diff -r 13588c901957 -r 9cf78a70fa4f make/autoconf/hotspot.m4
--- a/make/autoconf/hotspot.m4	Thu Oct 17 20:27:44 2019 +0100
+++ b/make/autoconf/hotspot.m4	Thu Oct 17 20:53:35 2019 +0100
@@ -341,7 +341,7 @@
 
   # Only enable Shenandoah on supported arches
   AC_MSG_CHECKING([if shenandoah can be built])
-  if test "x$OPENJDK_TARGET_CPU" = "xx86_64" || test "x$OPENJDK_TARGET_CPU" = "xaarch64" ; then
+  if test "x$OPENJDK_TARGET_CPU_ARCH" = "xx86" || test "x$OPENJDK_TARGET_CPU" = "xaarch64" ; then
     AC_MSG_RESULT([yes])
   else
     DISABLED_JVM_FEATURES="$DISABLED_JVM_FEATURES shenandoahgc"
@@ -350,7 +350,8 @@
 
   # Only enable ZGC on supported platforms
   AC_MSG_CHECKING([if zgc can be built])
-  if test "x$OPENJDK_TARGET_OS" = "xlinux" && test "x$OPENJDK_TARGET_CPU" = "xx86_64"; then
+  if (test "x$OPENJDK_TARGET_OS" = "xlinux" && test "x$OPENJDK_TARGET_CPU" = "xx86_64") || \
+     (test "x$OPENJDK_TARGET_OS" = "xlinux" && test "x$OPENJDK_TARGET_CPU" = "xaarch64"); then
     AC_MSG_RESULT([yes])
   else
     DISABLED_JVM_FEATURES="$DISABLED_JVM_FEATURES zgc"