diff --git a/closed/OpenJ9.gmk b/closed/OpenJ9.gmk
index 26eea35d3e2..69d11f7cef9 100644
--- a/closed/OpenJ9.gmk
+++ b/closed/OpenJ9.gmk
@@ -338,6 +338,7 @@ ifeq (true,$(OPENJ9_ENABLE_CMAKE))
 	-DJ9VM_OMR_DIR="$(OPENJ9OMR_TOPDIR)" \
 	-DJAVA_SPEC_VERSION=$(VERSION_FEATURE) \
 	-DOMR_DDR=$(OPENJ9_ENABLE_DDR) \
+	-DOMR_MIXED_REFERENCES_MODE=$(OMR_MIXED_REFERENCES_MODE) \
 	-DOPENJ9_BUILD=true \
 	-DOPENJ9_SHA=$(OPENJ9_SHA) \
 	-DOPENJDK_VERSION_NUMBER_FOUR_POSITIONS=$(VERSION_NUMBER_FOUR_POSITIONS) \
diff --git a/closed/autoconf/custom-hook.m4 b/closed/autoconf/custom-hook.m4
index c086310afc1..5f7845dab75 100644
--- a/closed/autoconf/custom-hook.m4
+++ b/closed/autoconf/custom-hook.m4
@@ -54,7 +54,7 @@ AC_DEFUN([OPENJ9_CONFIGURE_CMAKE],
 [
   AC_ARG_WITH(cmake, [AS_HELP_STRING([--with-cmake], [enable building openJ9 with CMake])],
     [
-      if test "x$with_cmake" == xyes -o "x$with_cmake" == x ; then
+      if test "x$with_cmake" = xyes -o "x$with_cmake" = x ; then
         with_cmake=cmake
       fi
     ],
@@ -75,6 +75,11 @@ AC_DEFUN([OPENJ9_CONFIGURE_CMAKE],
   # at this point with_cmake should either be no, or the name of the cmake command
   if test "x$with_cmake" = xno ; then
     OPENJ9_ENABLE_CMAKE=false
+
+    # Currently, mixedrefs mode is only available with CMake enabled
+    if test "x$OMR_MIXED_REFERENCES_MODE" != xoff ; then
+      AC_MSG_ERROR([[--with-mixedrefs=[static|dynamic] requires --with-cmake]])
+    fi
   else
     OPENJ9_ENABLE_CMAKE=true
     if AS_EXECUTABLE_P(["$with_cmake"]) ; then
@@ -342,43 +347,56 @@ AC_DEFUN([OPENJ9_PLATFORM_SETUP],
   AC_ARG_WITH(noncompressedrefs, [AS_HELP_STRING([--with-noncompressedrefs],
     [build non-compressedrefs vm (large heap)])])
 
+  AC_ARG_WITH(mixedrefs, [AS_HELP_STRING([--with-mixedrefs],
+    [build mixedrefs vm (--with-mixedrefs=static or --with-mixedrefs=dynamic)])])
+
   # When compiling natively host_cpu and build_cpu are the same. But when
   # cross compiling we need to work with the host_cpu (which is where the final
   # JVM will run).
   OPENJ9_PLATFORM_EXTRACT_VARS_FROM_CPU($host_cpu)
 
-  if test "x$with_noncompressedrefs" = x ; then
-    OPENJ9_BUILDSPEC="${OPENJDK_BUILD_OS}_${OPENJ9_CPU}_cmprssptrs"
-    OPENJ9_LIBS_SUBDIR=compressedrefs
-  else
-    OPENJ9_BUILDSPEC="${OPENJDK_BUILD_OS}_${OPENJ9_CPU}"
+  # Default OPENJ9_BUILD_OS=OPENJDK_BUILD_OS, but override with OpenJ9 equivalent as appropriate
+  OPENJ9_BUILD_OS="${OPENJDK_BUILD_OS}"
+
+  OMR_MIXED_REFERENCES_MODE=off
+  if test "x$with_mixedrefs" != x -a "x$with_mixedrefs" != xno; then
+    if test "x$with_mixedrefs" = xyes -o "x$with_mixedrefs" = xstatic; then
+      OMR_MIXED_REFERENCES_MODE=static
+    elif test "x$with_mixedrefs" = xdynamic; then
+      OMR_MIXED_REFERENCES_MODE=dynamic
+    else
+      AC_MSG_ERROR([OpenJ9 supports --with-mixedrefs=static and --with-mixedrefs=dynamic])
+    fi
+    OPENJ9_BUILD_MODE_ARCH="${OPENJ9_CPU}_mxdptrs"
+    OPENJ9_LIBS_SUBDIR=default
+  elif test "x$with_noncompressedrefs" = xyes ; then
+    OPENJ9_BUILD_MODE_ARCH="${OPENJ9_CPU}"
     OPENJ9_LIBS_SUBDIR=default
+  else
+    OPENJ9_BUILD_MODE_ARCH="${OPENJ9_CPU}_cmprssptrs"
+    OPENJ9_LIBS_SUBDIR=compressedrefs
   fi
 
   if test "x$OPENJ9_CPU" = xx86-64 ; then
-    if test "x$OPENJDK_BUILD_OS" = xlinux ; then
+    if test "x$OPENJ9_BUILD_OS" = xlinux ; then
       OPENJ9_PLATFORM_CODE=xa64
-    elif test "x$OPENJDK_BUILD_OS" = xwindows ; then
+    elif test "x$OPENJ9_BUILD_OS" = xwindows ; then
       OPENJ9_PLATFORM_CODE=wa64
-      if test "x$OPENJ9_LIBS_SUBDIR" = xdefault ; then
-        OPENJ9_BUILDSPEC=win_x86-64
-      else
-        OPENJ9_BUILDSPEC=win_x86-64_cmprssptrs
-      fi
-    elif test "x$OPENJDK_BUILD_OS" = xmacosx ; then
+      OPENJ9_BUILD_OS=win
+    elif test "x$OPENJ9_BUILD_OS" = xmacosx ; then
       OPENJ9_PLATFORM_CODE=oa64
-      if test "x$OPENJ9_LIBS_SUBDIR" = xdefault ; then
-        OPENJ9_BUILDSPEC=osx_x86-64
-      else
-        OPENJ9_BUILDSPEC=osx_x86-64_cmprssptrs
-      fi
+      OPENJ9_BUILD_OS=osx
     else
-      AC_MSG_ERROR([Unsupported OpenJ9 platform ${OPENJDK_BUILD_OS}!])
+      AC_MSG_ERROR([Unsupported OpenJ9 platform ${OPENJ9_BUILD_OS}!])
     fi
   elif test "x$OPENJ9_CPU" = xppc-64_le ; then
     OPENJ9_PLATFORM_CODE=xl64
-    if test "x$OPENJ9_LIBS_SUBDIR" != xdefault ; then
-      OPENJ9_BUILDSPEC="${OPENJDK_BUILD_OS}_ppc-64_cmprssptrs_le"
+    if test "x$OMR_MIXED_REFERENCES_MODE" = xoff ; then
+      if test "x$OPENJ9_LIBS_SUBDIR" != xdefault ; then
+        OPENJ9_BUILD_MODE_ARCH="ppc-64_cmprssptrs_le"
+      fi
+    else
+      OPENJ9_BUILD_MODE_ARCH="ppc-64_mxdptrs_le"
     fi
   elif test "x$OPENJ9_CPU" = x390-64 ; then
     OPENJ9_PLATFORM_CODE=xz64
@@ -386,26 +404,30 @@ AC_DEFUN([OPENJ9_PLATFORM_SETUP],
     OPENJ9_PLATFORM_CODE=ap64
   elif test "x$OPENJ9_CPU" = xarm ; then
     OPENJ9_PLATFORM_CODE=xr32
-    OPENJ9_BUILDSPEC=linux_arm_linaro
+    OPENJ9_BUILD_OS=linux
+    OPENJ9_BUILD_MODE_ARCH=arm_linaro
     OPENJ9_LIBS_SUBDIR=default
   elif test "x$OPENJ9_CPU" = xaarch64 ; then
     OPENJ9_PLATFORM_CODE=xr64
     if test "x$COMPILE_TYPE" = xcross ; then
-      OPENJ9_BUILDSPEC="${OPENJ9_BUILDSPEC}_cross"
+      OPENJ9_BUILD_MODE_ARCH="${OPENJ9_BUILD_MODE_ARCH}_cross"
     fi
   elif test "x$OPENJ9_CPU" = xriscv64 ; then
     OPENJ9_PLATFORM_CODE=rv64
     if test "x$COMPILE_TYPE" = xcross ; then
-      OPENJ9_BUILDSPEC="${OPENJ9_BUILDSPEC}_cross"
+      OPENJ9_BUILD_MODE_ARCH="${OPENJ9_BUILD_MODE_ARCH}_cross"
     fi
   else
     AC_MSG_ERROR([Unsupported OpenJ9 cpu ${OPENJ9_CPU}!])
   fi
 
+  OPENJ9_BUILDSPEC="${OPENJ9_BUILD_OS}_${OPENJ9_BUILD_MODE_ARCH}"
+
   AC_SUBST(OPENJ9_BUILDSPEC)
   AC_SUBST(OPENJ9_PLATFORM_CODE)
   AC_SUBST(COMPILER_VERSION_STRING)
   AC_SUBST(OPENJ9_LIBS_SUBDIR)
+  AC_SUBST(OMR_MIXED_REFERENCES_MODE)
 ])
 
 AC_DEFUN([OPENJ9_CHECK_NASM_VERSION],
@@ -452,7 +474,7 @@ AC_DEFUN([OPENJ9_THIRD_PARTY_REQUIREMENTS],
   FREEMARKER_JAR=
   if test "x$OPENJ9_ENABLE_CMAKE" != xtrue ; then
     AC_MSG_CHECKING([that freemarker location is set])
-    if test "x$with_freemarker_jar" == x -o "x$with_freemarker_jar" == xno ; then
+    if test "x$with_freemarker_jar" = x -o "x$with_freemarker_jar" = xno ; then
       AC_MSG_RESULT([no])
       printf "\n"
       printf "The FreeMarker library is required to build the OpenJ9 build tools\n"
diff --git a/closed/autoconf/custom-spec.gmk.in b/closed/autoconf/custom-spec.gmk.in
index be9d524a4eb..3047edaf090 100644
--- a/closed/autoconf/custom-spec.gmk.in
+++ b/closed/autoconf/custom-spec.gmk.in
@@ -85,6 +85,9 @@ OPENJ9_PLATFORM_CODE    := @OPENJ9_PLATFORM_CODE@
 
 OPENJ9_LIBS_SUBDIR      := @OPENJ9_LIBS_SUBDIR@
 
+# Mixed References Mode
+OMR_MIXED_REFERENCES_MODE := @OMR_MIXED_REFERENCES_MODE@
+
 # Export autoconf cache variables for CC/CXX.
 # This is for the case where ccache is enabled.
 # It ensures that OMR autoconf uses the compiler, not ccache.
diff --git a/closed/custom/copy/Copy-java.base.gmk b/closed/custom/copy/Copy-java.base.gmk
index b0f6e2772a3..a2383c30b8f 100644
--- a/closed/custom/copy/Copy-java.base.gmk
+++ b/closed/custom/copy/Copy-java.base.gmk
@@ -63,7 +63,9 @@ $(call openj9_copy_shlibs, \
 	$(if $(filter zos,$(OPENJDK_TARGET_OS)),j9a2e) \
 	j9dmp29 \
 	j9gc29 \
+	$(if $(filter static,$(OMR_MIXED_REFERENCES_MODE)),j9gc_full29) \
 	j9gcchk29 \
+	$(if $(filter static,$(OMR_MIXED_REFERENCES_MODE)),j9gcchk_full29) \
 	j9hookable29 \
 	$(if $(filter zos,$(OPENJDK_TARGET_OS)),j9ifa29) \
 	$(if $(filter $(NO_JIT_CPUS),$(OPENJDK_TARGET_CPU)),,j9jit29) \