ dev86-0.16.17/Makefile	2007-11-01 22:37:39.000000000 +0000
@@ -18,7 +18,7 @@
 INCLDIR= $(PREFIX)/lib/bcc
 ASLDDIR= $(BINDIR)
 MANDIR=	 $(PREFIX)/man
-CFLAGS=  -O
+CFLAGS=  -O2 -march=i486 -mtune=i686
 
 # Some makes take the last of a list as the default ...
 all: make.fil
diff -Naur dev86-0.16.17.old/ar/Makefile dev86-0.16.17/ar/Makefile
--- dev86-0.16.17.old/ar/Makefile	2003-08-31 12:54:08.000000000 +0000
+++ dev86-0.16.17/ar/Makefile	2007-11-01 22:38:11.000000000 +0000
@@ -3,7 +3,7 @@
 # distributed under the GNU General Public License.
 
 LIBDIR	=/usr/bin
-CFLAGS	=-O
+CFLAGS	=-O2 -march -mtune=i686
 LDFLAGS	=
 DEFS	=
 OBJS= ar.o alloca.o
diff -Naur dev86-0.16.17.old/as/Makefile dev86-0.16.17/as/Makefile
--- dev86-0.16.17.old/as/Makefile	2003-12-31 11:36:39.000000000 +0000
+++ dev86-0.16.17/as/Makefile	2007-11-01 22:38:36.000000000 +0000
@@ -1,5 +1,5 @@
 
-CFLAGS=-O
+CFLAGS=-O2 -march=i486 -mtune=i686
 LDFLAGS=-s
 LIBDIR=/usr/bin
 BINDIR=/usr/bin
diff -Naur dev86-0.16.17.old/bcc/Makefile dev86-0.16.17/bcc/Makefile
--- dev86-0.16.17.old/bcc/Makefile	2004-06-20 17:15:21.000000000 +0000
+++ dev86-0.16.17/bcc/Makefile	2007-11-01 22:38:54.000000000 +0000
@@ -5,7 +5,7 @@
 
 PREFIX=/usr
 
-CFLAGS	=-O
+CFLAGS	=-O2 -march=i486 -mtune=i686
 LDFLAGS	=-s
 BINDIR	=$(PREFIX)/bin
 LIBDIR	=$(PREFIX)/lib/bcc
diff -Naur dev86-0.16.17.old/bin86/Makefile dev86-0.16.17/bin86/Makefile
--- dev86-0.16.17.old/bin86/Makefile	2003-12-31 11:36:40.000000000 +0000
+++ dev86-0.16.17/bin86/Makefile	2007-11-01 22:39:23.000000000 +0000
@@ -1,5 +1,5 @@
 
-CFLAGS=-O2 -D_POSIX_SOURCE
+CFLAGS=-O2 -march=i486 -mtune=i686 -D_POSIX_SOURCE
 LDFLAGS=
 DIRS=ld as
 
diff -Naur dev86-0.16.17.old/bootblocks/Makefile dev86-0.16.17/bootblocks/Makefile
--- dev86-0.16.17.old/bootblocks/Makefile	2004-01-24 10:55:38.000000000 +0000
+++ dev86-0.16.17/bootblocks/Makefile	2007-11-01 22:41:19.000000000 +0000
@@ -1,12 +1,12 @@
 
 HOSTCC=cc
-HOSTCCFLAGS=-O
+HOSTCCFLAGS=-O2 -march=i486 -mtune=i686
 BCC=bcc
 AS86=as86
 
 DEFS=
 CC=$(BCC)
-CFLAGS=-ansi -Ms -Oi -O $(DEFS)
+CFLAGS=-ansi -Ms -O2 -march=i486 -mtune=i686 $(DEFS)
 LDFLAGS=-s -i -H0x10000 
 ASFLAGS=-0 -w
 MINIXDEFS=-DDOTS
@@ -82,13 +82,13 @@
 bzimage.o: bzimage.c zimage.v
 
 minix.s: minix.c Makefile
-	$(CC) -Mf -O -DTRY_FLOPPY $(MINIXDEFS) -S minix.c
+	$(CC) -Mf -O2 -march=i486 -mtune=i686 -DTRY_FLOPPY $(MINIXDEFS) -S minix.c
 
 minix_elks.s: minix_elks.c Makefile minix.v
-	$(CC) -Mf -O $(MINIXDEFS) -S minix_elks.c
+	$(CC) -Mf -O2 -march=i486 -mtune=i686 $(MINIXDEFS) -S minix_elks.c
 
 minixhd.s: minix.c Makefile
-	$(CC) -Mf -O -DHARDDISK $(MINIXDEFS) -S minix.c -o minixhd.s
+	$(CC) -Mf -O2 -march=i486 -mtune=i686 -DHARDDISK $(MINIXDEFS) -S minix.c -o minixhd.s
 
 msdos16.s: msdos.s
 	sed 's/^fatbits=12/fatbits=16/' < msdos.s > msdos16.s
@@ -107,10 +107,10 @@
 	$(HOSTCC) $(HOSTCCFLAGS) -o makeboot makeboot.c
 
 makeboot.com:	makeboot.c $(BOOTBLOCKS)
-	$(CC) -Md -O -o makeboot.com makeboot.c
+	$(CC) -Md -O2 -march=i486 -mtune=i686 -o makeboot.com makeboot.c
 
 lsys.com:	lsys.c msdos.v msdos16.v
-	$(CC) -Md -O -o lsys.com lsys.c
+	$(CC) -Md -O2 -march=i486 -mtune=i686 -o lsys.com lsys.c
 
 clean realclean:
 	rm -f bootfile.sys boottar.sys bootminix.sys monitor.sys boot_win.sys
diff -Naur dev86-0.16.17.old/dis88/Makefile dev86-0.16.17/dis88/Makefile
--- dev86-0.16.17.old/dis88/Makefile	1998-07-31 13:01:40.000000000 +0000
+++ dev86-0.16.17/dis88/Makefile	2007-11-01 22:41:42.000000000 +0000
@@ -25,7 +25,7 @@
 # be necessary to alter the formats of the tables.
 
 #CC=bcc
-CFLAGS=-O
+CFLAGS=-O2 -march=i486 -mtune=i686
 LDFLAGS=
 PREFIX=/usr
 
diff -Naur dev86-0.16.17.old/elksemu/Makefile dev86-0.16.17/elksemu/Makefile
--- dev86-0.16.17.old/elksemu/Makefile	2004-10-02 13:58:49.000000000 +0000
+++ dev86-0.16.17/elksemu/Makefile	2007-11-01 22:42:27.000000000 +0000
@@ -12,7 +12,7 @@
 
 # Default
 ifeq ($(CFLAGS),)
-CFLAGS=-O
+CFLAGS=-O2 -march=i486 -mtune=i686
 endif
 
 # Turn on elkemu's strace like facility.
@@ -53,7 +53,7 @@
 # BUT remember you don't need it for a recent 2.1.X; use binfmt_misc.
 
 # This matches my compile (2.0.x); yours may be different.
-MODCFLAGS=-D__KERNEL__ -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer \
+MODCFLAGS=-D__KERNEL__ -Wall -Wstrict-prototypes -O2 -march=i486 -mtune=i686 -fomit-frame-pointer \
           -fno-strength-reduce -pipe -m486 -DCPU=486 -DMODULE -DMODVERSIONS \
 	  -include /usr/include/linux/modversions.h
 
@@ -61,7 +61,7 @@
 	gcc -c $(MODCFLAGS) binfmt_elks.c
 
 # This is another option
-#MODCFLAGS=-O -fomit-frame-pointer -DCPU=386 -D__KERNEL__ -DMODULE
+#MODCFLAGS=-O2 -march=i486 -mtune=i686 -fomit-frame-pointer -DCPU=386 -D__KERNEL__ -DMODULE
 # Or this ...
-#MODCFLAGS=-O -fomit-frame-pointer -D__KERNEL__ -DMODULE -DCONFIG_MODVERSIONS
+#MODCFLAGS=-O2 -march=i486 -mtune=i686 -fomit-frame-pointer -D__KERNEL__ -DMODULE -DCONFIG_MODVERSIONS
 
diff -Naur dev86-0.16.17.old/ld/Makefile dev86-0.16.17/ld/Makefile
--- dev86-0.16.17.old/ld/Makefile	2003-10-06 17:14:16.000000000 +0000
+++ dev86-0.16.17/ld/Makefile	2007-11-01 22:42:46.000000000 +0000
@@ -1,6 +1,6 @@
 
 LIBDIR	=/usr/bin
-CFLAGS	=-O
+CFLAGS	=-O2 -march=i486 -mtune=i686
 LDFLAGS	=
 
 # Will need some of these if you want native executables on non-Linux/i386
diff -Naur dev86-0.16.17.old/libbsd/Make.defs dev86-0.16.17/libbsd/Make.defs
--- dev86-0.16.17.old/libbsd/Make.defs	1996-04-23 20:46:59.000000000 +0000
+++ dev86-0.16.17/libbsd/Make.defs	2007-11-01 22:43:31.000000000 +0000
@@ -45,7 +45,7 @@
 endif
 
 CC=bcc $(ARCH)
-CCFLAGS=-O -I -I$(TOP)/libc/include
+CCFLAGS=-O2 -march=i486 -mtune=i686 -I -I$(TOP)/libc/include
 LKFLAGS=-L -L$(TOP)/ -s
 
 else # ifeq ($(PLATFORM),i386-Linux)
@@ -53,7 +53,7 @@
 CC=gcc $(ARCH)
 # ARCH=-b i486-linuxaout
 LKFLAGS=-static -N
-CCFLAGS=-O6 -fomit-frame-pointer -I- -I$(TOP)/include -I. -fno-builtin
+CCFLAGS=-O2 -march=i486 -mtune=i686 -fomit-frame-pointer -I- -I$(TOP)/include -I. -fno-builtin
 WALL=	-ansi -pedantic -Wwrite-strings -Wpointer-arith -Wcast-qual \
 	-Wcast-align -Wtraditional -Wstrict-prototypes -Wmissing-prototypes \
 	-Wnested-externs -Winline -Wshadow
diff -Naur dev86-0.16.17.old/libc/Make.defs dev86-0.16.17/libc/Make.defs
--- dev86-0.16.17.old/libc/Make.defs	2003-11-02 08:02:20.000000000 +0000
+++ dev86-0.16.17/libc/Make.defs	2007-11-01 22:45:12.000000000 +0000
@@ -63,7 +63,7 @@
 LIB_CPU=g386
 LIB_OS=ELKS
 CC=gcc
-CCFLAGS=-O -g -nostdinc -I$(TOP)/include
+CCFLAGS=-O2 -march=i486 -mtune=i686 -g -nostdinc -I$(TOP)/include
 endif
 
 ##############################################################################
diff -Naur dev86-0.16.17.old/libc/regexp/Makefile.org dev86-0.16.17/libc/regexp/Makefile.org
--- dev86-0.16.17.old/libc/regexp/Makefile.org	1996-01-13 13:59:25.000000000 +0000
+++ dev86-0.16.17/libc/regexp/Makefile.org	2007-11-01 22:44:00.000000000 +0000
@@ -18,7 +18,7 @@
 # -p			profiler
 PROF=
 
-CFLAGS=-O $(ENV) $(TEST) $(PROF)
+CFLAGS=-O2 -march=i486 -mtune=i686 $(ENV) $(TEST) $(PROF)
 LINTFLAGS=$(LENV) $(TEST) -ha
 LDFLAGS=-i
 
diff -Naur dev86-0.16.17.old/makefile.in dev86-0.16.17/makefile.in
--- dev86-0.16.17.old/makefile.in	2004-10-02 13:00:53.000000000 +0000
+++ dev86-0.16.17/makefile.in	2007-11-01 22:46:01.000000000 +0000
@@ -42,7 +42,7 @@
 WALL  =-Wall -Wstrict-prototypes
 
 CC	=%CC%
-CFLAGS	=$(GCCFLAG) $(WALL) -O2 -g
+CFLAGS	=$(GCCFLAG) $(WALL) -O2 -march=i486 -mtune=i686 -g
 #endif
 
 #ifndef GNUMAKE
@@ -54,7 +54,7 @@
 # Minix make doesn't understand -C, cc runs out of memory with the headers.
 MAKEC=ash makec
 MAKEX=makec
-CFLAGS=-O -m -w -DPOSIX_HEADERS_MISSING -DVERY_SMALL_MEMORY
+CFLAGS=-O2 -march=i486 -mtune=i686 -m -w -DPOSIX_HEADERS_MISSING -DVERY_SMALL_MEMORY
 #endif
 
 #ifdef __BCC__
@@ -63,7 +63,7 @@
 CFLAGS	=-Ml
 LDFLAGS	=-Ml -s
 #else
-CFLAGS	=-O
+CFLAGS	=-O2 -march=i486 -mtune=i686
 LDFLAGS	=-s -H10000
 BCCARCH =
 #endif
@@ -111,7 +111,7 @@
 
 ##############################################################################
 
-LIBARGS= CC=ncc "CCFLAGS=-O" AR=$(AR) ARFLAGS=$(ARFLAGS)
+LIBARGS= CC=ncc "CCFLAGS=-O" AR=$(AR) ARFLAGS=$(ARFLAGS)
 LIB3ARGS= CC=ncc AR=$(AR) ARFLAGS=$(ARFLAGS)
 
 # Season in the top makefile
diff -Naur dev86-0.16.17.old/mkcompile dev86-0.16.17/mkcompile
--- dev86-0.16.17.old/mkcompile	2002-12-05 00:54:49.000000000 +0000
+++ dev86-0.16.17/mkcompile	2007-11-01 22:46:25.000000000 +0000
@@ -20,7 +20,7 @@
 main() {
    echo    '@echo off'
 
-   CFLAGS='-nologo -O'
+   CFLAGS='-nologo -O2 -march=i486 -mtune=i686'
    LDFLAGS='%LIB%\setargv.obj -link /NOE'
    ARCH=-Ms
    build bcc bcc     bin $SRC_BCC 
diff -Naur dev86-0.16.17.old/tests/Makefile dev86-0.16.17/tests/Makefile
--- dev86-0.16.17.old/tests/Makefile	2004-01-24 10:52:55.000000000 +0000
+++ dev86-0.16.17/tests/Makefile	2007-11-01 22:46:46.000000000 +0000
@@ -4,7 +4,7 @@
 
 BCC=bcc
 CC=$(BCC)
-CFLAGS=-O
+CFLAGS=-O2 -march=i486 -mtune=i686
 
 SRC=env.c ft.c hd.c sync.c compr.c ucomp.c ouch.c lines.c \
     wc.c line2.c rand.c grab.c
diff -Naur dev86-0.16.17.old/unproto/Makefile dev86-0.16.17/unproto/Makefile
--- dev86-0.16.17.old/unproto/Makefile	2003-10-06 17:01:45.000000000 +0000
+++ dev86-0.16.17/unproto/Makefile	2007-11-01 22:47:26.000000000 +0000
@@ -81,11 +81,11 @@
 OBJECTS	= tok_io.o tok_class.o tok_pool.o unproto.o vstring.o symbol.o error.o \
 	hash.o strsave.o
 
-CFLAGS	= -O
+CFLAGS	= -O2 -march=i486 -mtune=i686
 LDFLAGS =
 CCFLAGS = $(CFLAGS) -w $(PIPE) $(SKIP) $(BELL) $(MAP) $(ALIAS) -DREOPEN
 
-#CFLAGS	= -O $(PIPE) $(SKIP) $(BELL) $(MAP) $(ALIAS) -p -Dstatic=
+#CFLAGS	= -O2 -march=i486 -mtune=i686 $(PIPE) $(SKIP) $(BELL) $(MAP) $(ALIAS) -p -Dstatic=
 #CFLAGS	= -g $(PIPE) $(SKIP) $(BELL) $(MAP) $(ALIAS) -DDEBUG
 
 $(PROG): $(OBJECTS)
diff -Naur dev86-0.16.17.old/unproto/Makefile.old dev86-0.16.17/unproto/Makefile.old
--- dev86-0.16.17.old/unproto/Makefile.old	1993-06-18 21:48:17.000000000 +0000
+++ dev86-0.16.17/unproto/Makefile.old	2007-11-01 22:47:57.000000000 +0000
@@ -81,8 +81,8 @@
 OBJECTS	= tok_io.o tok_class.o tok_pool.o unproto.o vstring.o symbol.o error.o \
 	hash.o strsave.o
 
-CFLAGS	= -O $(PIPE) $(SKIP) $(BELL) $(MAP) $(ALIAS)
-#CFLAGS	= -O $(PIPE) $(SKIP) $(BELL) $(MAP) $(ALIAS) -p -Dstatic=
+CFLAGS	= -O2 -march=i486 -mtune=i686 $(PIPE) $(SKIP) $(BELL) $(MAP) $(ALIAS)
+#CFLAGS	= -O2 -march=i486 -mtune=i686 $(PIPE) $(SKIP) $(BELL) $(MAP) $(ALIAS) -p -Dstatic=
 #CFLAGS	= -g $(PIPE) $(SKIP) $(BELL) $(MAP) $(ALIAS) -DDEBUG
 
 $(PROG): $(OBJECTS)