diff --git a/debian/rules b/debian/rules
index 1cfc778d..57d966fe 100755
--- a/debian/rules
+++ b/debian/rules
@@ -39,43 +39,42 @@ include /usr/share/dpkg/architecture.mk
 
 CONFIGURE_EXTRA =
 
-# set up global build flags (dpkg-buildflags)
+# dpkg-buildflags support
 # disable lto
-export DEB_BUILD_MAINT_OPTIONS=optimize=-lto
+export DEB_BUILD_MAINT_OPTIONS = optimize=-lto
 # these are handled on a per stage / build basis
-export DEB_CFLAGS_MAINT_STRIP=-g -O2
-export DEB_CXXFLAGS_MAINT_STRIP=-g -O2
-# additional global build flags
-export DEB_CFLAGS_MAINT_APPEND=-Wno-unused-command-line-argument
-export DEB_CXXFLAGS_MAINT_APPEND=-Wno-unused-command-line-argument
-export DEB_LDFLAGS_MAINT_APPEND=-Wl,--build-id
+export DEB_CFLAGS_MAINT_STRIP = -g -O2
+export DEB_CXXFLAGS_MAINT_STRIP = -g -O2
 
-# all stages all builds
-CFLAGS_EXTRA = $(shell dpkg-buildflags --get CFLAGS) $(shell dpkg-buildflags --get CPPFLAGS)
-CXXFLAGS_EXTRA = $(shell dpkg-buildflags --get CXXFLAGS) $(shell dpkg-buildflags --get CPPFLAGS)
-LDFLAGS_EXTRA = $(shell dpkg-buildflags --get LDFLAGS)
+include /usr/share/dpkg/buildflags.mk
 
 # We use a stage2 build. It means that a first clang is built using gcc,
 # a second clang is built with the first
 # And the various compoments are built using the second clang.
 # See https://llvm.org/docs/AdvancedBuilds.html
 
-# stage 1 toolchain build only
-STAGE_1_CFLAGS_EXTRA = $(CFLAGS_EXTRA)
-STAGE_1_CXXFLAGS_EXTRA = $(CXXFLAGS_EXTRA)
-STAGE_1_LDFLAGS_EXTRA = $(LDFLAGS_EXTRA)
-# stage 2 toolchain and stand-alone builds
-STAGE_2_CFLAGS_EXTRA = $(CFLAGS_EXTRA)
-STAGE_2_CXXFLAGS_EXTRA = $(CXXFLAGS_EXTRA)
-STAGE_2_LDFLAGS_EXTRA = $(LDFLAGS_EXTRA)
+# collect additional flags for all stages all builds
+CFLAGS_EXTRA = -Wno-unused-command-line-argument
+CXXFLAGS_EXTRA = -Wno-unused-command-line-argument
+LDFLAGS_EXTRA = -Wl,--build-id
 
-# toolchain build cmake options
+# collect all flags for stage 1 toolchain build only
+STAGE_1_CFLAGS = $(CFLAGS) $(CFLAGS_EXTRA) $(CPPFLAGS)
+STAGE_1_CXXFLAGS = $(CXXFLAGS) $(CXXFLAGS_EXTRA) $(CPPFLAGS)
+STAGE_1_LDFLAGS = $(LDFLAGS) $(LDFLAGS_EXTRA)
+
+# collect all flags for stage 2 toolchain and stand-alone builds
+STAGE_2_CFLAGS = $(CFLAGS) $(CFLAGS_EXTRA) $(CPPFLAGS)
+STAGE_2_CXXFLAGS = $(CXXFLAGS) $(CXXFLAGS_EXTRA) $(CPPFLAGS)
+STAGE_2_LDFLAGS = $(LDFLAGS) $(LDFLAGS_EXTRA)
+
+# collect additional cmake options for toolchain build configuration
 STAGE_1_CMAKE_EXTRA =
 STAGE_2_CMAKE_EXTRA = -DPYTHON_EXECUTABLE=/usr/bin/python3
 STAGE_ALL_CMAKE_EXTRA =
-# build-only var combining all first stage cmake options
+# toolchain config-only var combining all stage 1 cmake options
 CMAKE_EXTRA = $(STAGE_1_CMAKE_EXTRA) $(STAGE_ALL_CMAKE_EXTRA)
-# build-only var prepending BOOTSTRAP_ prefix to all stage 2 cmake vars
+# toolchain config-only var prepending BOOTSTRAP_ to all stage 2 cmake options
 BOOTSTRAP_CMAKE_EXTRA = $(foreach extra,$(STAGE_2_CMAKE_EXTRA) $(STAGE_ALL_CMAKE_EXTRA), $(subst -D,-DBOOTSTRAP_,$(extra)))
 
 BASE_PATH := $(CURDIR)
@@ -470,20 +469,17 @@ override_dh_auto_configure: preconfigure
 
 	echo "Running tests: $(RUN_TEST)"
 	echo "Using cmake: $(CMAKE_BIN)"; \
-	CFLAGS="$(CFLAGS_EXTRA)" \
-	CXXFLAGS="$(CXXFLAGS_EXTRA)"  \
-	LDFLAGS="$(LDFLAGS_EXTRA)" \
 	LD_LIBRARY_PATH=$$LD_LIBRARY_PATH \
 	$(PRE_PROCESS_CONF) $(CMAKE_BIN) -S llvm/ -B $(TARGET_BUILD) \
 	-G $(GENERATOR) \
 	-DCMAKE_INSTALL_PREFIX=/usr/lib/llvm-$(LLVM_VERSION) \
 	-DCMAKE_SUPPRESS_REGENERATION=ON \
 	-DCMAKE_BUILD_TYPE=Release \
-	-DCMAKE_C_FLAGS="$(STAGE_1_CFLAGS_EXTRA)" \
-	-DCMAKE_CXX_FLAGS="$(STAGE_1_CXXFLAGS_EXTRA)" \
-	-DCMAKE_SHARED_LINKER_FLAGS="$(STAGE_1_LDFLAGS_EXTRA)" \
-	-DCMAKE_MODULE_LINKER_FLAGS="$(STAGE_1_LDFLAGS_EXTRA)" \
-	-DCMAKE_EXE_LINKER_FLAGS="$(STAGE_1_LDFLAGS_EXTRA)" \
+	-DCMAKE_C_FLAGS="$(STAGE_1_CFLAGS)" \
+	-DCMAKE_CXX_FLAGS="$(STAGE_1_CXXFLAGS)" \
+	-DCMAKE_SHARED_LINKER_FLAGS="$(STAGE_1_LDFLAGS)" \
+	-DCMAKE_MODULE_LINKER_FLAGS="$(STAGE_1_LDFLAGS)" \
+	-DCMAKE_EXE_LINKER_FLAGS="$(STAGE_1_LDFLAGS)" \
 	-DPACKAGE_VENDOR=$(VENDOR) \
 	-DENABLE_LINKER_BUILD_ID=ON \
 	-DLLVM_TARGETS_TO_BUILD=Native \
@@ -523,18 +519,18 @@ override_dh_auto_configure: preconfigure
 	-DLIBOMP_ENABLE_RTTI=OFF \
 	-DLIBOMP_OMPT_SUPPORT=OFF \
 	$(CMAKE_EXTRA) \
-	-DBUILTINS_CMAKE_ARGS="-DCMAKE_C_FLAGS=$(STAGE_1_CFLAGS_EXTRA);-DCMAKE_CXX_FLAGS=$(STAGE_1_CXXFLAGS_EXTRA);-DCMAKE_EXE_LINKER_FLAGS=$(STAGE_1_LDFLAGS_EXTRA);-DCMAKE_SHARED_LINKER_FLAGS=$(STAGE_1_LDFLAGS_EXTRA);-DCMAKE_MODULE_LINKER_FLAGS=$(STAGE_1_LDFLAGS_EXTRA);-DCMAKE_SYSTEM_NAME=Linux;-DCMAKE_BUILD_TYPE=Release;-DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF" \
-	-DRUNTIMES_CMAKE_ARGS="-DCMAKE_C_FLAGS=$(STAGE_1_CFLAGS_EXTRA);-DCMAKE_CXX_FLAGS=$(STAGE_1_CXXFLAGS_EXTRA);-DCMAKE_EXE_LINKER_FLAGS=$(STAGE_1_LDFLAGS_EXTRA);-DCMAKE_SHARED_LINKER_FLAGS=$(STAGE_1_LDFLAGS_EXTRA);-DCMAKE_MODULE_LINKER_FLAGS=$(STAGE_1_LDFLAGS_EXTRA);-DCMAKE_SYSTEM_NAME=Linux;-DCMAKE_BUILD_TYPE=Release;-DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF" \
+	-DBUILTINS_CMAKE_ARGS="-DCMAKE_C_FLAGS=$(STAGE_1_CFLAGS);-DCMAKE_CXX_FLAGS=$(STAGE_1_CXXFLAGS);-DCMAKE_EXE_LINKER_FLAGS=$(STAGE_1_LDFLAGS);-DCMAKE_SHARED_LINKER_FLAGS=$(STAGE_1_LDFLAGS);-DCMAKE_MODULE_LINKER_FLAGS=$(STAGE_1_LDFLAGS);-DCMAKE_SYSTEM_NAME=Linux;-DCMAKE_BUILD_TYPE=Release;-DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF" \
+	-DRUNTIMES_CMAKE_ARGS="-DCMAKE_C_FLAGS=$(STAGE_1_CFLAGS);-DCMAKE_CXX_FLAGS=$(STAGE_1_CXXFLAGS);-DCMAKE_EXE_LINKER_FLAGS=$(STAGE_1_LDFLAGS);-DCMAKE_SHARED_LINKER_FLAGS=$(STAGE_1_LDFLAGS);-DCMAKE_MODULE_LINKER_FLAGS=$(STAGE_1_LDFLAGS);-DCMAKE_SYSTEM_NAME=Linux;-DCMAKE_BUILD_TYPE=Release;-DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF" \
 	-DCLANG_ENABLE_BOOTSTRAP=ON \
 	-DCLANG_BOOTSTRAP_TARGETS="$(ENABLED_STAGE2_CMAKE_BUILD_TARGETS)" \
 	-DBOOTSTRAP_CMAKE_BUILD_TYPE=RelWithDebInfo \
 	-DBOOTSTRAP_CMAKE_C_FLAGS_RELWITHDEBINFO="$(opt_flags)" \
 	-DBOOTSTRAP_CMAKE_CXX_FLAGS_RELWITHDEBINFO="$(opt_flags)" \
-	-DBOOTSTRAP_CMAKE_C_FLAGS="$(STAGE_2_CFLAGS_EXTRA)" \
-	-DBOOTSTRAP_CMAKE_CXX_FLAGS="$(STAGE_2_CXXFLAGS_EXTRA)" \
-	-DBOOTSTRAP_CMAKE_SHARED_LINKER_FLAGS="$(STAGE_2_LDFLAGS_EXTRA)" \
-	-DBOOTSTRAP_CMAKE_MODULE_LINKER_FLAGS="$(STAGE_2_LDFLAGS_EXTRA)" \
-	-DBOOTSTRAP_CMAKE_EXE_LINKER_FLAGS="$(STAGE_2_LDFLAGS_EXTRA)" \
+	-DBOOTSTRAP_CMAKE_C_FLAGS="$(STAGE_2_CFLAGS)" \
+	-DBOOTSTRAP_CMAKE_CXX_FLAGS="$(STAGE_2_CXXFLAGS)" \
+	-DBOOTSTRAP_CMAKE_SHARED_LINKER_FLAGS="$(STAGE_2_LDFLAGS)" \
+	-DBOOTSTRAP_CMAKE_MODULE_LINKER_FLAGS="$(STAGE_2_LDFLAGS)" \
+	-DBOOTSTRAP_CMAKE_EXE_LINKER_FLAGS="$(STAGE_2_LDFLAGS)" \
 	-DBOOTSTRAP_LLVM_ENABLE_FFI=ON \
 	-DBOOTSTRAP_LLVM_ENABLE_DUMP=ON \
 	-DBOOTSTRAP_LLVM_ENABLE_LIBPFM=ON \
@@ -550,8 +546,8 @@ override_dh_auto_configure: preconfigure
 	-DBOOTSTRAP_LIBCLANG_LIBRARY_VERSION=$(SONAME_EXT) \
 	-DBOOTSTRAP_LIBCXX_INSTALL_EXPERIMENTAL_LIBRARY=ON \
 	$(BOOTSTRAP_CMAKE_EXTRA) \
-	-DBOOTSTRAP_BUILTINS_CMAKE_ARGS="-DCMAKE_C_FLAGS=$(STAGE_2_CFLAGS_EXTRA);-DCMAKE_CXX_FLAGS=$(STAGE_2_CXXFLAGS_EXTRA);-DCMAKE_EXE_LINKER_FLAGS=$(STAGE_2_LDFLAGS_EXTRA);-DCMAKE_SHARED_LINKER_FLAGS=$(STAGE_2_LDFLAGS_EXTRA);-DCMAKE_MODULE_LINKER_FLAGS=$(STAGE_2_LDFLAGS_EXTRA);-DCMAKE_SYSTEM_NAME=Linux;-DCMAKE_BUILD_TYPE=RelWithDebInfo;-DCMAKE_C_FLAGS_RELWITHDEBINFO=$(opt_flags);-DCMAKE_CXX_FLAGS_RELWITHDEBINFO=$(opt_flags);-DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF" \
-	-DBOOTSTRAP_RUNTIMES_CMAKE_ARGS="-DCMAKE_C_FLAGS=$(STAGE_2_CFLAGS_EXTRA);-DCMAKE_CXX_FLAGS=$(STAGE_2_CXXFLAGS_EXTRA);-DCMAKE_EXE_LINKER_FLAGS=$(STAGE_2_LDFLAGS_EXTRA) -L$(STAGE_1_LIB_DIR);-DCMAKE_SHARED_LINKER_FLAGS=$(STAGE_2_LDFLAGS_EXTRA) -L$(STAGE_1_LIB_DIR);-DCMAKE_MODULE_LINKER_FLAGS=$(STAGE_2_LDFLAGS_EXTRA) -L$(STAGE_1_LIB_DIR);-DCMAKE_SYSTEM_NAME=Linux;-DCMAKE_BUILD_TYPE=RelWithDebInfo;-DCMAKE_C_FLAGS_RELWITHDEBINFO=$(opt_flags);-DCMAKE_CXX_FLAGS_RELWITHDEBINFO=$(opt_flags);-DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF" \
+	-DBOOTSTRAP_BUILTINS_CMAKE_ARGS="-DCMAKE_C_FLAGS=$(STAGE_2_CFLAGS);-DCMAKE_CXX_FLAGS=$(STAGE_2_CXXFLAGS);-DCMAKE_EXE_LINKER_FLAGS=$(STAGE_2_LDFLAGS);-DCMAKE_SHARED_LINKER_FLAGS=$(STAGE_2_LDFLAGS);-DCMAKE_MODULE_LINKER_FLAGS=$(STAGE_2_LDFLAGS);-DCMAKE_SYSTEM_NAME=Linux;-DCMAKE_BUILD_TYPE=RelWithDebInfo;-DCMAKE_C_FLAGS_RELWITHDEBINFO=$(opt_flags);-DCMAKE_CXX_FLAGS_RELWITHDEBINFO=$(opt_flags);-DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF" \
+	-DBOOTSTRAP_RUNTIMES_CMAKE_ARGS="-DCMAKE_C_FLAGS=$(STAGE_2_CFLAGS);-DCMAKE_CXX_FLAGS=$(STAGE_2_CXXFLAGS);-DCMAKE_EXE_LINKER_FLAGS=$(STAGE_2_LDFLAGS) -L$(STAGE_1_LIB_DIR);-DCMAKE_SHARED_LINKER_FLAGS=$(STAGE_2_LDFLAGS) -L$(STAGE_1_LIB_DIR);-DCMAKE_MODULE_LINKER_FLAGS=$(STAGE_2_LDFLAGS) -L$(STAGE_1_LIB_DIR);-DCMAKE_SYSTEM_NAME=Linux;-DCMAKE_BUILD_TYPE=RelWithDebInfo;-DCMAKE_C_FLAGS_RELWITHDEBINFO=$(opt_flags);-DCMAKE_CXX_FLAGS_RELWITHDEBINFO=$(opt_flags);-DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF" \
 	-DCLANG_BOOTSTRAP_PASSTHROUGH="CMAKE_INSTALL_PREFIX;CMAKE_SUPPRESS_REGENERATION;ENABLE_LINKER_BUILD_ID;LLVM_ENABLE_PIC;LLVM_ENABLE_RTTI;LLVM_INCLUDE_GO_TESTS;CLANG_DEFAULT_LINKER;CLANG_DEFAULT_CXX_STDLIB;CLANG_DEFAULT_RTLIB;COMPILER_RT_USE_LIBCXX;COMPILER_RT_USE_BUILTINS_LIBRARY;COMPILER_RT_INCLUDE_TESTS;LIBUNWIND_ENABLE_SHARED;LIBUNWIND_USE_COMPILER_RT;LIBCXXABI_ENABLE_SHARED;LIBCXXABI_ENABLE_EXCEPTIONS;LIBCXXABI_USE_COMPILER_RT;LIBCXX_USE_COMPILER_RT;LIBCXX_ENABLE_SHARED;LIBCXX_ENABLE_EXCEPTIONS;LIBCXX_ENABLE_STATIC_ABI_LIBRARY;LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY;LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY;LIBOMP_ENABLE_RTTI;PYTHON_EXECUTABLE"
 	FOUND_VERSION=`grep LLVM_VERSION_STRING build-llvm/include/llvm/Config/llvm-config.h|cut -d\" -f2`; \
 	if ! echo "$(LLVM_VERSION_FULL)"|grep "$$FOUND_VERSION"; then \
@@ -582,7 +578,7 @@ debian-full-build:
 debian-libfuzzer-build:
 ifeq (${LIBFUZZER_ENABLE},yes)
 	cd $(TARGET_BUILD); \
-	CFLAGS="$(opt_flags) $(STAGE_2_CFLAGS_EXTRA)"; \
+	CFLAGS="$(opt_flags) $(STAGE_2_CFLAGS)"; \
 	echo $$CFLAGS; \
 	$(STAGE_2_BIN_DIR)/clang++ -c $$CFLAGS -std=c++11 $(BASE_PATH)/compiler-rt/lib/fuzzer/*.cpp -IFuzzer; \
 	ar ruv libFuzzer.a Fuzzer*.o
@@ -598,11 +594,11 @@ debian-libclc-build:
 	-G $(GENERATOR) \
 	-DCMAKE_C_COMPILER=$(STAGE_2_BIN_DIR)/clang \
 	-DCMAKE_CXX_COMPILER=$(STAGE_2_BIN_DIR)/clang++ \
-	-DCMAKE_C_FLAGS="$(opt_flags) $(STAGE_2_CFLAGS_EXTRA)" \
-	-DCMAKE_CXX_FLAGS="$(opt_flags) $(STAGE_2_CXXFLAGS_EXTRA)" \
-	-DCMAKE_SHARED_LINKER_FLAGS="$(STAGE_2_LDFLAGS_EXTRA) -L$(STAGE_2_LIB_DIR)" \
-	-DCMAKE_MODULE_LINKER_FLAGS="$(STAGE_2_LDFLAGS_EXTRA) -L$(STAGE_2_LIB_DIR)" \
-	-DCMAKE_EXE_LINKER_FLAGS="$(STAGE_2_LDFLAGS_EXTRA) -L$(STAGE_2_LIB_DIR)" \
+	-DCMAKE_C_FLAGS="$(opt_flags) $(STAGE_2_CFLAGS)" \
+	-DCMAKE_CXX_FLAGS="$(opt_flags) $(STAGE_2_CXXFLAGS)" \
+	-DCMAKE_SHARED_LINKER_FLAGS="$(STAGE_2_LDFLAGS) -L$(STAGE_2_LIB_DIR)" \
+	-DCMAKE_MODULE_LINKER_FLAGS="$(STAGE_2_LDFLAGS) -L$(STAGE_2_LIB_DIR)" \
+	-DCMAKE_EXE_LINKER_FLAGS="$(STAGE_2_LDFLAGS) -L$(STAGE_2_LIB_DIR)" \
 	-DCMAKE_INSTALL_PREFIX=/usr \
 	-DCMAKE_INSTALL_DATADIR=lib \
 	-DCMAKE_INSTALL_INCLUDEDIR=include \