diff --git a/libgo/Makefile.am b/libgo/Makefile.am
index 48114d11d50..380caf53c6b 100644
--- a/libgo/Makefile.am
+++ b/libgo/Makefile.am
@@ -1812,7 +1812,7 @@ s-syscall_arch: Makefile
 
 sysinfo.go: s-sysinfo; @true
 s-sysinfo: $(srcdir)/mksysinfo.sh config.h
-	CC="$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(OSCFLAGS)" $(SHELL) $(srcdir)/mksysinfo.sh
+	CC="$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(OSCFLAGS) -O" $(SHELL) $(srcdir)/mksysinfo.sh
 	$(SHELL) $(srcdir)/mvifdiff.sh tmp-sysinfo.go sysinfo.go
 	$(STAMP) $@
 
diff --git a/libgo/Makefile.in b/libgo/Makefile.in
index 259d134c914..d495bf66dd7 100644
--- a/libgo/Makefile.in
+++ b/libgo/Makefile.in
@@ -4421,7 +4421,7 @@ s-syscall_arch: Makefile
 
 sysinfo.go: s-sysinfo; @true
 s-sysinfo: $(srcdir)/mksysinfo.sh config.h
-	CC="$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(OSCFLAGS)" $(SHELL) $(srcdir)/mksysinfo.sh
+	CC="$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(OSCFLAGS) -O" $(SHELL) $(srcdir)/mksysinfo.sh
 	$(SHELL) $(srcdir)/mvifdiff.sh tmp-sysinfo.go sysinfo.go
 	$(STAMP) $@