diff --git a/scripts/buildall b/scripts/buildall
index 63ba2988..81101eff 100755
--- a/scripts/buildall
+++ b/scripts/buildall
@@ -1,25 +1,17 @@
-#!/bin/sh
+#!/usr/bin/env bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 # build everything in the projects directory
-PROJECTS=`echo project/*.mk | xargs -n1 basename | sed 's/\.mk//'`
+PROJECTS=$(echo project/*.mk | xargs -n1 basename | sed 's/\.mk//')
 FAILED=""
 
-case `uname` in
-Linux)
-	N=`cat /proc/cpuinfo | grep processor | wc -l`
-	PARALLEL=-j`expr $N + $N`
-	;;
-*)
-	PARALLEL=-j4
-	;;
-esac
-
 for p in $PROJECTS; do
-	PROJECT=$p nice make $PARALLEL || FAILED="$FAILED $p"
+    PROJECT=$p nice $DIR/make-parallel || FAILED="$FAILED $p"
 done
 
 if [ "$FAILED" != "" ]; then
-	echo
-	echo some projects have failed to build:
-	echo $FAILED
+    echo
+    echo some projects have failed to build:
+    echo $FAILED
 fi
diff --git a/scripts/do-armemu-test b/scripts/do-armemu-test
index 04c9e50a..7bd9b8bb 100755
--- a/scripts/do-armemu-test
+++ b/scripts/do-armemu-test
@@ -1,4 +1,6 @@
-#!/bin/sh
+#!/usr/bin/env bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 export PROJECT=armemu-test
 
@@ -6,6 +8,6 @@ if [ ! -f blk.bin ]; then
 	dd if=/dev/zero of=blk.bin bs=1024k count=16
 fi
 
-make -j8 -C ../armemu &&
-make -j8 &&
+$DIR/make-parallel -C ../armemu &&
+$DIR/make-parallel &&
 (cd build-$PROJECT; ../../armemu/build-generic/armemu)
diff --git a/scripts/do-or1ksim b/scripts/do-or1ksim
index 421c316e..6da571f8 100755
--- a/scripts/do-or1ksim
+++ b/scripts/do-or1ksim
@@ -1,4 +1,6 @@
-#!/bin/sh
+#!/usr/bin/env bash
 
-make or1ksim -j4 &&
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+$DIR/make-parallel or1ksim &&
 or1k-elf-sim -f platform/or1ksim/or1ksim.cfg build-or1ksim/lk.elf $@
diff --git a/scripts/do-osk5912-test b/scripts/do-osk5912-test
deleted file mode 100755
index 175d1029..00000000
--- a/scripts/do-osk5912-test
+++ /dev/null
@@ -1,6 +0,0 @@
-#!/bin/sh
-
-export PROJECT=osk5912-test
-
-make && 
-scp build-osk5912-test/lk.bin four:/tftproot
diff --git a/scripts/do-qemuarm b/scripts/do-qemuarm
index ec985bab..bc579c1d 100755
--- a/scripts/do-qemuarm
+++ b/scripts/do-qemuarm
@@ -1,4 +1,6 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 function HELP {
     echo "help:"
@@ -95,6 +97,6 @@ elif [ $DO_MINIHEAP == 1 ]; then
 	MAKE_VARS=LK_HEAP_IMPLEMENTATION=miniheap
 fi
 
-make $MAKE_VARS $PROJECT -j4 &&
+$DIR/make-parallel $MAKE_VARS $PROJECT &&
 echo $SUDO $QEMU $ARGS $@ &&
 $SUDO $QEMU $ARGS $@
diff --git a/scripts/do-qemum4 b/scripts/do-qemum4
index c776657a..3661b36e 100755
--- a/scripts/do-qemum4
+++ b/scripts/do-qemum4
@@ -1,5 +1,7 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
 DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
 DEFAULT_TOOLPATH="$DIR/toolpaths.default"
 if [ -e "$DEFAULT_TOOLPATH" ]
 then
@@ -53,6 +55,6 @@ elif [ $DO_MINIHEAP == 1 ]; then
 	MAKE_VARS=LK_HEAP_IMPLEMENTATION=miniheap
 fi
 
-make $MAKE_VARS $PROJECT -j4 &&
+$DIR/make-parallel $MAKE_VARS $PROJECT &&
 echo $QEMUM4 $ARGS $@ &&
 $QEMUM4 $ARGS $@
diff --git a/scripts/do-qemumicroblaze b/scripts/do-qemumicroblaze
index 384ae99a..e752404a 100755
--- a/scripts/do-qemumicroblaze
+++ b/scripts/do-qemumicroblaze
@@ -1,4 +1,9 @@
-#!/bin/sh
+#!/usr/bin/env bash
 
-make qemu-microblaze-test -j4 &&
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+set -e
+set -x
+
+$DIR/make-parallel qemu-microblaze-test
 qemu-system-microblaze -kernel build-qemu-microblaze-test/lk.elf -nographic $@
diff --git a/scripts/do-qemumips b/scripts/do-qemumips
index 84db33a4..4f230b70 100755
--- a/scripts/do-qemumips
+++ b/scripts/do-qemumips
@@ -1,4 +1,9 @@
-#!/bin/sh
+#!/usr/bin/env bash
 
-make qemu-mips-test -j4 &&
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+set -e
+set -x
+
+$DIR/make-parallel qemu-mips-test
 qemu-system-mips -machine mips -cpu M14K -kernel build-qemu-mips-test/lk.elf -nographic $@
diff --git a/scripts/do-qemuriscv32 b/scripts/do-qemuriscv32
index bc2f0a17..d2226698 100755
--- a/scripts/do-qemuriscv32
+++ b/scripts/do-qemuriscv32
@@ -1,4 +1,9 @@
-#!/bin/sh
+#!/usr/bin/env bash
 
-make sifive-e-test -j4 &&
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+set -e
+set -x
+
+$DIR/make-parallel sifive-e-test
 qemu-system-riscv32 -machine sifive_e -kernel build-sifive-e-test/lk.elf -nographic $@
diff --git a/scripts/do-qemux86 b/scripts/do-qemux86
index 0b85fbee..5b3f8e80 100755
--- a/scripts/do-qemux86
+++ b/scripts/do-qemux86
@@ -1,4 +1,6 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 function HELP {
     echo "help:"
@@ -79,7 +81,7 @@ if (( $DO_KVM )); then
     ARGS+=" -enable-kvm -cpu host"
 fi
 
-make $MAKE_VARS $PROJECT -j4 &&
+$DIR/make-parallel $MAKE_VARS $PROJECT &&
 echo $SUDO $QEMU $ARGS $@ &&
 $SUDO $QEMU $ARGS $@
 
diff --git a/scripts/do-sifive-e b/scripts/do-sifive-e
index d4b6110c..6b4df718 100755
--- a/scripts/do-sifive-e
+++ b/scripts/do-sifive-e
@@ -1,13 +1,14 @@
 #!/usr/bin/env bash
 
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
 set -x
 set -e
 
-
 export PROJECT=sifive-e-test
 TARGET=`pwd`/build-${PROJECT}/lk.elf
 
-make -j4
+$DIR/make-parallel
 
 SDK_DIR=${HOME}/src/freedom-e-sdk
 OPENOCD_DIR=${SDK_DIR}/riscv-openocd-0.10.0-2018.12.0-x86_64-linux-ubuntu14/bin
diff --git a/scripts/do-stellaris-launchpad-test b/scripts/do-stellaris-launchpad-test
index 5230ad5d..26619ba3 100755
--- a/scripts/do-stellaris-launchpad-test
+++ b/scripts/do-stellaris-launchpad-test
@@ -1,6 +1,8 @@
-#!/bin/sh
+#!/usr/bin/env bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 export PROJECT=stellaris-launchpad-test
 
-make -j8 &&
+$DIR/make-parallel &&
 lm4flash -v build-$PROJECT/lk.bin
diff --git a/scripts/do-stm32f7-disco-test b/scripts/do-stm32f7-disco-test
index b947e54a..a43cb0a9 100755
--- a/scripts/do-stm32f7-disco-test
+++ b/scripts/do-stm32f7-disco-test
@@ -1,7 +1,9 @@
-#!/bin/sh
+#!/usr/bin/env bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 export PROJECT=stm32f746g-disco-test
 
-make -j8 &&
+$DIR/make-parallel &&
 openocd -f interface/stlink-v2-1.cfg -f board/stm32756g_eval.cfg \
     -c "program build-$PROJECT/lk.bin reset exit 0x08000000"
diff --git a/scripts/do-uzed-xmd b/scripts/do-uzed-xmd
index e94f1adb..cd50de75 100755
--- a/scripts/do-uzed-xmd
+++ b/scripts/do-uzed-xmd
@@ -1,6 +1,8 @@
-#!/bin/sh
+#!/usr/bin/env bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 PROJECT=uzed-test
 
-make $PROJECT -j &&
+$DIR/make-parallel $PROJECT &&
 xmd -tcl scripts/xmd.tcl $PROJECT
diff --git a/scripts/do-zybo-xmd b/scripts/do-zybo-xmd
index 2481eb51..6f93a047 100755
--- a/scripts/do-zybo-xmd
+++ b/scripts/do-zybo-xmd
@@ -1,6 +1,8 @@
-#!/bin/sh
+#!/usr/bin/env bash
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 PROJECT=zybo-test
 
-make $PROJECT -j &&
+$DIR/make-parallel $PROJECT -j &&
 xmd -tcl scripts/xmd.tcl $PROJECT
diff --git a/scripts/make-parallel b/scripts/make-parallel
new file mode 100755
index 00000000..9740150f
--- /dev/null
+++ b/scripts/make-parallel
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+# Copyright 2016 The Fuchsia Authors
+#
+# Use of this source code is governed by a MIT-style
+# license that can be found in the LICENSE file or at
+# https://opensource.org/licenses/MIT
+MAKE=make
+case `uname` in
+Linux)
+    N=`cat /proc/cpuinfo | grep processor | wc -l`
+    PARALLEL=-j`expr $N + $N`
+    ;;
+Darwin)
+    PARALLEL=-j`sysctl -n hw.ncpu`
+    ;;
+FreeBSD)
+    PARALLEL=-j`sysctl -n hw.ncpu`
+    MAKE=gmake
+    ;;
+*)
+    PARALLEL=-j8
+    ;;
+esac
+exec $MAKE $PARALLEL "$@"
diff --git a/scripts/toolpaths.default b/scripts/toolpaths.default
index ad9570ce..5a66667c 100644
--- a/scripts/toolpaths.default
+++ b/scripts/toolpaths.default
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 LOCAL_TOOLPATH="$DIR/toolpaths.local"