diff --git a/amazonlinux2/Makefile b/amazonlinux2/Makefile
index 8f938d5..c0a0f3b 100644
--- a/amazonlinux2/Makefile
+++ b/amazonlinux2/Makefile
@@ -34,8 +34,11 @@ PLATFORM=amazonlinux2
 PACKAGE_URL=https://swift.org/builds/$(BRANCH)/$(subst .,,$(PLATFORM))/swift-$(TARBALL_VERSION)-$(SNAPSHOT)/swift-$(TARBALL_VERSION)-$(SNAPSHOT)-$(PLATFORM).tar.gz
 
 HOST_SWIFT_TOOLCHAIN=/usr/local/lib/swift/xctoolchains/$(ARCH)-apple-darwin/$(HOST_VERSION)-current/swift.xctoolchain
+HOST_X_LLD=$(SWIFT_LIB_DIR)/clang-llvm/${HOST_PLATFORM}-apple-darwin/8.0.0/bin/lld
 
 
+INSTALL_PREFIX=$(BUILD_DIR)
+
 BUILD_DIR=$(PWD)/.build
 FETCH_DIR=$(PWD)/.fetch
 PATCH_DIR=$(BUILD_DIR)/patch
@@ -148,6 +151,8 @@ build-toolchain: $(PACKAGE_FETCH_FILE)
 	HOST_SWIFT_TOOLCHAIN=$(HOST_SWIFT_TOOLCHAIN)	\
 	TARGET_ARCH=$(ARCH)				\
 	TARGET_PLATFORM=$(PLATFORM)			\
+	HOST_X_LLD=$(HOST_X_LLD) \
+	INSTALL_PREFIX=$(INSTALL_PREFIX) \
 	./build-toolchain.sh $(PWD)/.fetch/swift-$(VERSION)-$(PLATFORM).tar.gz
 
 
diff --git a/amazonlinux2/build-toolchain.sh b/amazonlinux2/build-toolchain.sh
index 309aa88..887e1c9 100755
--- a/amazonlinux2/build-toolchain.sh
+++ b/amazonlinux2/build-toolchain.sh
@@ -27,7 +27,7 @@ SWIFT_LIB_DIR=${SWIFT_LIB_DIR:=/usr/local/lib/swift}
 # brew install swiftxcode/swiftxcode/clang-llvm-bin-8
 # ./retrieve-sdk-packages.sh
 HOST_SWIFT_TOOLCHAIN=${HOST_SWIFT_TOOLCHAIN:=${SWIFT_LIB_DIR}/xctoolchains/${HOST_PLATFORM}-apple-darwin/${SWIFT_VERSION}-current/swift.xctoolchain}
-HOST_X_LLD=${SWIFT_LIB_DIR}/clang-llvm/${HOST_PLATFORM}-apple-darwin/8.0.0/bin/lld
+HOST_X_LLD=${HOST_X_LLD:=${SWIFT_LIB_DIR}/clang-llvm/${HOST_PLATFORM}-apple-darwin/8.0.0/bin/lld}
 linux_sdk_name="${TARGET_ARCH}-${TARGET_PLATFORM}.sdk"
 LINUX_SDK="${BUILD_DIR}/${linux_sdk_name}"
 
diff --git a/ubuntu16.04/Makefile b/ubuntu16.04/Makefile
index 9529b2c..790d929 100644
--- a/ubuntu16.04/Makefile
+++ b/ubuntu16.04/Makefile
@@ -25,6 +25,11 @@ LINUX_TARGET_TRIPLE=$(ARCH)-linux-gnu
 PLATFORM=ubuntu16.04
 PACKAGE_URL=https://swift.org/builds/$(BRANCH)/$(subst .,,$(PLATFORM))/swift-$(VERSION)-$(SNAPSHOT)/swift-$(VERSION)-$(SNAPSHOT)-$(PLATFORM).tar.gz
 
+HOST_SWIFT_TOOLCHAIN=/usr/local/lib/swift/xctoolchains/$(ARCH)-apple-darwin/$(HOST_VERSION)-current/swift.xctoolchain
+HOST_X_LLD=$(SWIFT_LIB_DIR)/clang-llvm/${HOST_PLATFORM}-apple-darwin/8.0.0/bin/lld
+
+INSTALL_PREFIX=$(BUILD_DIR)
+
 BUILD_DIR=$(PWD)/.build
 FETCH_DIR=$(PWD)/.fetch
 PATCH_DIR=$(BUILD_DIR)/patch
@@ -109,7 +114,11 @@ retrieve-packages:
 # toolchain builder
 
 build-toolchain: $(PACKAGE_FETCH_FILE)
-	SWIFT_VERSION=$(VERSION) ./build-toolchain.sh $(PWD)/.fetch/swift-$(VERSION)-$(PLATFORM).tar.gz
+	SWIFT_VERSION=$(VERSION)			\
+	HOST_SWIFT_TOOLCHAIN=$(HOST_SWIFT_TOOLCHAIN)	\
+	HOST_X_LLD=$(HOST_X_LLD) \
+	INSTALL_PREFIX=$(INSTALL_PREFIX) \
+	./build-toolchain.sh $(PWD)/.fetch/swift-$(VERSION)-$(PLATFORM).tar.gz
 
 testbuild:
 	rm -rf my-test-app
@@ -138,4 +147,4 @@ testbuild-bash:
 		--workdir "/run" 		\
 		$(DOCKER_IMAGE) 		\
 		bash
-	
\ No newline at end of file
+	
diff --git a/ubuntu16.04/build-toolchain.sh b/ubuntu16.04/build-toolchain.sh
index 554a96a..d407126 100755
--- a/ubuntu16.04/build-toolchain.sh
+++ b/ubuntu16.04/build-toolchain.sh
@@ -26,8 +26,8 @@ SWIFT_LIB_DIR=${SWIFT_LIB_DIR:=/usr/local/lib/swift}
 # brew install swiftxcode/swiftxcode/swift-xctoolchain-5.3
 # brew install swiftxcode/swiftxcode/clang-llvm-bin-8
 # ./retrieve-sdk-packages.sh
-HOST_SWIFT_TOOLCHAIN=${SWIFT_LIB_DIR}/xctoolchains/${HOST_PLATFORM}-apple-darwin/${SWIFT_VERSION}-current/swift.xctoolchain
-HOST_X_LLD=${SWIFT_LIB_DIR}/clang-llvm/${HOST_PLATFORM}-apple-darwin/8.0.0/bin/lld
+HOST_SWIFT_TOOLCHAIN=${HOST_SWIFT_TOOLCHAIN:=${SWIFT_LIB_DIR}/xctoolchains/${HOST_PLATFORM}-apple-darwin/${SWIFT_VERSION}-current/swift.xctoolchain}
+HOST_X_LLD=${HOST_X_LLD:=${SWIFT_LIB_DIR}/clang-llvm/${HOST_PLATFORM}-apple-darwin/8.0.0/bin/lld}
 linux_sdk_name="${TARGET_ARCH}-${TARGET_PLATFORM}.sdk"
 LINUX_SDK="${BUILD_DIR}/${linux_sdk_name}"
 
diff --git a/ubuntu20.04/Makefile b/ubuntu20.04/Makefile
index 9f930da..a3b2d85 100644
--- a/ubuntu20.04/Makefile
+++ b/ubuntu20.04/Makefile
@@ -26,10 +26,16 @@ LINUX_TARGET_TRIPLE=$(ARCH)-linux-gnu
 PLATFORM=ubuntu20.04
 PACKAGE_URL=https://swift.org/builds/$(BRANCH)/$(subst .,,$(PLATFORM))/swift-$(VERSION)-$(SNAPSHOT)/swift-$(VERSION)-$(SNAPSHOT)-$(PLATFORM).tar.gz
 
+SWIFT_LIB_DIR=/usr/local/lib/swift
+HOST_SWIFT_TOOLCHAIN=/usr/local/lib/swift/xctoolchains/$(ARCH)-apple-darwin/$(HOST_VERSION)-current/swift.xctoolchain
+HOST_X_LLD=$(SWIFT_LIB_DIR)/clang-llvm/${HOST_PLATFORM}-apple-darwin/8.0.0/bin/lld
+
 BUILD_DIR=$(PWD)/.build
 FETCH_DIR=$(PWD)/.fetch
 PATCH_DIR=$(BUILD_DIR)/patch
 
+INSTALL_PREFIX=$(BUILD_DIR)
+
 DESTDIR_PREFIX=$(prefix)/lib/swift/dst/x86_64-unknown-linux/
 
 PACKAGE_FETCH_FILENAME=swift-$(VERSION)-$(PLATFORM).tar.gz
@@ -106,7 +112,11 @@ retrieve-packages:
 # toolchain builder
 
 build-toolchain: $(PACKAGE_FETCH_FILE)
-	SWIFT_VERSION=$(MAIN_VERSION) ./build-toolchain.sh $(PWD)/.fetch/swift-$(VERSION)-$(PLATFORM).tar.gz
+	HOST_SWIFT_TOOLCHAIN=$(HOST_SWIFT_TOOLCHAIN) \
+	HOST_X_LLD=$(HOST_X_LLD) \
+	SWIFT_VERSION=$(MAIN_VERSION) \
+	INSTALL_PREFIX=$(INSTALL_PREFIX) \
+	./build-toolchain.sh $(PWD)/.fetch/swift-$(VERSION)-$(PLATFORM).tar.gz
 
 testbuild:
 	rm -rf my-test-app
diff --git a/ubuntu20.04/build-toolchain.sh b/ubuntu20.04/build-toolchain.sh
index 8da15b4..016f7eb 100755
--- a/ubuntu20.04/build-toolchain.sh
+++ b/ubuntu20.04/build-toolchain.sh
@@ -26,8 +26,10 @@ SWIFT_LIB_DIR=${SWIFT_LIB_DIR:=/usr/local/lib/swift}
 # brew install swiftxcode/swiftxcode/swift-xctoolchain-5.3
 # brew install swiftxcode/swiftxcode/clang-llvm-bin-8
 # ./retrieve-sdk-packages.sh
-HOST_SWIFT_TOOLCHAIN=${SWIFT_LIB_DIR}/xctoolchains/${HOST_PLATFORM}-apple-darwin/${SWIFT_VERSION}-current/swift.xctoolchain
-HOST_X_LLD=${SWIFT_LIB_DIR}/clang-llvm/${HOST_PLATFORM}-apple-darwin/8.0.0/bin/lld
+HOST_SWIFT_TOOLCHAIN=${HOST_SWIFT_TOOLCHAIN:=${SWIFT_LIB_DIR}/xctoolchains/${HOST_PLATFORM}-apple-darwin/${SWIFT_VERSION}-current/swift.xctoolchain}
+
+HOST_X_LLD=${HOST_X_LLD:=${SWIFT_LIB_DIR}/clang-llvm/${HOST_PLATFORM}-apple-darwin/8.0.0/bin/lld}
+  
 linux_sdk_name="${TARGET_ARCH}-${TARGET_PLATFORM}.sdk"
 LINUX_SDK="${BUILD_DIR}/${linux_sdk_name}"