diff -urpN newlib-1.17.0.orig/config/mt-d30v newlib-1.17.0/config/mt-d30v
--- newlib-1.17.0.orig/config/mt-d30v	2017-04-11 00:51:26.572757941 -0700
+++ newlib-1.17.0/config/mt-d30v	2017-04-11 00:55:51.110626527 -0700
@@ -1,4 +1,4 @@
 # Build libraries optimizing for space, not speed.
 # Turn off warnings about symbols named the same as registers
- CFLAGS_FOR_TARGET = -g -Os -Wa,-C
- CXXFLAGS_FOR_TARGET = -g -Os -Wa,-C
+ CFLAGS_FOR_TARGET += -g -Os -Wa,-C
+ CXXFLAGS_FOR_TARGET += -g -Os -Wa,-C
diff -urpN newlib-1.17.0.orig/config/mt-gnu newlib-1.17.0/config/mt-gnu
--- newlib-1.17.0.orig/config/mt-gnu	2017-04-11 00:51:26.572757941 -0700
+++ newlib-1.17.0/config/mt-gnu	2017-04-11 00:55:51.110626527 -0700
@@ -1,2 +1,2 @@
-CXXFLAGS_FOR_TARGET = $(CXXFLAGS) $(SYSROOT_CFLAGS_FOR_TARGET) \
+CXXFLAGS_FOR_TARGET += $(CXXFLAGS) $(SYSROOT_CFLAGS_FOR_TARGET) \
 	$(DEBUG_PREFIX_CFLAGS_FOR_TARGET) -D_GNU_SOURCE
diff -urpN newlib-1.17.0.orig/config/mt-ospace newlib-1.17.0/config/mt-ospace
--- newlib-1.17.0.orig/config/mt-ospace	2017-04-11 00:51:26.572757941 -0700
+++ newlib-1.17.0/config/mt-ospace	2017-04-11 00:55:51.110626527 -0700
@@ -1,3 +1,3 @@
 # Build libraries optimizing for space, not speed.
- CFLAGS_FOR_TARGET = -g -Os
- CXXFLAGS_FOR_TARGET = -g -Os
+ CFLAGS_FOR_TARGET += -g -Os
+ CXXFLAGS_FOR_TARGET += -g -Os