--- a/js/src/Makefile.in
+++ b/js/src/Makefile.in
@@ -684,25 +684,27 @@ endif
 
 ifdef MOZ_MEMORY
 ifeq ($(OS_ARCH),Darwin)
 LDFLAGS += -ljemalloc
 endif
 endif
 
 ifdef SOLARIS_SUNPRO_CXX
+ifeq ($(TARGET_CPU),sparc
 # Sun Studio SPARC doesn't work well with gcc inline asm, use lock_SunOS_sparc*.il
 jslock.o: jslock.cpp Makefile.in lock_sparcv8plus.il lock_sparcv9.il
 	$(REPORT_BUILD)
 	@$(MAKE_DEPS_AUTO_CXX)
 ifeq (sparcv9,$(findstring sparcv9,$(OS_TEST)))
 	$(CXX) -o $@ -c $(COMPILE_CFLAGS) $(srcdir)/lock_sparcv9.il $<
 else
 	$(CXX) -o $@ -c $(COMPILE_CFLAGS) $(srcdir)/lock_sparcv8plus.il $<
 endif # sparcv9
+endif # sparc
 endif # SOLARIS_SUNPRO_CXX
 
 ifeq ($(OS_ARCH),IRIX)
 ifndef GNU_CC
 _COMPILE_CFLAGS  = $(patsubst -O%,-O1,$(COMPILE_CFLAGS))
 jsapi.o jsxdrapi.o jsarena.o jsarray.o jsatom.o jsemit.o jsfun.o jsinterp.o jsreflect.o jsregexp.o jsparse.o jsopcode.o jsscript.o: %.o: %.cpp Makefile.in
 	$(REPORT_BUILD)
 	@$(MAKE_DEPS_AUTO_CXX)