diff --git a/README.md b/README.md
index e9150a628..c57682e34 100644
--- a/README.md
+++ b/README.md
@@ -6,8 +6,8 @@
 [![Join the chat at https://gitter.im/termux/termux](https://badges.gitter.im/termux/termux.svg)](https://gitter.im/termux/termux)
 
 This project contains scripts and patches to build packages for the
-[Termux](https://termux.com/) Android application. Note that packages are
-cross-compiled and on-device builds are not currently supported.
+[Termux](https://termux.com/) Android application. Note that on-device
+package building is supported only partially for now.
 
 More information can be found in the [docs](docs/) directory.
 
diff --git a/build-all.sh b/build-all.sh
index 4137e5b0e..9b0dc0f9f 100755
--- a/build-all.sh
+++ b/build-all.sh
@@ -3,6 +3,11 @@
 
 set -e -u -o pipefail
 
+if [ "$(uname -o)" = "Android" ] || [ -e "/system/bin/app_process" ]; then
+	echo "On-device execution of this script is not supported."
+	exit 1
+fi
+
 # Read settings from .termuxrc if existing
 test -f $HOME/.termuxrc && . $HOME/.termuxrc
 : ${TERMUX_TOPDIR:="$HOME/.termux-build"}
diff --git a/build-package.sh b/build-package.sh
index 35d53418f..22d269557 100755
--- a/build-package.sh
+++ b/build-package.sh
@@ -3,15 +3,26 @@
 
 set -e -o pipefail -u
 
-# Utility function to log an error message and exit with an error code.
-source scripts/build/termux_error_exit.sh
-
-if [ "$(uname -o)" = Android ]; then
-	termux_error_exit "On-device builds are not supported - see README.md"
+: "${TMPDIR:=/tmp}"
+export TMPDIR
+
+if [ "$(uname -o)" = "Android" ] || [ -e "/system/bin/app_process" ]; then
+	if [ "$(id -u)" = "0" ]; then
+		echo "On-device execution of this script as root is disabled."
+		exit 1
+	fi
+
+	export TERMUX_ARCH=$(dpkg --print-architecture)
+
+	# This variable tells all parts of build system that build
+	# is performed on device.
+	export TERMUX_ON_DEVICE_BUILD=true
+else
+	export TERMUX_ON_DEVICE_BUILD=
 fi
 
 # Lock file to prevent parallel running in the same environment.
-TERMUX_BUILD_LOCK_FILE="/tmp/.termux-build.lck"
+TERMUX_BUILD_LOCK_FILE="${TMPDIR}/.termux-build.lck"
 if [ ! -e "$TERMUX_BUILD_LOCK_FILE" ]; then
 	touch "$TERMUX_BUILD_LOCK_FILE"
 fi
@@ -20,6 +31,9 @@ fi
 # lock file.
 : "${TERMUX_BUILD_IGNORE_LOCK:=false}"
 
+# Utility function to log an error message and exit with an error code.
+source scripts/build/termux_error_exit.sh
+
 # Utility function to download a resource with an expected checksum.
 source scripts/build/termux_download.sh
 
@@ -151,13 +165,16 @@ source scripts/build/termux_step_finish_build.sh
 ################################################################################
 
 _show_usage() {
-    echo "Usage: ./build-package.sh [-a ARCH] [-d] [-D] [-f] [-i] [-I] [-q] [-s] [-o DIR] PACKAGE_1 PACKAGE_2 ..."
+    echo "Usage: ./build-package.sh [options] PACKAGE_1 PACKAGE_2 ..."
+    echo
     echo "Build a package by creating a .deb file in the debs/ folder."
-    echo "  -a The architecture to build for: aarch64(default), arm, i686, x86_64 or all."
+    echo
+    echo "Available options:"
+    [ -z "$TERMUX_ON_DEVICE_BUILD" ] && echo "  -a The architecture to build for: aarch64(default), arm, i686, x86_64 or all."
     echo "  -d Build with debug symbols."
     echo "  -D Build a disabled package in disabled-packages/."
     echo "  -f Force build even if package has already been built."
-    echo "  -i Download and extract dependencies instead of building them."
+    [ -z "$TERMUX_ON_DEVICE_BUILD" ] && echo "  -i Download and extract dependencies instead of building them."
     echo "  -I Download and extract dependencies instead of building them, keep existing /data/data/com.termux files."
     echo "  -q Quiet build."
     echo "  -s Skip dependency check."
@@ -167,12 +184,24 @@ _show_usage() {
 
 while getopts :a:hdDfiIqso: option; do
 	case "$option" in
-		a) TERMUX_ARCH="$OPTARG";;
+		a)
+			if [ -n "$TERMUX_ON_DEVICE_BUILD" ]; then
+				termux_error_exit "./build-package.sh: option '-a' is not available for on-device builds"
+			else
+				export TERMUX_ARCH="$OPTARG"
+			fi
+			;;
 		h) _show_usage;;
 		d) export TERMUX_DEBUG=true;;
 		D) local TERMUX_IS_DISABLED=true;;
 		f) TERMUX_FORCE_BUILD=true;;
-		i) export TERMUX_INSTALL_DEPS=true;;
+		i)
+			if [ -n "$TERMUX_ON_DEVICE_BUILD" ]; then
+				termux_error_exit "./build-package.sh: option '-i' is not available for on-device builds"
+			else
+				export TERMUX_INSTALL_DEPS=true
+			fi
+			;;
 		I) export TERMUX_INSTALL_DEPS=true && export TERMUX_NO_CLEAN=true;;
 		q) export TERMUX_QUIET_BUILD=true;;
 		s) export TERMUX_SKIP_DEPCHECK=true;;
@@ -197,11 +226,11 @@ while (($# > 0)); do
 		fi
 
 		# Handle 'all' arch:
-		if [ -n "${TERMUX_ARCH+x}" ] && [ "${TERMUX_ARCH}" = 'all' ]; then
+		if [ -z "$TERMUX_ON_DEVICE_BUILD" ] && [ -n "${TERMUX_ARCH+x}" ] && [ "${TERMUX_ARCH}" = 'all' ]; then
 			for arch in 'aarch64' 'arm' 'i686' 'x86_64'; do
-				TERMUX_BUILD_IGNORE_LOCK=true ./build-package.sh ${TERMUX_FORCE_BUILD+-f} \
-					-a $arch ${TERMUX_INSTALL_DEPS+-i} ${TERMUX_IS_DISABLED+-D} ${TERMUX_DEBUG+-d} \
-					${TERMUX_DEBDIR+-o $TERMUX_DEBDIR} "$1"
+				env TERMUX_ARCH="$arch" TERMUX_BUILD_IGNORE_LOCK=true ./build-package.sh \
+					${TERMUX_FORCE_BUILD+-f} ${TERMUX_INSTALL_DEPS+-i} ${TERMUX_IS_DISABLED+-D} \
+					${TERMUX_DEBUG+-d} ${TERMUX_DEBDIR+-o $TERMUX_DEBDIR} "$1"
 			done
 			exit
 		fi
diff --git a/clean.sh b/clean.sh
index b00e19220..67da1666e 100755
--- a/clean.sh
+++ b/clean.sh
@@ -2,13 +2,28 @@
 # clean.sh - clean everything.
 set -e -u
 
-# Read settings from .termuxrc if existing
-test -f $HOME/.termuxrc && . $HOME/.termuxrc
-: ${TERMUX_TOPDIR:="$HOME/.termux-build"}
+# Checking if script is running on Android with 2 different methods.
+# Needed for safety to prevent execution of potentially dangerous
+# operations such as 'rm -rf /data/*' on Android device.
+if [ "$(uname -o)" = "Android" ] || [ -e "/system/bin/app_process" ]; then
+	TERMUX_ON_DEVICE_BUILD=true
+else
+	TERMUX_ON_DEVICE_BUILD=
+fi
 
+if [ "$(id -u)" = "0" ] && [ -n "$TERMUX_ON_DEVICE_BUILD" ]; then
+	echo "On-device execution of this script as root is disabled."
+	exit 1
+fi
+
+# Read settings from .termuxrc if existing
+test -f "$HOME/.termuxrc" && . "$HOME/.termuxrc"
+: "${TERMUX_TOPDIR:="$HOME/.termux-build"}"
+: "${TMPDIR:=/tmp}"
+export TMPDIR
 
 # Lock file. Same as used in build-package.sh.
-TERMUX_BUILD_LOCK_FILE="/tmp/.termux-build.lck"
+TERMUX_BUILD_LOCK_FILE="${TMPDIR}/.termux-build.lck"
 if [ ! -e "$TERMUX_BUILD_LOCK_FILE" ]; then
 	touch "$TERMUX_BUILD_LOCK_FILE"
 fi
@@ -20,7 +35,13 @@ fi
 	fi
 
 	if [ -d "$TERMUX_TOPDIR" ]; then
-		chmod +w -R $TERMUX_TOPDIR
+		chmod +w -R "$TERMUX_TOPDIR"
+	fi
+
+	if [ -n "$TERMUX_ON_DEVICE_BUILD" ]; then
+		# For on-device build cleanup /data shouldn't be erased.
+		rm -Rf "$TERMUX_TOPDIR"
+	else
+		rm -Rf /data/* "$TERMUX_TOPDIR"
 	fi
-	rm -Rf /data/* $TERMUX_TOPDIR
 } 5< "$TERMUX_BUILD_LOCK_FILE"
diff --git a/scripts/build/configure/termux_step_configure_autotools.sh b/scripts/build/configure/termux_step_configure_autotools.sh
index df1d289db..c9bac5053 100644
--- a/scripts/build/configure/termux_step_configure_autotools.sh
+++ b/scripts/build/configure/termux_step_configure_autotools.sh
@@ -32,12 +32,14 @@ termux_step_configure_autotools() {
 		QUIET_BUILD="--enable-silent-rules --silent --quiet"
 	fi
 
-	# Some packages provides a $PKG-config script which some configure scripts pickup instead of pkg-config:
-	mkdir "$TERMUX_PKG_TMPDIR/config-scripts"
-	for f in $TERMUX_PREFIX/bin/*config; do
-		test -f "$f" && cp "$f" "$TERMUX_PKG_TMPDIR/config-scripts"
-	done
-	export PATH=$TERMUX_PKG_TMPDIR/config-scripts:$PATH
+	if [ -z "$TERMUX_ON_DEVICE_BUILD" ]; then
+		# Some packages provides a $PKG-config script which some configure scripts pickup instead of pkg-config:
+		mkdir "$TERMUX_PKG_TMPDIR/config-scripts"
+		for f in $TERMUX_PREFIX/bin/*config; do
+			test -f "$f" && cp "$f" "$TERMUX_PKG_TMPDIR/config-scripts"
+		done
+		export PATH=$TERMUX_PKG_TMPDIR/config-scripts:$PATH
+	fi
 
 	# Avoid gnulib wrapping of functions when cross compiling. See
 	# http://wiki.osdev.org/Cross-Porting_Software#Gnulib
diff --git a/scripts/build/configure/termux_step_configure_cmake.sh b/scripts/build/configure/termux_step_configure_cmake.sh
index 617ff8ef6..eb6f89d3a 100644
--- a/scripts/build/configure/termux_step_configure_cmake.sh
+++ b/scripts/build/configure/termux_step_configure_cmake.sh
@@ -1,7 +1,6 @@
 termux_step_configure_cmake() {
 	termux_setup_cmake
 
-	local TOOLCHAIN_ARGS="-DCMAKE_ANDROID_STANDALONE_TOOLCHAIN=$TERMUX_STANDALONE_TOOLCHAIN"
 	local BUILD_TYPE=MinSizeRel
 	test -n "$TERMUX_DEBUG" && BUILD_TYPE=Debug
 
@@ -14,33 +13,45 @@ termux_step_configure_cmake() {
 	else
 		MAKE_PROGRAM_PATH=$(which make)
 	fi
-	CFLAGS+=" --target=$CCTERMUX_HOST_PLATFORM -fno-addrsig"
-	CXXFLAGS+=" --target=$CCTERMUX_HOST_PLATFORM -fno-addrsig"
-	LDFLAGS+=" --target=$CCTERMUX_HOST_PLATFORM"
+
+	CXXFLAGS+=" -fno-addrsig"
+	CFLAGS+=" -fno-addrsig"
+
+	local CMAKE_ADDITIONAL_ARGS=()
+	if [ -z "$TERMUX_ON_DEVICE_BUILD" ]; then
+		CXXFLAGS+=" --target=$CCTERMUX_HOST_PLATFORM"
+		CFLAGS+=" --target=$CCTERMUX_HOST_PLATFORM"
+		LDFLAGS+=" --target=$CCTERMUX_HOST_PLATFORM"
+
+		CMAKE_ADDITIONAL_ARGS+=("-DCMAKE_CROSSCOMPILING=True")
+		CMAKE_ADDITIONAL_ARGS+=("-DCMAKE_LINKER=$TERMUX_STANDALONE_TOOLCHAIN/bin/$LD $LDFLAGS")
+		CMAKE_ADDITIONAL_ARGS+=("-DCMAKE_SYSTEM_NAME=Android")
+		CMAKE_ADDITIONAL_ARGS+=("-DCMAKE_SYSTEM_VERSION=$TERMUX_PKG_API_LEVEL")
+		CMAKE_ADDITIONAL_ARGS+=("-DCMAKE_SYSTEM_PROCESSOR=$CMAKE_PROC")
+		CMAKE_ADDITIONAL_ARGS+=("-DCMAKE_ANDROID_STANDALONE_TOOLCHAIN=$TERMUX_STANDALONE_TOOLCHAIN")
+	else
+		CMAKE_ADDITIONAL_ARGS+=("-DCMAKE_LINKER=$(which $LD) $LDFLAGS")
+	fi
 
 	# XXX: CMAKE_{AR,RANLIB} needed for at least jsoncpp build to not
-	# pick up cross compiled binutils tool in $PREFIX/bin:
+	# pick up cross compiled binutils tool in $TERMUX_PREFIX/bin:
 	cmake -G "$TERMUX_CMAKE_BUILD" "$TERMUX_PKG_SRCDIR" \
 		-DCMAKE_AR="$(which $AR)" \
 		-DCMAKE_UNAME="$(which uname)" \
 		-DCMAKE_RANLIB="$(which $RANLIB)" \
 		-DCMAKE_BUILD_TYPE=$BUILD_TYPE \
-		-DCMAKE_CROSSCOMPILING=True \
 		-DCMAKE_C_FLAGS="$CFLAGS $CPPFLAGS" \
 		-DCMAKE_CXX_FLAGS="$CXXFLAGS $CPPFLAGS" \
-		-DCMAKE_LINKER="$TERMUX_STANDALONE_TOOLCHAIN/bin/$LD $LDFLAGS" \
 		-DCMAKE_FIND_ROOT_PATH=$TERMUX_PREFIX \
 		-DCMAKE_FIND_ROOT_PATH_MODE_PROGRAM=NEVER \
 		-DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY \
 		-DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY=ONLY \
 		-DCMAKE_INSTALL_PREFIX=$TERMUX_PREFIX \
 		-DCMAKE_MAKE_PROGRAM=$MAKE_PROGRAM_PATH \
-		-DCMAKE_SYSTEM_PROCESSOR=$CMAKE_PROC \
-		-DCMAKE_SYSTEM_NAME=Android \
-		-DCMAKE_SYSTEM_VERSION=$TERMUX_PKG_API_LEVEL \
 		-DCMAKE_SKIP_INSTALL_RPATH=ON \
 		-DCMAKE_USE_SYSTEM_LIBRARIES=True \
 		-DDOXYGEN_EXECUTABLE= \
 		-DBUILD_TESTING=OFF \
-		$TERMUX_PKG_EXTRA_CONFIGURE_ARGS $TOOLCHAIN_ARGS
+		"${CMAKE_ADDITIONAL_ARGS[@]}" \
+		$TERMUX_PKG_EXTRA_CONFIGURE_ARGS
 }
diff --git a/scripts/build/setup/termux_setup_cmake.sh b/scripts/build/setup/termux_setup_cmake.sh
index f4f50f20a..aa19e1595 100644
--- a/scripts/build/setup/termux_setup_cmake.sh
+++ b/scripts/build/setup/termux_setup_cmake.sh
@@ -5,15 +5,33 @@ termux_setup_cmake() {
 	local TERMUX_CMAKE_TARNAME=cmake-${TERMUX_CMAKE_VERSION}-Linux-x86_64.tar.gz
 	local TERMUX_CMAKE_TARFILE=$TERMUX_PKG_TMPDIR/$TERMUX_CMAKE_TARNAME
 	local TERMUX_CMAKE_FOLDER=$TERMUX_COMMON_CACHEDIR/cmake-$TERMUX_CMAKE_VERSION
-	if [ ! -d "$TERMUX_CMAKE_FOLDER" ]; then
-		termux_download https://cmake.org/files/v$TERMUX_CMAKE_MAJORVESION/$TERMUX_CMAKE_TARNAME \
+
+	if [ -z "$TERMUX_ON_DEVICE_BUILD" ]; then
+		if [ ! -d "$TERMUX_CMAKE_FOLDER" ]; then
+			termux_download https://cmake.org/files/v$TERMUX_CMAKE_MAJORVESION/$TERMUX_CMAKE_TARNAME \
 				"$TERMUX_CMAKE_TARFILE" \
 				757e7ddd29d11422334a60d7cd9c19b7af20349a03cb15aa3c879f1b54193c95
-		rm -Rf "$TERMUX_PKG_TMPDIR/cmake-${TERMUX_CMAKE_VERSION}-Linux-x86_64"
-		tar xf "$TERMUX_CMAKE_TARFILE" -C "$TERMUX_PKG_TMPDIR"
-		mv "$TERMUX_PKG_TMPDIR/cmake-${TERMUX_CMAKE_VERSION}-Linux-x86_64" \
-		   "$TERMUX_CMAKE_FOLDER"
+			rm -Rf "$TERMUX_PKG_TMPDIR/cmake-${TERMUX_CMAKE_VERSION}-Linux-x86_64"
+			tar xf "$TERMUX_CMAKE_TARFILE" -C "$TERMUX_PKG_TMPDIR"
+			mv "$TERMUX_PKG_TMPDIR/cmake-${TERMUX_CMAKE_VERSION}-Linux-x86_64" \
+				"$TERMUX_CMAKE_FOLDER"
+		fi
+
+		export PATH=$TERMUX_CMAKE_FOLDER/bin:$PATH
+	else
+		if [ "$(dpkg-query -W -f '${db:Status-Status}\n' cmake 2>/dev/null)" != "installed" ]; then
+			echo "Package 'cmake' is not installed."
+			echo "You can install it with"
+			echo
+			echo "  pkg install cmake"
+			echo
+			echo "or build it from source with"
+			echo
+			echo "  ./build-package.sh cmake"
+			echo
+			exit 1
+		fi
 	fi
-	export PATH=$TERMUX_CMAKE_FOLDER/bin:$PATH
+
 	export CMAKE_INSTALL_ALWAYS=1
 }
diff --git a/scripts/build/setup/termux_setup_golang.sh b/scripts/build/setup/termux_setup_golang.sh
index 7423bcd6f..bcca976f1 100644
--- a/scripts/build/setup/termux_setup_golang.sh
+++ b/scripts/build/setup/termux_setup_golang.sh
@@ -19,20 +19,35 @@ termux_setup_golang() {
 		termux_error_exit "Unsupported arch: $TERMUX_ARCH"
 	fi
 
-	local TERMUX_GO_VERSION=go1.12.7
-	local TERMUX_GO_PLATFORM=linux-amd64
+	if [ -z "$TERMUX_ON_DEVICE_BUILD" ]; then
+		local TERMUX_GO_VERSION=go1.12.7
+		local TERMUX_GO_PLATFORM=linux-amd64
 
-	local TERMUX_BUILDGO_FOLDER=$TERMUX_COMMON_CACHEDIR/${TERMUX_GO_VERSION}
-	export GOROOT=$TERMUX_BUILDGO_FOLDER
-	export PATH=$GOROOT/bin:$PATH
+		local TERMUX_BUILDGO_FOLDER=$TERMUX_COMMON_CACHEDIR/${TERMUX_GO_VERSION}
+		export GOROOT=$TERMUX_BUILDGO_FOLDER
+		export PATH=$GOROOT/bin:$PATH
 
-	if [ -d "$TERMUX_BUILDGO_FOLDER" ]; then return; fi
+		if [ -d "$TERMUX_BUILDGO_FOLDER" ]; then return; fi
 
-	local TERMUX_BUILDGO_TAR=$TERMUX_COMMON_CACHEDIR/${TERMUX_GO_VERSION}.${TERMUX_GO_PLATFORM}.tar.gz
-	rm -Rf "$TERMUX_COMMON_CACHEDIR/go" "$TERMUX_BUILDGO_FOLDER"
-	termux_download https://storage.googleapis.com/golang/${TERMUX_GO_VERSION}.${TERMUX_GO_PLATFORM}.tar.gz \
-		"$TERMUX_BUILDGO_TAR" \
-		66d83bfb5a9ede000e33c6579a91a29e6b101829ad41fffb5c5bb6c900e109d9
+		local TERMUX_BUILDGO_TAR=$TERMUX_COMMON_CACHEDIR/${TERMUX_GO_VERSION}.${TERMUX_GO_PLATFORM}.tar.gz
+		rm -Rf "$TERMUX_COMMON_CACHEDIR/go" "$TERMUX_BUILDGO_FOLDER"
+		termux_download https://storage.googleapis.com/golang/${TERMUX_GO_VERSION}.${TERMUX_GO_PLATFORM}.tar.gz \
+			"$TERMUX_BUILDGO_TAR" \
+			66d83bfb5a9ede000e33c6579a91a29e6b101829ad41fffb5c5bb6c900e109d9
 
-	( cd "$TERMUX_COMMON_CACHEDIR"; tar xf "$TERMUX_BUILDGO_TAR"; mv go "$TERMUX_BUILDGO_FOLDER"; rm "$TERMUX_BUILDGO_TAR" )
+		( cd "$TERMUX_COMMON_CACHEDIR"; tar xf "$TERMUX_BUILDGO_TAR"; mv go "$TERMUX_BUILDGO_FOLDER"; rm "$TERMUX_BUILDGO_TAR" )
+	else
+		if [ "$(dpkg-query -W -f '${db:Status-Status}\n' golang 2>/dev/null)" != "installed" ]; then
+			echo "Package 'golang' is not installed."
+			echo "You can install it with"
+			echo
+			echo "  pkg install golang"
+			echo
+			echo "or build it from source with"
+			echo
+			echo "  ./build-package.sh golang"
+			echo
+			exit 1
+		fi
+	fi
 }
diff --git a/scripts/build/setup/termux_setup_ninja.sh b/scripts/build/setup/termux_setup_ninja.sh
index 9b8a0a957..eb95bf01b 100644
--- a/scripts/build/setup/termux_setup_ninja.sh
+++ b/scripts/build/setup/termux_setup_ninja.sh
@@ -1,14 +1,30 @@
 termux_setup_ninja() {
 	local NINJA_VERSION=1.9.0
 	local NINJA_FOLDER=$TERMUX_COMMON_CACHEDIR/ninja-$NINJA_VERSION
-	if [ ! -x "$NINJA_FOLDER/ninja" ]; then
-		mkdir -p "$NINJA_FOLDER"
-		local NINJA_ZIP_FILE=$TERMUX_PKG_TMPDIR/ninja-$NINJA_VERSION.zip
-		termux_download https://github.com/ninja-build/ninja/releases/download/v$NINJA_VERSION/ninja-linux.zip \
-			"$NINJA_ZIP_FILE" \
-			1b1235f2b0b4df55ac6d80bbe681ea3639c9d2c505c7ff2159a3daf63d196305
-		unzip "$NINJA_ZIP_FILE" -d "$NINJA_FOLDER"
-		chmod 755 $NINJA_FOLDER/ninja
+
+	if [ -z "$TERMUX_ON_DEVICE_BUILD" ]; then
+		if [ ! -x "$NINJA_FOLDER/ninja" ]; then
+			mkdir -p "$NINJA_FOLDER"
+			local NINJA_ZIP_FILE=$TERMUX_PKG_TMPDIR/ninja-$NINJA_VERSION.zip
+			termux_download https://github.com/ninja-build/ninja/releases/download/v$NINJA_VERSION/ninja-linux.zip \
+				"$NINJA_ZIP_FILE" \
+				1b1235f2b0b4df55ac6d80bbe681ea3639c9d2c505c7ff2159a3daf63d196305
+			unzip "$NINJA_ZIP_FILE" -d "$NINJA_FOLDER"
+			chmod 755 $NINJA_FOLDER/ninja
+		fi
+		export PATH=$NINJA_FOLDER:$PATH
+	else
+		if [ "$(dpkg-query -W -f '${db:Status-Status}\n' ninja 2>/dev/null)" != "installed" ]; then
+			echo "Package 'ninja' is not installed."
+			echo "You can install it with"
+			echo
+			echo "  pkg install ninja"
+			echo
+			echo "or build it from source with"
+			echo
+			echo "  ./build-package.sh ninja"
+			echo
+			exit 1
+		fi
 	fi
-	export PATH=$NINJA_FOLDER:$PATH
 }
diff --git a/scripts/build/setup/termux_setup_protobuf.sh b/scripts/build/setup/termux_setup_protobuf.sh
index 26efaec6e..0cdf0665c 100644
--- a/scripts/build/setup/termux_setup_protobuf.sh
+++ b/scripts/build/setup/termux_setup_protobuf.sh
@@ -3,17 +3,32 @@ termux_setup_protobuf() {
 	local _PROTOBUF_ZIP=protoc-$_PROTOBUF_VERSION-linux-x86_64.zip
 	local _PROTOBUF_FOLDER=$TERMUX_COMMON_CACHEDIR/protobuf-$_PROTOBUF_VERSION
 
-	if [ ! -d "$_PROTOBUF_FOLDER" ]; then
-		termux_download \
+	if [ -z "$TERMUX_ON_DEVICE_BUILD" ]; then
+		if [ ! -d "$_PROTOBUF_FOLDER" ]; then
+			termux_download \
 				https://github.com/protocolbuffers/protobuf/releases/download/v$_PROTOBUF_VERSION/$_PROTOBUF_ZIP \
 				$TERMUX_PKG_TMPDIR/$_PROTOBUF_ZIP \
 				15e395b648a1a6dda8fd66868824a396e9d3e89bc2c8648e3b9ab9801bea5d55
 
-		rm -Rf "$TERMUX_PKG_TMPDIR/protoc-$_PROTOBUF_VERSION-linux-x86_64"
-		unzip $TERMUX_PKG_TMPDIR/$_PROTOBUF_ZIP -d $TERMUX_PKG_TMPDIR/protobuf-$_PROTOBUF_VERSION
-		mv "$TERMUX_PKG_TMPDIR/protobuf-$_PROTOBUF_VERSION" \
-			$_PROTOBUF_FOLDER
-	fi
+			rm -Rf "$TERMUX_PKG_TMPDIR/protoc-$_PROTOBUF_VERSION-linux-x86_64"
+			unzip $TERMUX_PKG_TMPDIR/$_PROTOBUF_ZIP -d $TERMUX_PKG_TMPDIR/protobuf-$_PROTOBUF_VERSION
+			mv "$TERMUX_PKG_TMPDIR/protobuf-$_PROTOBUF_VERSION" \
+				$_PROTOBUF_FOLDER
+		fi
 
-	export PATH=$_PROTOBUF_FOLDER/bin/:$PATH
+		export PATH=$_PROTOBUF_FOLDER/bin/:$PATH
+	else
+		if [ "$(dpkg-query -W -f '${db:Status-Status}\n' protobuf 2>/dev/null)" != "installed" ]; then
+			echo "Package 'protobuf' is not installed."
+			echo "You can install it with"
+			echo
+			echo "  pkg install protobuf"
+			echo
+			echo "or build it from source with"
+			echo
+			echo "  ./build-package.sh libprotobuf"
+			echo
+			exit 1
+		fi
+	fi
 }
diff --git a/scripts/build/setup/termux_setup_rust.sh b/scripts/build/setup/termux_setup_rust.sh
index 89aedb65e..aee7755a0 100644
--- a/scripts/build/setup/termux_setup_rust.sh
+++ b/scripts/build/setup/termux_setup_rust.sh
@@ -5,6 +5,25 @@ termux_setup_rust() {
 		CARGO_TARGET_NAME=$TERMUX_ARCH-linux-android
 	fi
 
+	export RUSTFLAGS="-C link-arg=-Wl,-rpath=$TERMUX_PREFIX/lib -C link-arg=-Wl,--enable-new-dtags"
+
+	if [ -n "$TERMUX_ON_DEVICE_BUILD" ]; then
+		if [ "$(dpkg-query -W -f '${db:Status-Status}\n' rust 2>/dev/null)" != "installed" ]; then
+			echo "Package 'rust' is not installed."
+			echo "You can install it with"
+			echo
+			echo "  pkg install rust"
+			echo
+			echo "or build it from source with"
+			echo
+			echo "  ./build-package.sh rust"
+			echo
+			echo "Note that package 'rust' is known to be problematic for building on device."
+			exit 1
+		fi
+		return
+	fi
+
 	local ENV_NAME=CARGO_TARGET_${CARGO_TARGET_NAME^^}_LINKER
 	ENV_NAME=${ENV_NAME//-/_}
 	export $ENV_NAME=$CC
diff --git a/scripts/build/termux_download_deb.sh b/scripts/build/termux_download_deb.sh
index 5b4351b81..e34a9b42b 100755
--- a/scripts/build/termux_download_deb.sh
+++ b/scripts/build/termux_download_deb.sh
@@ -2,8 +2,15 @@ termux_download_deb() {
 	local PACKAGE=$1
 	local PACKAGE_ARCH=$2
 	local VERSION=$3
+
+	if [ -n "$TERMUX_ON_DEVICE_BUILD" ]; then
+		apt install -y "${PACKAGE}=${VERSION}"
+		return "$?"
+	fi
+
 	local DEB_FILE=${PACKAGE}_${VERSION}_${PACKAGE_ARCH}.deb
 	PKG_HASH=""
+
 	for idx in $(seq ${#TERMUX_REPO_URL[@]}); do
 		local TERMUX_REPO_NAME=$(echo ${TERMUX_REPO_URL[$idx-1]} | sed -e 's%https://%%g' -e 's%http://%%g' -e 's%/%-%g')
 		local PACKAGE_FILE_PATH="${TERMUX_REPO_NAME}-${TERMUX_REPO_DISTRIBUTION[$idx-1]}-${TERMUX_REPO_COMPONENT[$idx-1]}-Packages"
@@ -17,6 +24,7 @@ termux_download_deb() {
 			fi
 		fi
 	done
+
 	if [ "$PKG_HASH" = "" ]; then
 		return 1
 	else
diff --git a/scripts/build/termux_get_repo_files.sh b/scripts/build/termux_get_repo_files.sh
index 8f79d5976..9deb8b853 100644
--- a/scripts/build/termux_get_repo_files.sh
+++ b/scripts/build/termux_get_repo_files.sh
@@ -1,4 +1,7 @@
 termux_get_repo_files() {
+	# Not needed for on-device builds.
+	[ -n "$TERMUX_ON_DEVICE_BUILD" ] && return
+
 	# Ensure folders present (but not $TERMUX_PKG_SRCDIR, it will be created in build)
 	mkdir -p "$TERMUX_COMMON_CACHEDIR" \
 		 "$TERMUX_COMMON_CACHEDIR-$TERMUX_ARCH" \
@@ -10,11 +13,12 @@ termux_get_repo_files() {
 		 "$TERMUX_PKG_CACHEDIR" \
 		 "$TERMUX_PKG_MASSAGEDIR" \
 		 $TERMUX_PREFIX/{bin,etc,lib,libexec,share,tmp,include}
+
 	if [ "$TERMUX_INSTALL_DEPS" = true ]; then
 		if [ "$TERMUX_NO_CLEAN" = false ]; then
 			# Remove all previously extracted/built files from $TERMUX_PREFIX:
 			rm -rf $TERMUX_PREFIX
-			rm -f /data/data/.built-packages/*
+			rm -f $TERMUX_BUILT_PACKAGES_DIRECTORY/*
 		fi
 
 		for idx in $(seq ${#TERMUX_REPO_URL[@]}); do
diff --git a/scripts/build/termux_step_finish_build.sh b/scripts/build/termux_step_finish_build.sh
index b8528b897..4186fa44d 100644
--- a/scripts/build/termux_step_finish_build.sh
+++ b/scripts/build/termux_step_finish_build.sh
@@ -1,7 +1,9 @@
 termux_step_finish_build() {
 	echo "termux - build of '$TERMUX_PKG_NAME' done"
 	test -t 1 && printf "\033]0;%s - DONE\007" "$TERMUX_PKG_NAME"
-	mkdir -p /data/data/.built-packages
-	echo "$TERMUX_PKG_FULLVERSION" > "/data/data/.built-packages/$TERMUX_PKG_NAME"
+
+	mkdir -p "$TERMUX_BUILT_PACKAGES_DIRECTORY"
+	echo "$TERMUX_PKG_FULLVERSION" > "$TERMUX_BUILT_PACKAGES_DIRECTORY/$TERMUX_PKG_NAME"
+
 	exit 0
 }
diff --git a/scripts/build/termux_step_handle_buildarch.sh b/scripts/build/termux_step_handle_buildarch.sh
index bd5ab2c3d..43b89e843 100644
--- a/scripts/build/termux_step_handle_buildarch.sh
+++ b/scripts/build/termux_step_handle_buildarch.sh
@@ -1,4 +1,6 @@
 termux_step_handle_buildarch() {
+	[ -n "$TERMUX_ON_DEVICE_BUILD" ] && return
+
 	# If $TERMUX_PREFIX already exists, it may have been built for a different arch
 	local TERMUX_ARCH_FILE=/data/TERMUX_ARCH
 	if [ -f "${TERMUX_ARCH_FILE}" ]; then
diff --git a/scripts/build/termux_step_massage.sh b/scripts/build/termux_step_massage.sh
index 154206a20..4358f94f9 100644
--- a/scripts/build/termux_step_massage.sh
+++ b/scripts/build/termux_step_massage.sh
@@ -4,37 +4,34 @@ termux_step_massage() {
 	# Remove lib/charset.alias which is installed by gettext-using packages:
 	rm -f lib/charset.alias
 
-	# Remove non-english man pages:
-	test -d share/man && (cd share/man; for f in $(ls | grep -v man); do rm -Rf $f; done )
-
 	# Remove locale files we're not interested in::
 	rm -Rf share/locale
 
 	# Remove old kept libraries (readline):
-	find . -name '*.old' -delete
+	find . -name '*.old' -print0 | xargs -0 -r rm -f
 
 	# Move over sbin to bin:
 	for file in sbin/*; do if test -f "$file"; then mv "$file" bin/; fi; done
 
-	# Remove world permissions and add write permissions.
-	# The -f flag is used to suppress warnings about dangling symlinks (such
-	# as ones to /system/... which may not exist on the build machine):
-	find . -exec chmod -f u+w,g-rwx,o-rwx \{\} \;
+	# Remove world permissions and make sure that user still have read-write permissions.
+	chmod -Rf u+rw,g-rwx,o-rwx . || true
 
 	if [ "$TERMUX_DEBUG" = "" ]; then
 		# Strip binaries. file(1) may fail for certain unusual files, so disable pipefail.
 		set +e +o pipefail
-		find . -type f | xargs -r file | grep -E "(executable|shared object)" | grep ELF | cut -f 1 -d : | \
+		find bin lib libexec -type f | xargs -r file | grep -E "ELF .+ (executable|shared object)" | cut -f 1 -d : | \
 			xargs -r "$STRIP" --strip-unneeded --preserve-dates
 		set -e -o pipefail
 	fi
-	# Remove DT_ entries which the android 5.1 linker warns about:
-	find . -type f -print0 | xargs -r -0 "$TERMUX_ELF_CLEANER"
+
+	# Remove entries unsupported by Android's linker:
+	find bin lib libexec -type f -print0 | xargs -r -0 "$TERMUX_ELF_CLEANER"
 
 	# Fix shebang paths:
 	while IFS= read -r -d '' file
 	do
-		head -c 100 "$file" | grep -E "^#\!.*\\/bin\\/.*" | grep -q -E -v "^#\! ?\\/system" && sed --follow-symlinks -i -E "1 s@^#\!(.*)/bin/(.*)@#\!$TERMUX_PREFIX/bin/\2@" "$file"
+		head -c 100 "$file" | grep -E "^#\!.*\\/bin\\/.*" | grep -q -E -v "^#\! ?\\/system" && \
+			sed --follow-symlinks -i -E "1 s@^#\!(.*)/bin/(.*)@#\!$TERMUX_PREFIX/bin/\2@" "$file"
 	done < <(find -L . -type f -print0)
 
 	test ! -z "$TERMUX_PKG_RM_AFTER_INSTALL" && rm -Rf $TERMUX_PKG_RM_AFTER_INSTALL
@@ -42,6 +39,9 @@ termux_step_massage() {
 	find . -type d -empty -delete # Remove empty directories
 
 	if [ -d share/man ]; then
+		# Remove non-english man pages:
+		find share/man -mindepth 1 -maxdepth 1 -type d ! -name man\* | xargs -r rm -rf
+
 		# Compress man pages with gzip:
 		find share/man -type f ! -iname \*.gz -print0 | xargs -r -0 gzip
 
@@ -59,6 +59,4 @@ termux_step_massage() {
 
 	# .. remove empty directories (NOTE: keep this last):
 	find . -type d -empty -delete
-	# Make sure user can read and write all files (problem with dpkg otherwise):
-	chmod -R u+rw .
 }
diff --git a/scripts/build/termux_step_setup_toolchain.sh b/scripts/build/termux_step_setup_toolchain.sh
index 1b4429983..0fe6d322a 100644
--- a/scripts/build/termux_step_setup_toolchain.sh
+++ b/scripts/build/termux_step_setup_toolchain.sh
@@ -1,32 +1,32 @@
 termux_step_setup_toolchain() {
-	export PATH=$TERMUX_STANDALONE_TOOLCHAIN/bin:$PATH
-
 	export CFLAGS=""
 	export LDFLAGS="-L${TERMUX_PREFIX}/lib"
 
-	export AS=${TERMUX_HOST_PLATFORM}-clang
+	export AS=$TERMUX_HOST_PLATFORM-clang
 	export CC=$TERMUX_HOST_PLATFORM-clang
 	export CXX=$TERMUX_HOST_PLATFORM-clang++
-
-	export CCTERMUX_HOST_PLATFORM=$TERMUX_HOST_PLATFORM$TERMUX_PKG_API_LEVEL
-	if [ $TERMUX_ARCH = arm ]; then
-	       CCTERMUX_HOST_PLATFORM=armv7a-linux-androideabi$TERMUX_PKG_API_LEVEL
-	fi
 	export AR=$TERMUX_HOST_PLATFORM-ar
-	export CPP=${TERMUX_HOST_PLATFORM}-cpp
-	export CC_FOR_BUILD=gcc
+	export CPP=$TERMUX_HOST_PLATFORM-cpp
 	export LD=$TERMUX_HOST_PLATFORM-ld
 	export OBJCOPY=$TERMUX_HOST_PLATFORM-objcopy
 	export OBJDUMP=$TERMUX_HOST_PLATFORM-objdump
-	# Setup pkg-config for cross-compiling:
-	export PKG_CONFIG=$TERMUX_STANDALONE_TOOLCHAIN/bin/${TERMUX_HOST_PLATFORM}-pkg-config
 	export RANLIB=$TERMUX_HOST_PLATFORM-ranlib
 	export READELF=$TERMUX_HOST_PLATFORM-readelf
 	export STRIP=$TERMUX_HOST_PLATFORM-strip
 
-	# Android 7 started to support DT_RUNPATH (but not DT_RPATH), so we may want
-	# LDFLAGS+="-Wl,-rpath=$TERMUX_PREFIX/lib -Wl,--enable-new-dtags"
-	# and no longer remove DT_RUNPATH in termux-elf-cleaner.
+	if [ -z "$TERMUX_ON_DEVICE_BUILD" ]; then
+		export PATH=$TERMUX_STANDALONE_TOOLCHAIN/bin:$PATH
+		export CC_FOR_BUILD=gcc
+		export PKG_CONFIG=$TERMUX_STANDALONE_TOOLCHAIN/bin/${TERMUX_HOST_PLATFORM}-pkg-config
+		export CCTERMUX_HOST_PLATFORM=$TERMUX_HOST_PLATFORM$TERMUX_PKG_API_LEVEL
+		if [ $TERMUX_ARCH = arm ]; then
+			CCTERMUX_HOST_PLATFORM=armv7a-linux-androideabi$TERMUX_PKG_API_LEVEL
+		fi
+	else
+		# Some build scripts use environment variable 'PKG_CONFIG', so
+		# using this for on-device builds too.
+		export PKG_CONFIG=pkg-config
+	fi
 
 	if [ "$TERMUX_ARCH" = "arm" ]; then
 		# https://developer.android.com/ndk/guides/standalone_toolchain.html#abi_compatibility:
@@ -51,6 +51,10 @@ termux_step_setup_toolchain() {
 		CFLAGS+=" -Oz"
 	fi
 
+	# Android 7 started to support DT_RUNPATH (but not DT_RPATH), so we may want
+	# LDFLAGS+="-Wl,-rpath=$TERMUX_PREFIX/lib -Wl,--enable-new-dtags"
+	# and no longer remove DT_RUNPATH in termux-elf-cleaner.
+
 	# Basic hardening.
 	CFLAGS+=" -fstack-protector-strong"
 	LDFLAGS+=" -Wl,-z,relro,-z,now"
@@ -69,7 +73,7 @@ termux_step_setup_toolchain() {
 	export ac_cv_func_sigsetmask=no
 	export ac_cv_c_bigendian=no
 
-	if [ ! -d $TERMUX_STANDALONE_TOOLCHAIN ]; then
+	if [ -z "$TERMUX_ON_DEVICE_BUILD" ] && [ ! -d $TERMUX_STANDALONE_TOOLCHAIN ]; then
 		# Do not put toolchain in place until we are done with setup, to avoid having a half setup
 		# toolchain left in place if something goes wrong (or process is just aborted):
 		local _TERMUX_TOOLCHAIN_TMPDIR=${TERMUX_STANDALONE_TOOLCHAIN}-tmp
@@ -158,16 +162,19 @@ termux_step_setup_toolchain() {
 	fi
 
 	export PKG_CONFIG_LIBDIR="$TERMUX_PKG_CONFIG_LIBDIR"
-	# Create a pkg-config wrapper. We use path to host pkg-config to
-	# avoid picking up a cross-compiled pkg-config later on.
-	local _HOST_PKGCONFIG
-	_HOST_PKGCONFIG=$(which pkg-config)
-	mkdir -p $TERMUX_STANDALONE_TOOLCHAIN/bin "$PKG_CONFIG_LIBDIR"
-	cat > "$PKG_CONFIG" <<-HERE
-		#!/bin/sh
-		export PKG_CONFIG_DIR=
-		export PKG_CONFIG_LIBDIR=$PKG_CONFIG_LIBDIR
-		exec $_HOST_PKGCONFIG "\$@"
-	HERE
-	chmod +x "$PKG_CONFIG"
+
+	if [ -z "$TERMUX_ON_DEVICE_BUILD" ]; then
+		# Create a pkg-config wrapper. We use path to host pkg-config to
+		# avoid picking up a cross-compiled pkg-config later on.
+		local _HOST_PKGCONFIG
+		_HOST_PKGCONFIG=$(which pkg-config)
+		mkdir -p $TERMUX_STANDALONE_TOOLCHAIN/bin "$PKG_CONFIG_LIBDIR"
+		cat > "$PKG_CONFIG" <<-HERE
+			#!/bin/sh
+			export PKG_CONFIG_DIR=
+			export PKG_CONFIG_LIBDIR=$PKG_CONFIG_LIBDIR
+			exec $_HOST_PKGCONFIG "\$@"
+		HERE
+		chmod +x "$PKG_CONFIG"
+	fi
 }
diff --git a/scripts/build/termux_step_setup_variables.sh b/scripts/build/termux_step_setup_variables.sh
index f3696babc..4c9c73195 100644
--- a/scripts/build/termux_step_setup_variables.sh
+++ b/scripts/build/termux_step_setup_variables.sh
@@ -16,6 +16,14 @@ termux_step_setup_variables() {
 	: "${TERMUX_PKG_MAINTAINER:="Fredrik Fornwall @fornwall"}"
 	: "${TERMUX_PACKAGES_DIRECTORIES:="packages"}"
 
+	if [ -n "$TERMUX_ON_DEVICE_BUILD" ]; then
+		# For on-device builds cross-compiling is not supported so we can
+		# store information about built packages under $TERMUX_TOPDIR.
+		TERMUX_BUILT_PACKAGES_DIRECTORY="$TERMUX_TOPDIR/.built-packages"
+	else
+		TERMUX_BUILT_PACKAGES_DIRECTORY="/data/data/.built-packages"
+	fi
+
 	TERMUX_REPO_URL=(
 		https://termux.net
 		https://dl.bintray.com/grimler/game-packages-21
@@ -52,10 +60,11 @@ termux_step_setup_variables() {
 	TERMUX_HOST_PLATFORM="${TERMUX_ARCH}-linux-android"
 	if [ "$TERMUX_ARCH" = "arm" ]; then TERMUX_HOST_PLATFORM="${TERMUX_HOST_PLATFORM}eabi"; fi
 
-	if [ ! -d "$NDK" ]; then
+	if [ -z "$TERMUX_ON_DEVICE_BUILD" ] && [ ! -d "$NDK" ]; then
 		termux_error_exit 'NDK not pointing at a directory!'
 	fi
-	if ! grep -s -q "Pkg.Revision = $TERMUX_NDK_VERSION_NUM" "$NDK/source.properties"; then
+
+	if [ -z "$TERMUX_ON_DEVICE_BUILD" ] && ! grep -s -q "Pkg.Revision = $TERMUX_NDK_VERSION_NUM" "$NDK/source.properties"; then
 		termux_error_exit "Wrong NDK version - we need $TERMUX_NDK_VERSION"
 	fi
 
@@ -95,7 +104,7 @@ termux_step_setup_variables() {
 	TERMUX_PKG_BUILD_DEPENDS=""
 	TERMUX_PKG_HOMEPAGE=""
 	TERMUX_PKG_DESCRIPTION="FIXME:Add description"
-	TERMUX_PKG_LICENSE_FILE="" # Relative path from $TERMUX_PKG_SRCDIR to LICENSE file. It is installed to $PREFIX/share/$TERMUX_PKG_NAME.
+	TERMUX_PKG_LICENSE_FILE="" # Relative path from $TERMUX_PKG_SRCDIR to LICENSE file. It is installed to $TERMUX_PREFIX/share/$TERMUX_PKG_NAME.
 	TERMUX_PKG_ESSENTIAL=""
 	TERMUX_PKG_CONFLICTS="" # https://www.debian.org/doc/debian-policy/ch-relationships.html#s-conflicts
 	TERMUX_PKG_RECOMMENDS="" # https://www.debian.org/doc/debian-policy/ch-relationships.html#s-binarydeps
diff --git a/scripts/build/termux_step_start_build.sh b/scripts/build/termux_step_start_build.sh
index 64d382caf..bbbc5f3ad 100644
--- a/scripts/build/termux_step_start_build.sh
+++ b/scripts/build/termux_step_start_build.sh
@@ -30,11 +30,14 @@ termux_step_start_build() {
 		DEBUG=""
 	fi
 
-	if [ -z "$TERMUX_DEBUG" ] &&
-	   [ -z "${TERMUX_FORCE_BUILD+x}" ] &&
-	   [ -e "/data/data/.built-packages/$TERMUX_PKG_NAME" ]; then
-		if [ "$(cat "/data/data/.built-packages/$TERMUX_PKG_NAME")" = "$TERMUX_PKG_FULLVERSION" ]; then
-			echo "$TERMUX_PKG_NAME@$TERMUX_PKG_FULLVERSION built - skipping (rm /data/data/.built-packages/$TERMUX_PKG_NAME to force rebuild)"
+	if [ -z "$TERMUX_DEBUG" ] && [ -z "${TERMUX_FORCE_BUILD+x}" ]; then
+		if [ -e "$TERMUX_BUILT_PACKAGES_DIRECTORY/$TERMUX_PKG_NAME" ] &&
+		   [ "$(cat "$TERMUX_BUILT_PACKAGES_DIRECTORY/$TERMUX_PKG_NAME")" = "$TERMUX_PKG_FULLVERSION" ]; then
+			echo "$TERMUX_PKG_NAME@$TERMUX_PKG_FULLVERSION built - skipping (rm $TERMUX_BUILT_PACKAGES_DIRECTORY/$TERMUX_PKG_NAME to force rebuild)"
+			exit 0
+		elif [ -n "$TERMUX_ON_DEVICE_BUILD" ] &&
+		     [ "$(dpkg-query -W -f '${db:Status-Status} ${Version}\n' "$TERMUX_PKG_NAME" 2>/dev/null)" = "installed $TERMUX_PKG_FULLVERSION" ]; then
+			echo "$TERMUX_PKG_NAME@$TERMUX_PKG_FULLVERSION installed - skipping"
 			exit 0
 		fi
 	fi
@@ -42,6 +45,10 @@ termux_step_start_build() {
 	if [ "$TERMUX_SKIP_DEPCHECK" = false ] && [ "$TERMUX_INSTALL_DEPS" = true ]; then
 		# Download repo files
 		termux_get_repo_files
+
+		# When doing build on device, ensure that apt lists are up-to-date.
+		[ -n "$TERMUX_ON_DEVICE_BUILD" ] && apt update
+
 		# Download dependencies
 		while read PKG PKG_DIR; do
 			if [ -z $PKG ]; then
@@ -57,27 +64,29 @@ termux_step_start_build() {
 				echo "Downloading dependency $PKG@$DEP_VERSION if necessary..."
 			fi
 
-			if [ -e "/data/data/.built-packages/$PKG" ]; then
-				if [ "$(cat "/data/data/.built-packages/$PKG")" = "$DEP_VERSION" ]; then
+			if [ -e "$TERMUX_BUILT_PACKAGES_DIRECTORY/$PKG" ]; then
+				if [ "$(cat "$TERMUX_BUILT_PACKAGES_DIRECTORY/$PKG")" = "$DEP_VERSION" ]; then
 					continue
 				fi
 			fi
 
 			if ! termux_download_deb $PKG $DEP_ARCH $DEP_VERSION; then
 				echo "Download of $PKG@$DEP_VERSION from $TERMUX_REPO_URL failed, building instead"
-				TERMUX_BUILD_IGNORE_LOCK=true ./build-package.sh -a $TERMUX_ARCH -I "${PKG_DIR}"
+				TERMUX_BUILD_IGNORE_LOCK=true ./build-package.sh -I "${PKG_DIR}"
 				continue
 			else
-				if [ ! "$TERMUX_QUIET_BUILD" = true ]; then echo "extracting $PKG..."; fi
-				(
-					cd $TERMUX_COMMON_CACHEDIR-$DEP_ARCH
-					ar x ${PKG}_${DEP_VERSION}_${DEP_ARCH}.deb data.tar.xz
-					tar -xf data.tar.xz --no-overwrite-dir -C /
-				)
+				if [ -z "$TERMUX_ON_DEVICE_BUILD" ]; then
+					if [ ! "$TERMUX_QUIET_BUILD" = true ]; then echo "extracting $PKG..."; fi
+					(
+						cd $TERMUX_COMMON_CACHEDIR-$DEP_ARCH
+						ar x ${PKG}_${DEP_VERSION}_${DEP_ARCH}.deb data.tar.xz
+						tar -xf data.tar.xz --no-overwrite-dir -C /
+					)
+				fi
 			fi
 
-			mkdir -p /data/data/.built-packages
-			echo "$DEP_VERSION" > "/data/data/.built-packages/$PKG"
+			mkdir -p $TERMUX_BUILT_PACKAGES_DIRECTORY
+			echo "$DEP_VERSION" > "$TERMUX_BUILT_PACKAGES_DIRECTORY/$PKG"
 		done<<<$(./scripts/buildorder.py -i "$TERMUX_PKG_BUILDER_DIR" $TERMUX_PACKAGES_DIRECTORIES || echo "ERROR")
 	elif [ "$TERMUX_SKIP_DEPCHECK" = false ] && [ "$TERMUX_INSTALL_DEPS" = false ]; then
 		# Build dependencies
@@ -89,12 +98,12 @@ termux_step_start_build() {
 			fi
 			echo "Building dependency $PKG if necessary..."
 			# Built dependencies are put in the default TERMUX_DEBDIR instead of the specified one
-			TERMUX_BUILD_IGNORE_LOCK=true ./build-package.sh -a $TERMUX_ARCH -s "${PKG_DIR}"
+			TERMUX_BUILD_IGNORE_LOCK=true ./build-package.sh -s "${PKG_DIR}"
 		done<<<$(./scripts/buildorder.py "$TERMUX_PKG_BUILDER_DIR" $TERMUX_PACKAGES_DIRECTORIES || echo "ERROR")
 	fi
 
-	# Following directories may contain objects with RO-only permissions which
-	# makes them undeletable. We need fix that.
+	# Following directories may contain files with read-only permissions which
+	# makes them undeletable. We need to fix that.
 	[ -d "$TERMUX_PKG_BUILDDIR" ] && chmod +w -R "$TERMUX_PKG_BUILDDIR"
 	[ -d "$TERMUX_PKG_SRCDIR" ] && chmod +w -R "$TERMUX_PKG_SRCDIR"
 
@@ -117,7 +126,7 @@ termux_step_start_build() {
 
 	# Make $TERMUX_PREFIX/bin/sh executable on the builder, so that build
 	# scripts can assume that it works on both builder and host later on:
-	ln -f -s /bin/sh "$TERMUX_PREFIX/bin/sh"
+	[ -z "$TERMUX_ON_DEVICE_BUILD" ] && ln -sf /bin/sh "$TERMUX_PREFIX/bin/sh"
 
 	local TERMUX_ELF_CLEANER_SRC=$TERMUX_COMMON_CACHEDIR/termux-elf-cleaner.cpp
 	local TERMUX_ELF_CLEANER_VERSION
diff --git a/scripts/buildorder.py b/scripts/buildorder.py
index 238483302..0a7b4224b 100755
--- a/scripts/buildorder.py
+++ b/scripts/buildorder.py
@@ -62,10 +62,12 @@ class TermuxPackage(object):
             raise Exception("build.sh not found for package '" + self.name + "'")
 
         self.deps = parse_build_file_dependencies(build_sh_path)
-        always_deps = ['libc++']
-        for dependency_name in always_deps:
-            if dependency_name not in self.deps and self.name not in always_deps:
-                self.deps.add(dependency_name)
+
+        if os.getenv('TERMUX_ON_DEVICE_BUILD') is None:
+            always_deps = ['libc++']
+            for dependency_name in always_deps:
+                if dependency_name not in self.deps and self.name not in always_deps:
+                    self.deps.add(dependency_name)
 
         # search subpackages
         self.subpkgs = []
diff --git a/scripts/setup-termux.sh b/scripts/setup-termux.sh
new file mode 100755
index 000000000..cabd6df57
--- /dev/null
+++ b/scripts/setup-termux.sh
@@ -0,0 +1,45 @@
+#!/data/data/com.termux/files/usr/bin/sh
+
+PACKAGES="autoconf"
+PACKAGES+=" automake"
+PACKAGES+=" bc"
+PACKAGES+=" bison"
+PACKAGES+=" bzip2"
+PACKAGES+=" clang"
+PACKAGES+=" cmake"
+PACKAGES+=" coreutils"
+PACKAGES+=" curl"
+PACKAGES+=" diffutils"
+PACKAGES+=" ed"
+PACKAGES+=" file"
+PACKAGES+=" findutils"
+PACKAGES+=" flex"
+PACKAGES+=" gawk"
+PACKAGES+=" gettext"
+PACKAGES+=" git"
+PACKAGES+=" golang"
+PACKAGES+=" gperf"
+PACKAGES+=" grep"
+PACKAGES+=" gzip"
+PACKAGES+=" libtool"
+PACKAGES+=" lzip"
+PACKAGES+=" lzop"
+PACKAGES+=" m4"
+PACKAGES+=" make"
+PACKAGES+=" ninja"
+PACKAGES+=" patch"
+PACKAGES+=" perl"
+PACKAGES+=" pkg-config"
+PACKAGES+=" protobuf"
+PACKAGES+=" python"
+PACKAGES+=" python2"
+PACKAGES+=" rust"
+PACKAGES+=" sed"
+PACKAGES+=" tar"
+PACKAGES+=" texinfo"
+PACKAGES+=" unzip"
+PACKAGES+=" xz-utils"
+
+apt update
+apt dist-upgrade -y
+apt install -y $PACKAGES