2 files changed, 31 insertions, 10 deletions
diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
index 071312f5eb92..0efb8f2b33ce 100644
--- a/tools/scripts/Makefile.include
+++ b/tools/scripts/Makefile.include
@@ -52,11 +52,17 @@ define allow-override
 endef
 
 ifneq ($(LLVM),)
-$(call allow-override,CC,clang)
-$(call allow-override,AR,llvm-ar)
-$(call allow-override,LD,ld.lld)
-$(call allow-override,CXX,clang++)
-$(call allow-override,STRIP,llvm-strip)
+ifneq ($(filter %/,$(LLVM)),)
+LLVM_PREFIX := $(LLVM)
+else ifneq ($(filter -%,$(LLVM)),)
+LLVM_SUFFIX := $(LLVM)
+endif
+
+$(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
+$(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
+$(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
+$(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX))
+$(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
 else
 # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
 $(call allow-override,CC,$(CROSS_COMPILE)gcc)
@@ -69,9 +75,9 @@ endif
 CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
 
 ifneq ($(LLVM),)
-HOSTAR  ?= llvm-ar
-HOSTCC  ?= clang
-HOSTLD  ?= ld.lld
+HOSTAR  ?= $(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)
+HOSTCC  ?= $(LLVM_PREFIX)clang$(LLVM_SUFFIX)
+HOSTLD  ?= $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)
 else
 HOSTAR  ?= ar
 HOSTCC  ?= gcc
@@ -87,7 +93,22 @@ LLVM_STRIP	?= llvm-strip
 
 ifeq ($(CC_NO_CLANG), 1)
 EXTRA_WARNINGS += -Wstrict-aliasing=3
-endif
+
+else ifneq ($(CROSS_COMPILE),)
+# Allow userspace to override CLANG_CROSS_FLAGS to specify their own
+# sysroots and flags or to avoid the GCC call in pure Clang builds.
+ifeq ($(CLANG_CROSS_FLAGS),)
+CLANG_CROSS_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%))
+GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc 2>/dev/null))
+ifneq ($(GCC_TOOLCHAIN_DIR),)
+CLANG_CROSS_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
+CLANG_CROSS_FLAGS += --sysroot=$(shell $(CROSS_COMPILE)gcc -print-sysroot)
+CLANG_CROSS_FLAGS += --gcc-toolchain=$(realpath $(GCC_TOOLCHAIN_DIR)/..)
+endif # GCC_TOOLCHAIN_DIR
+endif # CLANG_CROSS_FLAGS
+CFLAGS += $(CLANG_CROSS_FLAGS)
+AFLAGS += $(CLANG_CROSS_FLAGS)
+endif # CROSS_COMPILE
 
 # Hack to avoid type-punned warnings on old systems such as RHEL5:
 # We should be changing CFLAGS and checking gcc version, but this
diff --git a/tools/scripts/utilities.mak b/tools/scripts/utilities.mak
index c16ce833079c..172e47273b5d 100644
--- a/tools/scripts/utilities.mak
+++ b/tools/scripts/utilities.mak
@@ -175,5 +175,5 @@ _ge-abspath = $(if $(is-executable),$(1))
 define get-executable-or-default
 $(if $($(1)),$(call _ge_attempt,$($(1)),$(1)),$(call _ge_attempt,$(2)))
 endef
-_ge_attempt = $(if $(get-executable),$(get-executable),$(call _gea_err,$(2)))
+_ge_attempt = $(or $(get-executable),$(call _gea_err,$(2)))
 _gea_err  = $(if $(1),$(error Please set '$(1)' appropriately))