diff --git a/cargo.sh b/cargo.sh
index 16e49b20423..b68a08ee88f 100755
--- a/cargo.sh
+++ b/cargo.sh
@@ -12,7 +12,7 @@ TOOLCHAIN=$(cat rust-toolchain | grep channel | sed 's/channel = "\(.*\)"/\1/')
 
 popd >/dev/null
 
-if [[ $(rustc -V) != $(rustc +${TOOLCHAIN} -V) ]]; then
+if [[ $(${RUSTC} -V) != $(${RUSTC} +${TOOLCHAIN} -V) ]]; then
     echo "rustc_codegen_gcc is build for $(rustc +${TOOLCHAIN} -V) but the default rustc version is $(rustc -V)."
     echo "Using $(rustc +${TOOLCHAIN} -V)."
 fi
diff --git a/config.sh b/config.sh
index 99ee9b054c6..006758e19e1 100644
--- a/config.sh
+++ b/config.sh
@@ -4,19 +4,25 @@ export CARGO_INCREMENTAL=0
 
 if [ -f ./gcc_path ]; then
     export GCC_PATH=$(cat gcc_path)
+elif (( $use_system_gcc == 1 )); then
+    echo 'Using system GCC'
 else
     echo 'Please put the path to your custom build of libgccjit in the file `gcc_path`, see Readme.md for details'
     exit 1
 fi
 
+if [[ -z "$RUSTC" ]]; then
+    export RUSTC="rustc"
+fi
+
 unamestr=`uname`
 if [[ "$unamestr" == 'Linux' ]]; then
-   dylib_ext='so'
+    dylib_ext='so'
 elif [[ "$unamestr" == 'Darwin' ]]; then
-   dylib_ext='dylib'
+    dylib_ext='dylib'
 else
-   echo "Unsupported os"
-   exit 1
+    echo "Unsupported os"
+    exit 1
 fi
 
 HOST_TRIPLE=$(rustc -vV | grep host | cut -d: -f2 | tr -d " ")
@@ -44,17 +50,30 @@ if [[ ! -v FAT_LTO ]]; then
     disable_lto_flags='-Clto=off'
 fi
 
-export RUSTFLAGS="$CG_RUSTFLAGS $linker -Csymbol-mangling-version=v0 -Cdebuginfo=2 $disable_lto_flags -Zcodegen-backend=$(pwd)/target/${CHANNEL:-debug}/librustc_codegen_gcc.$dylib_ext --sysroot $(pwd)/build_sysroot/sysroot $TEST_FLAGS"
+if [[ -z "$BUILTIN_BACKEND" ]]; then
+    export RUSTFLAGS="$CG_RUSTFLAGS $linker -Csymbol-mangling-version=v0 -Cdebuginfo=2 $disable_lto_flags -Zcodegen-backend=$(pwd)/target/${CHANNEL:-debug}/librustc_codegen_gcc.$dylib_ext --sysroot $(pwd)/build_sysroot/sysroot $TEST_FLAGS"
+else
+    export RUSTFLAGS="$CG_RUSTFLAGS $linker -Csymbol-mangling-version=v0 -Cdebuginfo=2 $disable_lto_flags -Zcodegen-backend=gcc $TEST_FLAGS -Cpanic=abort"
+fi
 
 # FIXME(antoyo): remove once the atomic shim is gone
 if [[ unamestr == 'Darwin' ]]; then
-   export RUSTFLAGS="$RUSTFLAGS -Clink-arg=-undefined -Clink-arg=dynamic_lookup"
+    export RUSTFLAGS="$RUSTFLAGS -Clink-arg=-undefined -Clink-arg=dynamic_lookup"
 fi
 
-RUSTC="rustc $RUSTFLAGS -L crate=target/out --out-dir target/out"
+if [[ -z "$cargo_target_dir" ]]; then
+    RUST_CMD="$RUSTC $RUSTFLAGS -L crate=target/out --out-dir target/out"
+    cargo_target_dir="target/out"
+else
+    RUST_CMD="$RUSTC $RUSTFLAGS -L crate=$cargo_target_dir --out-dir $cargo_target_dir"
+fi
 export RUSTC_LOG=warn # display metadata load errors
 
-export LD_LIBRARY_PATH="$(pwd)/target/out:$(pwd)/build_sysroot/sysroot/lib/rustlib/$TARGET_TRIPLE/lib:$GCC_PATH"
+export LD_LIBRARY_PATH="$(pwd)/target/out:$(pwd)/build_sysroot/sysroot/lib/rustlib/$TARGET_TRIPLE/lib"
+if [[ ! -z "$:$GCC_PATH" ]]; then
+    export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$GCC_PATH"
+fi
+
 export DYLD_LIBRARY_PATH=$LD_LIBRARY_PATH
 # NOTE: To avoid the -fno-inline errors, use /opt/gcc/bin/gcc instead of cc.
 # To do so, add a symlink for cc to /opt/gcc/bin/gcc in our PATH.
diff --git a/test.sh b/test.sh
index fa34c31dbaa..e896237a1ea 100755
--- a/test.sh
+++ b/test.sh
@@ -5,16 +5,6 @@
 set -e
 #set -x
 
-if [ -f ./gcc_path ]; then
-    export GCC_PATH=$(cat gcc_path)
-else
-    echo 'Please put the path to your custom build of libgccjit in the file `gcc_path`, see Readme.md for details'
-    exit 1
-fi
-
-export LD_LIBRARY_PATH="$GCC_PATH"
-export LIBRARY_PATH="$GCC_PATH"
-
 flags=
 gcc_master_branch=1
 channel="debug"
@@ -22,12 +12,18 @@ funcs=()
 build_only=0
 nb_parts=0
 current_part=0
+use_system_gcc=0
+use_backend=0
+cargo_target_dir=""
+
+export CHANNEL='debug'
 
 while [[ $# -gt 0 ]]; do
     case $1 in
         --release)
             codegen_channel=release
             channel="release"
+            export CHANNEL='release'
             shift
             ;;
         --release-sysroot)
@@ -111,6 +107,22 @@ while [[ $# -gt 0 ]]; do
             build_only=1
             shift
             ;;
+        "--use-system-gcc")
+            use_system_gcc=1
+            shift
+            ;;
+        "--use-backend")
+            use_backend=1
+            shift
+            export BUILTIN_BACKEND=$1
+            shift
+            ;;
+        "--out-dir")
+            shift
+            export CARGO_TARGET_DIR=$1
+            cargo_target_dir=$1
+            shift
+            ;;
         "--nb-parts")
             shift
             nb_parts=$1
@@ -128,13 +140,25 @@ while [[ $# -gt 0 ]]; do
     esac
 done
 
-if [[ $channel == "release" ]]; then
-    export CHANNEL='release'
-    CARGO_INCREMENTAL=1 cargo rustc --release $flags
+if [ -f ./gcc_path ]; then
+    export GCC_PATH=$(cat gcc_path)
+elif (( $use_system_gcc == 1 )); then
+    echo 'Using system GCC'
 else
-    echo $LD_LIBRARY_PATH
-    export CHANNEL='debug'
-    cargo rustc $flags
+    echo 'Please put the path to your custom build of libgccjit in the file `gcc_path`, see Readme.md for details'
+    exit 1
+fi
+
+export LD_LIBRARY_PATH="$GCC_PATH"
+export LIBRARY_PATH="$GCC_PATH"
+
+if [[ $use_backend == 0 ]]; then
+    if [[ $channel == "release" ]]; then
+        CARGO_INCREMENTAL=1 cargo rustc --release $flags
+    else
+        echo $LD_LIBRARY_PATH
+        cargo rustc $flags
+    fi
 fi
 
 if (( $build_only == 1 )); then
@@ -145,24 +169,26 @@ fi
 source config.sh
 
 function clean() {
-    rm -r target/out || true
-    mkdir -p target/out/gccjit
+    rm -r $cargo_target_dir || true
+    mkdir -p $cargo_target_dir/gccjit
 }
 
 function mini_tests() {
     echo "[BUILD] mini_core"
     crate_types="lib,dylib"
+
     if [[ "$HOST_TRIPLE" != "$TARGET_TRIPLE" ]]; then
         crate_types="lib"
     fi
-    $RUSTC example/mini_core.rs --crate-name mini_core --crate-type $crate_types --target $TARGET_TRIPLE
+
+    $RUST_CMD example/mini_core.rs --crate-name mini_core --crate-type $crate_types --target $TARGET_TRIPLE
 
     echo "[BUILD] example"
-    $RUSTC example/example.rs --crate-type lib --target $TARGET_TRIPLE
+    $RUST_CMD example/example.rs --crate-type lib --target $TARGET_TRIPLE
 
     echo "[AOT] mini_core_hello_world"
-    $RUSTC example/mini_core_hello_world.rs --crate-name mini_core_hello_world --crate-type bin -g --target $TARGET_TRIPLE
-    $RUN_WRAPPER ./target/out/mini_core_hello_world abc bcd
+    $RUST_CMD example/mini_core_hello_world.rs --crate-name mini_core_hello_world --crate-type bin -g --target $TARGET_TRIPLE
+    $RUN_WRAPPER $cargo_target_dir/mini_core_hello_world abc bcd
 }
 
 function build_sysroot() {
@@ -189,42 +215,42 @@ function run_in_vm() {
 
 function std_tests() {
     echo "[AOT] arbitrary_self_types_pointers_and_wrappers"
-    $RUSTC example/arbitrary_self_types_pointers_and_wrappers.rs --crate-name arbitrary_self_types_pointers_and_wrappers --crate-type bin --target $TARGET_TRIPLE
-    $RUN_WRAPPER ./target/out/arbitrary_self_types_pointers_and_wrappers
+    $RUST_CMD example/arbitrary_self_types_pointers_and_wrappers.rs --crate-name arbitrary_self_types_pointers_and_wrappers --crate-type bin --target $TARGET_TRIPLE
+    $RUN_WRAPPER $cargo_target_dir/arbitrary_self_types_pointers_and_wrappers
 
     echo "[AOT] alloc_system"
-    $RUSTC example/alloc_system.rs --crate-type lib --target "$TARGET_TRIPLE"
+    $RUST_CMD example/alloc_system.rs --crate-type lib --target "$TARGET_TRIPLE"
 
     # FIXME: doesn't work on m68k.
     if [[ "$HOST_TRIPLE" == "$TARGET_TRIPLE" ]]; then
         echo "[AOT] alloc_example"
-        $RUSTC example/alloc_example.rs --crate-type bin --target $TARGET_TRIPLE
-        $RUN_WRAPPER ./target/out/alloc_example
+        $RUST_CMD example/alloc_example.rs --crate-type bin --target $TARGET_TRIPLE
+        $RUN_WRAPPER $cargo_target_dir/alloc_example
     fi
 
     echo "[AOT] dst_field_align"
     # FIXME(antoyo): Re-add -Zmir-opt-level=2 once rust-lang/rust#67529 is fixed.
-    $RUSTC example/dst-field-align.rs --crate-name dst_field_align --crate-type bin --target $TARGET_TRIPLE
-    $RUN_WRAPPER ./target/out/dst_field_align || (echo $?; false)
+    $RUST_CMD example/dst-field-align.rs --crate-name dst_field_align --crate-type bin --target $TARGET_TRIPLE
+    $RUN_WRAPPER $cargo_target_dir/dst_field_align || (echo $?; false)
 
     echo "[AOT] std_example"
     std_flags="--cfg feature=\"master\""
     if (( $gcc_master_branch == 0 )); then
         std_flags=""
     fi
-    $RUSTC example/std_example.rs --crate-type bin --target $TARGET_TRIPLE $std_flags
-    $RUN_WRAPPER ./target/out/std_example --target $TARGET_TRIPLE
+    $RUST_CMD example/std_example.rs --crate-type bin --target $TARGET_TRIPLE $std_flags
+    $RUN_WRAPPER $cargo_target_dir/std_example --target $TARGET_TRIPLE
 
     echo "[AOT] subslice-patterns-const-eval"
-    $RUSTC example/subslice-patterns-const-eval.rs --crate-type bin $TEST_FLAGS --target $TARGET_TRIPLE
-    $RUN_WRAPPER ./target/out/subslice-patterns-const-eval
+    $RUST_CMD example/subslice-patterns-const-eval.rs --crate-type bin $TEST_FLAGS --target $TARGET_TRIPLE
+    $RUN_WRAPPER $cargo_target_dir/subslice-patterns-const-eval
 
     echo "[AOT] track-caller-attribute"
-    $RUSTC example/track-caller-attribute.rs --crate-type bin $TEST_FLAGS --target $TARGET_TRIPLE
-    $RUN_WRAPPER ./target/out/track-caller-attribute
+    $RUST_CMD example/track-caller-attribute.rs --crate-type bin $TEST_FLAGS --target $TARGET_TRIPLE
+    $RUN_WRAPPER $cargo_target_dir/track-caller-attribute
 
     echo "[BUILD] mod_bench"
-    $RUSTC example/mod_bench.rs --crate-type bin --target $TARGET_TRIPLE
+    $RUST_CMD example/mod_bench.rs --crate-type bin --target $TARGET_TRIPLE
 }
 
 function setup_rustc() {
@@ -233,7 +259,7 @@ function setup_rustc() {
     git clone https://github.com/rust-lang/rust.git || true
     cd rust
     git fetch
-    git checkout $(rustc -V | cut -d' ' -f3 | tr -d '(')
+    git checkout $($RUSTC -V | cut -d' ' -f3 | tr -d '(')
     export RUSTFLAGS=
 
     rm config.toml || true
@@ -258,8 +284,8 @@ llvm-filecheck = "`which FileCheck-10 || which FileCheck-11 || which FileCheck-1
 download-ci-llvm = false
 EOF
 
-    rustc -V | cut -d' ' -f3 | tr -d '('
-    git checkout $(rustc -V | cut -d' ' -f3 | tr -d '(') tests
+    $RUSTC -V | cut -d' ' -f3 | tr -d '('
+    git checkout $($RUSTC -V | cut -d' ' -f3 | tr -d '(') tests
 }
 
 function asm_tests() {
@@ -286,17 +312,17 @@ function test_libcore() {
 #echo "[BENCH COMPILE] mod_bench"
 
 #COMPILE_MOD_BENCH_INLINE="$RUSTC example/mod_bench.rs --crate-type bin -Zmir-opt-level=3 -O --crate-name mod_bench_inline"
-#COMPILE_MOD_BENCH_LLVM_0="rustc example/mod_bench.rs --crate-type bin -Copt-level=0 -o target/out/mod_bench_llvm_0 -Cpanic=abort"
-#COMPILE_MOD_BENCH_LLVM_1="rustc example/mod_bench.rs --crate-type bin -Copt-level=1 -o target/out/mod_bench_llvm_1 -Cpanic=abort"
-#COMPILE_MOD_BENCH_LLVM_2="rustc example/mod_bench.rs --crate-type bin -Copt-level=2 -o target/out/mod_bench_llvm_2 -Cpanic=abort"
-#COMPILE_MOD_BENCH_LLVM_3="rustc example/mod_bench.rs --crate-type bin -Copt-level=3 -o target/out/mod_bench_llvm_3 -Cpanic=abort"
+#COMPILE_MOD_BENCH_LLVM_0="rustc example/mod_bench.rs --crate-type bin -Copt-level=0 -o $cargo_target_dir/mod_bench_llvm_0 -Cpanic=abort"
+#COMPILE_MOD_BENCH_LLVM_1="rustc example/mod_bench.rs --crate-type bin -Copt-level=1 -o $cargo_target_dir/mod_bench_llvm_1 -Cpanic=abort"
+#COMPILE_MOD_BENCH_LLVM_2="rustc example/mod_bench.rs --crate-type bin -Copt-level=2 -o $cargo_target_dir/mod_bench_llvm_2 -Cpanic=abort"
+#COMPILE_MOD_BENCH_LLVM_3="rustc example/mod_bench.rs --crate-type bin -Copt-level=3 -o $cargo_target_dir/mod_bench_llvm_3 -Cpanic=abort"
 
 ## Use 100 runs, because a single compilations doesn't take more than ~150ms, so it isn't very slow
 #hyperfine --runs ${COMPILE_RUNS:-100} "$COMPILE_MOD_BENCH_INLINE" "$COMPILE_MOD_BENCH_LLVM_0" "$COMPILE_MOD_BENCH_LLVM_1" "$COMPILE_MOD_BENCH_LLVM_2" "$COMPILE_MOD_BENCH_LLVM_3"
 
 #echo
 #echo "[BENCH RUN] mod_bench"
-#hyperfine --runs ${RUN_RUNS:-10} ./target/out/mod_bench{,_inline} ./target/out/mod_bench_llvm_*
+#hyperfine --runs ${RUN_RUNS:-10} $cargo_target_dir/mod_bench{,_inline} $cargo_target_dir/mod_bench_llvm_*
 
 function extended_rand_tests() {
     if (( $gcc_master_branch == 0 )); then