diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6166215f5f4..5d3c8d42401 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2019-07-10  Iain Sandoe  <iain@sandoe.co.uk>
+
+	* config/rs6000/darwin.h (LIB_SPEC): Collate this spec here.
+	* config/rs6000/darwin7.h (LIB_SPEC): Remove.
+	* config/rs6000/darwin8.h (LIB_SPEC): Remove.
+	(DEF_MIN_OSX_VERSION): New.
+
 2019-07-10  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* fold-const.c (fold_relational_const): Fix folding of
diff --git a/gcc/config/rs6000/darwin.h b/gcc/config/rs6000/darwin.h
index b0b50476970..272cd454189 100644
--- a/gcc/config/rs6000/darwin.h
+++ b/gcc/config/rs6000/darwin.h
@@ -86,6 +86,24 @@ extern int darwin_emit_picsym_stub;
 
 #define RS6000_DEFAULT_LONG_DOUBLE_SIZE 128
 
+/* Machine dependent libraries.
+   Include libmx when targeting Darwin 7.0 and above, but before libSystem,
+   since the functions are actually in libSystem but for 7.x compatibility
+   we want them to be looked for in libmx first.
+   Include libSystemStubs when compiling against 10.3 - 10.5 SDKs (we assume
+   this is the case when targetting these) - but not for 64-bit long double.
+   Don't do either for m64, the library is either a dummy or non-existent.
+*/
+
+#undef LIB_SPEC
+#define LIB_SPEC \
+"%{!static:								\
+  %{!m64:%{!mlong-double-64:						\
+    %{pg:%:version-compare(>< 10.3 10.5 mmacosx-version-min= -lSystemStubs_profile)} \
+    %{!pg:%:version-compare(>< 10.3 10.5 mmacosx-version-min= -lSystemStubs)} \
+     %:version-compare(>< 10.3 10.4 mmacosx-version-min= -lmx)}}	\
+  -lSystem								\
+}"
 
 /* We want -fPIC by default, unless we're using -static to compile for
    the kernel or some such.  The "-faltivec" option should have been
diff --git a/gcc/config/rs6000/darwin7.h b/gcc/config/rs6000/darwin7.h
index d299074eacc..6a3adc0297c 100644
--- a/gcc/config/rs6000/darwin7.h
+++ b/gcc/config/rs6000/darwin7.h
@@ -17,21 +17,11 @@ You should have received a copy of the GNU General Public License
 along with GCC; see the file COPYING3.  If not see
 <http://www.gnu.org/licenses/>.  */
 
-/* Machine dependent libraries.  Include libmx when compiling for
-   Darwin 7.0 and above, but before libSystem, since the functions are
-   actually in libSystem but for 7.x compatibility we want them to be
-   looked for in libmx first.  Include libmx by default because otherwise
-   libstdc++ isn't usable.  */
-
-#undef	LIB_SPEC
-#define LIB_SPEC "%{!static:\
-  %:version-compare(!< 10.3 mmacosx-version-min= -lmx)\
-  -lSystem}"
-
 /* This generation of tools (specifically the archive tool) did not
    export weak symbols from the TOC. */
 #undef TARGET_WEAK_NOT_IN_ARCHIVE_TOC
 #define TARGET_WEAK_NOT_IN_ARCHIVE_TOC 1
 
+/* Default to the last version, with most support for C++.  */
 #undef DEF_MIN_OSX_VERSION
 #define DEF_MIN_OSX_VERSION "10.3.9"
diff --git a/gcc/config/rs6000/darwin8.h b/gcc/config/rs6000/darwin8.h
index ca4ede21046..ec5a8af37cd 100644
--- a/gcc/config/rs6000/darwin8.h
+++ b/gcc/config/rs6000/darwin8.h
@@ -17,15 +17,5 @@ You should have received a copy of the GNU General Public License
 along with GCC; see the file COPYING3.  If not see
 <http://www.gnu.org/licenses/>.  */
 
-/* Machine dependent libraries.  Include libmx when compiling on
-   Darwin 7.0 and above, but before libSystem, since the functions are
-   actually in libSystem but for 7.x compatibility we want them to be
-   looked for in libmx first---but only do this if 7.x compatibility
-   is a concern, which it's not in 64-bit mode.  Include
-   libSystemStubs when compiling on (not necessarily for) 8.0 and
-   above and not 64-bit long double.  */
-
-#undef	LIB_SPEC
-#define LIB_SPEC "%{!static:\
-  %{!mlong-double-64:%{pg:-lSystemStubs_profile;:-lSystemStubs}} \
-  %{!m64:%:version-compare(>< 10.3 10.4 mmacosx-version-min= -lmx)} -lSystem}"
+#undef DEF_MIN_OSX_VERSION
+#define DEF_MIN_OSX_VERSION "10.4"