-CPP.Flags += -I$(LLVM_SRC_ROOT)/utils/unittest/googletest/include/
-CPP.Flags += $(NO_VARIADIC_MACROS)
+# Note that these flags are duplicated when building GoogleTest itself in
+# utils/unittest/googletest/Makefile; ensure that any changes are made to both.
+CPP.Flags += -I$(LLVM_SRC_ROOT)/utils/unittest/googletest/include
+CPP.Flags += $(NO_MISSING_FIELD_INITIALIZERS) $(NO_VARIADIC_MACROS)
+CPP.Flags += -DGTEST_HAS_RTTI=0
+# libstdc++'s TR1 <tuple> header depends on RTTI and uses C++'0x features not
+# supported by Clang, so force googletest to use its own tuple implementation.
+CPP.Flags += -DGTEST_USE_OWN_TR1_TUPLE
+
+# Disable pthreads if LLVM was configured without them.
+ifneq ($(HAVE_PTHREAD), 1)
+ CPP.Flags += -DGTEST_HAS_PTHREAD=0
+endif
+