diff --git a/src/shared/clang/clang_installation.pri b/src/shared/clang/clang_installation.pri
index 35474b8faa7..f3d5194d23f 100644
--- a/src/shared/clang/clang_installation.pri
+++ b/src/shared/clang/clang_installation.pri
@@ -101,6 +101,6 @@ isEmpty(LLVM_VERSION): error("Cannot determine clang version at $$LLVM_INSTALL_D
     error("LLVM/Clang version >= 3.9.0 required, version provided: $$LLVM_VERSION")
 }
 
-unix:LLVM_CXXFLAGS = -fno-rtti -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
+LLVM_CXXFLAGS = $$system($$llvm_config --cxxflags, lines)
 
 LLVM_IS_COMPILED_WITH_RTTI = $$system($$llvm_config --has-rtti, lines)
diff --git a/src/tools/clangrefactoringbackend/clangrefactoringbackend.pro b/src/tools/clangrefactoringbackend/clangrefactoringbackend.pro
index 072ed244dbe..518e203a4a4 100644
--- a/src/tools/clangrefactoringbackend/clangrefactoringbackend.pro
+++ b/src/tools/clangrefactoringbackend/clangrefactoringbackend.pro
@@ -16,7 +16,7 @@ QT -= gui
 LIBS += $$LIBTOOLING_LIBS
 INCLUDEPATH += $$LLVM_INCLUDEPATH
 
-QMAKE_CXXFLAGS += $$QMAKE_CXXFLAGS_RTTI_OFF $$LLVM_CXXFLAGS
+QMAKE_CXXFLAGS += $$LLVM_CXXFLAGS
 
 SOURCES += \
     clangrefactoringbackendmain.cpp