-LLVM_SRC_ROOT := $(shell cd @abs_top_srcdir@; $(PWD))
-LLVM_OBJ_ROOT := $(shell cd @abs_top_builddir@; $(PWD))
-PROJ_SRC_ROOT := $(shell cd $(LLVM_SRC_ROOT); $(PWD))
-PROJ_SRC_DIR := $(shell cd $(LLVM_SRC_ROOT)/$(patsubst $(PROJ_OBJ_ROOT)%,%,$(PROJ_OBJ_DIR)); $(PWD))
+LLVM_SRC_ROOT := $(call realpath, @abs_top_srcdir@)
+LLVM_OBJ_ROOT := $(call realpath, @abs_top_builddir@)
+PROJ_SRC_ROOT := $(LLVM_SRC_ROOT)
+PROJ_SRC_DIR := $(call realpath, $(LLVM_SRC_ROOT)/$(patsubst $(PROJ_OBJ_ROOT)%,%,$(PROJ_OBJ_DIR)))