--- a/gcc/config/t-vxworks	Thu Oct 25 07:37:49 2018 +0900
+++ b/gcc/config/t-vxworks	Thu Feb 13 11:34:05 2020 +0900
@@ -1,4 +1,4 @@
-# Copyright (C) 2002-2018 Free Software Foundation, Inc.
+# Copyright (C) 2002-2020 Free Software Foundation, Inc.
 #
 # This file is part of GCC.
 #
@@ -16,9 +16,56 @@
 # along with GCC; see the file COPYING3.  If not see
 # <http://www.gnu.org/licenses/>.
 
-# Both the kernel and RTP headers provide limits.h.
+vxworks.o: $(srcdir)/config/vxworks.c
+	$(COMPILE) $<
+	$(POSTCOMPILE)
+
+vxworks-c.o: $(srcdir)/config/vxworks-c.c
+	$(COMPILE) $<
+	$(POSTCOMPILE)
+
+# Arrange to install our stdint.h wrapper, by copying it in the
+# build-time include dir before this include dir is installed and after
+# stmp-int-hdrs removes it (because it was told we don't provide it).
+
+INSTALL_HEADERS += install-stdint.h
+
+install-stdint.h: stmp-int-hdrs
+	cp -p $(srcdir)/config/vxworks/stdint.h include/stdint.h
+	chmod a+r include/stdint.h
+
+$(INSTALL_HEADERS_DIR): install-stdint.h
+
+# Both the kernel and RTP headers provide limits.h.  They embed VxWorks
+# specificities and are dated on some configurations so we both need to
+# provide our own version and make sure the system one gets exposed.
+
 LIMITS_H_TEST = true
+STMP_FIXINC = stmp-fixinc
 
-vxworks.o: $(srcdir)/config/vxworks.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
-	$(TARGET_H) output.h $(TM_H)
-	$(COMPILER) -c $(ALL_COMPILERFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) $<
+# VxWorks system environments have been GCC based for a long time and we need
+# to make sure that our files and the system ones use distinct macro names to
+# protect against recursive inclusions.  We achieve this by temporarily
+# substituting the headers used by stmp-int-headers with alternative versions
+# where we add some version indication in the inclusion-protection macro
+# names.
+
+# Before the standard stmp-int-headers operations take place, arrange to
+# copy the current version of the relevant header files locally, generate
+# the alternate version and replace the original version with ours:
+
+stmp-int-hdrs: subst-glimits.h
+
+subst-%.h:
+	cp -p $(srcdir)/$*.h orig-$*.h
+	ID=$$(echo $(BASEVER_c) | sed -e 's/\./_/g'); \
+	sed -e "s/_LIMITS_H__/_LIMITS_H_$${ID}_/" < $(srcdir)/$*.h > $@
+	cp $@ $(srcdir)/$*.h
+
+# Then arrange to restore the original versions after the standard
+# operations have taken place:
+
+INSTALL_HEADERS += restore-glimits.h
+
+restore-glimits.h: stmp-int-hdrs
+	cp -p orig-glimits.h $(srcdir)/glimits.h