diff --git a/Makefile b/Makefile
index 81f41fd3..b035653a 100644
--- a/Makefile
+++ b/Makefile
@@ -71,7 +71,7 @@ upgrade:
 	go build $(GOFLAGS) -o ./bin/syz-upgrade github.com/google/syzkaller/tools/syz-upgrade
 
 extract: bin/syz-extract
-	LINUX=$(LINUX) LINUXBLD=$(LINUXBLD) ./sys/linux/extract.sh
+	LINUX=$(LINUX) ./sys/linux/extract.sh
 bin/syz-extract:
 	go build $(GOFLAGS) -o $@ ./sys/syz-extract
 
diff --git a/sys/linux/extract.sh b/sys/linux/extract.sh
index 2eb7dd2a..9a5ba45f 100755
--- a/sys/linux/extract.sh
+++ b/sys/linux/extract.sh
@@ -41,36 +41,17 @@ fi
 
 generate_arch() {
 	echo generating arch $1...
-	echo "cd $LINUX; make defconfig"
-	OUT=`(cd $LINUX; make ARCH=$2 CROSS_COMPILE=$3 CFLAGS=$4 defconfig 2>&1)`
-	if [ $? -ne 0 ]; then
-		echo "$OUT"
-		exit 1
-	fi
-	# Without CONFIG_NETFILTER kernel does not build.
-	(cd $LINUX; sed -i "s@# CONFIG_NETFILTER is not set@CONFIG_NETFILTER=y@g" .config)
-	(cd $LINUX; make ARCH=$2 CROSS_COMPILE=$3 CFLAGS=$4 olddefconfig)
-	echo "cd $LINUX; make"
-	OUT=`(cd $LINUX; make ARCH=$2 CROSS_COMPILE=$3 CFLAGS=$4 init/main.o 2>&1)`
-	if [ $? -ne 0 ]; then
-		echo "$OUT"
-		exit 1
-	fi
-	(cd sys/linux; ../../bin/syz-extract -arch $1 -linux "$LINUX" -linuxbld "$LINUXBLD" $FILES)
+	(cd sys/linux; ../../bin/syz-extract -arch $1 -linux "$LINUX" -build $FILES)
 	if [ $? -ne 0 ]; then
 		exit 1
 	fi
 	echo
 }
 
-# $1 Go arch
-# $2 kernel arch
-# $3 cross-compiler prefix
-# $4 CLAGS
-generate_arch amd64 x86_64 x86_64-linux-gnu- "-m64"
-generate_arch arm64 arm64 aarch64-linux-gnu- ""
+generate_arch amd64
+generate_arch arm64
 if [ "$BUILD_FOR_ANDROID" == "no" ]; then
-	generate_arch 386 i386 "" "-m32"
-	generate_arch arm arm arm-linux-gnueabihf- "-march=armv6t2"
-	generate_arch ppc64le powerpc powerpc64le-linux-gnu- ""
+	generate_arch 386
+	generate_arch arm
+	generate_arch ppc64le
 fi
diff --git a/sys/sys.go b/sys/sys.go
index 79683732..1897a635 100644
--- a/sys/sys.go
+++ b/sys/sys.go
@@ -70,6 +70,7 @@ func init() {
 		for arch, target := range archs {
 			target.OS = OS
 			target.Arch = arch
+			target.CrossCFlags = append(target.CrossCFlags, target.CFlags...)
 		}
 	}
 }
diff --git a/sys/syz-extract/extract.go b/sys/syz-extract/extract.go
index d7a2efb9..7a9437e4 100644
--- a/sys/syz-extract/extract.go
+++ b/sys/syz-extract/extract.go
@@ -13,6 +13,7 @@ import (
 	"runtime"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/google/syzkaller/pkg/ast"
 	"github.com/google/syzkaller/pkg/compiler"
@@ -24,6 +25,7 @@ var (
 	flagLinux    = flag.String("linux", "", "path to linux kernel source checkout")
 	flagLinuxBld = flag.String("linuxbld", "", "path to linux kernel build directory")
 	flagArch     = flag.String("arch", "", "arch to generate")
+	flagBuild    = flag.Bool("build", false, "generate arch-specific files in the linux dir")
 )
 
 type File struct {
@@ -33,11 +35,6 @@ type File struct {
 }
 
 func main() {
-	failf := func(msg string, args ...interface{}) {
-		fmt.Fprintf(os.Stderr, msg+"\n", args...)
-		os.Exit(1)
-	}
-
 	flag.Parse()
 	if *flagLinux == "" {
 		failf("provide path to linux kernel checkout via -linux flag (or make extract LINUX= flag)")
@@ -56,6 +53,9 @@ func main() {
 	if n == 0 {
 		failf("usage: syz-extract -linux=/linux/checkout -arch=arch input_file.txt...")
 	}
+	if *flagBuild {
+		buildKernel(target, *flagLinux)
+	}
 
 	files := make([]File, n)
 	inc := make(chan *File, n)
@@ -120,3 +120,37 @@ func processFile(target *sys.Target, inname string) (map[string]bool, error) {
 	}
 	return undeclared, nil
 }
+
+func buildKernel(target *sys.Target, dir string) {
+	// TODO(dvyukov): use separate temp build dir.
+	// This will allow to do build for all archs in parallel and
+	// won't destroy user's build state.
+	makeArgs := []string{
+		"ARCH=" + target.KernelArch,
+		"CROSS_COMPILE=" + target.CCompilerPrefix,
+		"CFLAGS=" + strings.Join(target.CrossCFlags, " "),
+	}
+	out, err := osutil.RunCmd(time.Hour, dir, "make", append(makeArgs, "defconfig")...)
+	if err != nil {
+		failf("make defconfig failed: %v\n%s\n", err, out)
+	}
+	// Without CONFIG_NETFILTER kernel does not build.
+	out, err = osutil.RunCmd(time.Minute, dir, "sed", "-i",
+		"s@# CONFIG_NETFILTER is not set@CONFIG_NETFILTER=y@g", ".config")
+	if err != nil {
+		failf("sed .config failed: %v\n%s\n", err, out)
+	}
+	out, err = osutil.RunCmd(time.Hour, dir, "make", append(makeArgs, "olddefconfig")...)
+	if err != nil {
+		failf("make olddefconfig failed: %v\n%s\n", err, out)
+	}
+	out, err = osutil.RunCmd(time.Hour, dir, "make", append(makeArgs, "init/main.o")...)
+	if err != nil {
+		failf("make failed: %v\n%s\n", err, out)
+	}
+}
+
+func failf(msg string, args ...interface{}) {
+	fmt.Fprintf(os.Stderr, msg+"\n", args...)
+	os.Exit(1)
+}