diff --git a/racket/src/ChezScheme/c/Mf-arm64osx b/racket/src/ChezScheme/c/Mf-arm64osx
new file mode 100644
index 0000000000..d73163a0b3
--- /dev/null
+++ b/racket/src/ChezScheme/c/Mf-arm64osx
@@ -0,0 +1,45 @@
+# Mf-a6osx
+# Copyright 1984-2017 Cisco Systems, Inc.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# 
+# http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+m ?= arm64osx
+Cpu ?= AARCH64
+
+mdinclude = -I/opt/X11/include/ 
+o = o
+mdsrc ?= arm32le.c
+mdobj ?= arm32le.o
+
+.SUFFIXES:
+.SUFFIXES: .c .o
+
+.c.o:
+	$C -c -D${Cpu} -I${Include} ${zlibInc} ${LZ4Inc} ${mdinclude} $*.c
+
+include Mf-base
+
+${KernelO}: ${kernelobj} ${zlibDep} ${LZ4Dep}
+	${LD} -r -o ${KernelO} ${kernelobj} ${zlibLib} ${LZ4Lib}
+
+${KernelLib}: ${kernelobj}
+	${AR} ${ARFLAGS} ${KernelLib} ${kernelobj}
+
+${Scheme}: ${Kernel} ${KernelLinkDeps} ${Main}
+	$C -o ${Scheme} ${Main} ${Kernel} ${KernelLinkLibs} ${LDFLAGS} ${LIBS}
+
+../zlib/configure.log:
+	(cd ../zlib; ${SetConfigEnv} CFLAGS="${CFLAGS}" ./configure)
+
+../lz4/lib/liblz4.a: ${LZ4Sources}
+	(cd ../lz4/lib; ${SetConfigEnv} CFLAGS="${CFLAGS}" ${MAKE} liblz4.a)
diff --git a/racket/src/ChezScheme/c/Mf-tarm64osx b/racket/src/ChezScheme/c/Mf-tarm64osx
new file mode 100644
index 0000000000..e4d05eb21f
--- /dev/null
+++ b/racket/src/ChezScheme/c/Mf-tarm64osx
@@ -0,0 +1,5 @@
+# Mf-tarm64osx
+
+m ?= tarm64osx
+
+include Mf-arm64osx
diff --git a/racket/src/ChezScheme/c/arm32le.c b/racket/src/ChezScheme/c/arm32le.c
index f2cd6aec3f..085ef0be5b 100644
--- a/racket/src/ChezScheme/c/arm32le.c
+++ b/racket/src/ChezScheme/c/arm32le.c
@@ -41,11 +41,17 @@ void S_doflush(uptr start, uptr end) {
 void S_machine_init() {
   int l1_dcache_line_size, l1_icache_line_size;
 
+#if defined(__linux__)
   if ((l1_dcache_line_size = sysconf(_SC_LEVEL1_DCACHE_LINESIZE)) <= 0) {
     l1_dcache_line_size = DEFAULT_L1_MAX_CACHE_LINE_SIZE;
   }
   if ((l1_icache_line_size = sysconf(_SC_LEVEL1_ICACHE_LINESIZE)) <= 0) {
     l1_icache_line_size = DEFAULT_L1_MAX_CACHE_LINE_SIZE;
   }
+#else
+  l1_dcache_line_size = DEFAULT_L1_MAX_CACHE_LINE_SIZE;
+  l1_icache_line_size = DEFAULT_L1_MAX_CACHE_LINE_SIZE;
+#endif
+
   l1_max_cache_line_size = l1_dcache_line_size > l1_icache_line_size ? l1_dcache_line_size : l1_icache_line_size;
 }
diff --git a/racket/src/ChezScheme/c/atomic.h b/racket/src/ChezScheme/c/atomic.h
index 54db9f44de..854de274b5 100644
--- a/racket/src/ChezScheme/c/atomic.h
+++ b/racket/src/ChezScheme/c/atomic.h
@@ -37,38 +37,38 @@
 # define CAS_ANY_FENCE(a, old, new) ((*(a) == (old)) ? (*(a) = (new), 1) : 0)
 #elif defined(__arm64__)
 FORCEINLINE int CAS_LOAD_ACQUIRE(volatile void *addr, void *old_val, void *new_val) {
-  int ret;
+  long ret;
   __asm__ __volatile__ ("mov %0, #0\n\t"       
                         "0:\n\t"
-                        "ldaxr r12, [%1, #0]\n\t"
-                        "cmp r12, %2\n\t"
+                        "ldaxr x12, [%1, #0]\n\t"
+                        "cmp x12, %2\n\t"
                         "bne 1f\n\t"
-                        "stxr r7, %3, [%1, #0]\n\t"
-                        "cmp r7, #0\n\t"
+                        "stxr x7, %3, [%1, #0]\n\t"
+                        "cmp x7, #0\n\t"
                         "bne 1f\n\t"
                         "moveq %0, #1\n\t"
                         "1:\n\t"
                         : "=&r" (ret)
                         : "r" (addr), "r" (old_val), "r" (new_val)
-                        : "cc", "memory", "r12", "r7");
+                        : "cc", "memory", "x12", "x7");
   return ret;
 }
 /* same as above, but ldaxr -> ldxr and stxr -> stlxr */
 FORCEINLINE int CAS_STORE_RELEASE(volatile void *addr, void *old_val, void *new_val) {
-  int ret;
+  long ret;
   __asm__ __volatile__ ("mov %0, #0\n\t"       
                         "0:\n\t"
-                        "ldxr r12, [%1, #0]\n\t"
-                        "cmp r12, %2\n\t"
+                        "ldxr x12, [%1, #0]\n\t"
+                        "cmp x12, %2\n\t"
                         "bne 1f\n\t"
-                        "stlxr r7, %3, [%1, #0]\n\t"
-                        "cmp r7, #0\n\t"
+                        "stlxr x7, %3, [%1, #0]\n\t"
+                        "cmp x7, #0\n\t"
                         "bne 1f\n\t"
                         "moveq %0, #1\n\t"
                         "1:\n\t"
                         : "=&r" (ret)
                         : "r" (addr), "r" (old_val), "r" (new_val)
-                        : "cc", "memory", "r12", "r7");
+                        : "cc", "memory", "x12", "x7");
   return ret;
 }
 #elif defined(__arm__)
diff --git a/racket/src/ChezScheme/c/version.h b/racket/src/ChezScheme/c/version.h
index 199e6d8de6..e8cd18f54e 100644
--- a/racket/src/ChezScheme/c/version.h
+++ b/racket/src/ChezScheme/c/version.h
@@ -78,6 +78,13 @@
 # endif
 #endif
 
+#if (machine_type == machine_type_arm64osx || machine_type == machine_type_tarm64osx)
+# define OS_ANY_MACOSX
+# if (machine_type == machine_type_tarm64osx)
+#  define PTHREADS
+# endif
+#endif
+
 #if (machine_type == machine_type_pb)
 # if defined(__powerpc__) && !defined(__powerpc64__)
 #  define PORTABLE_BYTECODE_BIGENDIAN
diff --git a/racket/src/ChezScheme/configure b/racket/src/ChezScheme/configure
index 98e0a75476..1ff39ad7d6 100755
--- a/racket/src/ChezScheme/configure
+++ b/racket/src/ChezScheme/configure
@@ -156,6 +156,9 @@ case "${CONFIG_UNAME}" in
       m64=a6osx
       tm32=ti3osx
       tm64=ta6osx
+    elif uname -a | egrep 'arm|aarch' > /dev/null 2>&1 ; then
+      m64=arm64osx
+      tm64=tarm6osx
     fi
     installprefix=/usr/local
     installmansuffix=share/man
@@ -511,6 +514,9 @@ if [ "$cflagsset" = "no" ] ; then
     a6osx|ta6osx)
         CFLAGS="-m64 ${optFlags}"
         ;;
+    arm64osx|tarm64osx)
+        CFLAGS="-arch arm ${optFlags}"
+        ;;
     a6nt|ta6nt)
         CFLAGS="${optFlags}"
         ;;
diff --git a/racket/src/ChezScheme/s/Mf-arm64le b/racket/src/ChezScheme/s/Mf-arm64le
index 74195ef2ba..1c7ce88365 100644
--- a/racket/src/ChezScheme/s/Mf-arm64le
+++ b/racket/src/ChezScheme/s/Mf-arm64le
@@ -1,4 +1,4 @@
-# Mf-tarm64le
+# Mf-arm64le
 # Copyright 1984-2017 Cisco Systems, Inc.
 # 
 # Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/racket/src/ChezScheme/s/Mf-arm64osx b/racket/src/ChezScheme/s/Mf-arm64osx
new file mode 100644
index 0000000000..92a5257213
--- /dev/null
+++ b/racket/src/ChezScheme/s/Mf-arm64osx
@@ -0,0 +1,21 @@
+# Mf-arm64osx
+# Copyright 1984-2017 Cisco Systems, Inc.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# 
+# http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+m ?= arm64osx
+archincludes = arm64.ss
+
+include Mf-base
+
+machine.def: arm64.def
diff --git a/racket/src/ChezScheme/s/Mf-tarm64osx b/racket/src/ChezScheme/s/Mf-tarm64osx
new file mode 100644
index 0000000000..09f0a2a416
--- /dev/null
+++ b/racket/src/ChezScheme/s/Mf-tarm64osx
@@ -0,0 +1,18 @@
+# Mf-tarm64osx
+# Copyright 1984-2017 Cisco Systems, Inc.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# 
+# http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+m = tarm64osx
+
+include Mf-arm64osx
diff --git a/racket/src/ChezScheme/s/arm64.ss b/racket/src/ChezScheme/s/arm64.ss
index b32e3dfb41..0b1fdd4d2a 100644
--- a/racket/src/ChezScheme/s/arm64.ss
+++ b/racket/src/ChezScheme/s/arm64.ss
@@ -298,8 +298,10 @@
 
   (define-instruction value popcount
     [(op (z ur) (x ur))
-     (let ([u (make-tmp 'u 'fp)])
-       `(set! ,(make-live-info) ,z (asm ,info ,asm-popcount ,x ,u)))])
+     (let ([u (make-tmp 'u)])
+       (seq
+        `(set! ,(make-live-info) ,u (asm ,null-info ,asm-kill))
+        `(set! ,(make-live-info) ,z (asm ,info ,asm-popcount ,x ,u))))])
 
   (define-instruction value (move)
     [(op (z mem) (x ur))
@@ -1254,7 +1256,7 @@
     (lambda (op dest code*)
       (record-case dest
         [(label) (offset l)
-         (safe-assert (uncond-branch-disp? (+ offset 4)))
+         (safe-assert (uncond-branch-disp? offset))
          (emit-code (op dest code*)
            [26 #b000101]
            [0  (fxand (fxsra (fx+ offset 4) 2) (fx- (fxsll 1 26) 1))])]
@@ -1550,9 +1552,10 @@
 
   (define uncond-branch-disp?
     (lambda (x)
-      (and (fixnum? x) 
-           (fx<= (- (expt 2 26)) x (- (expt 2 20) 1))
-           (not (fxlogtest x #b11)))))
+      (let ([x (+ x 4)]) ; because `branch-always-label-op` adds 4
+        (and (fixnum? x) 
+             (fx<= (- (expt 2 27)) x (- (expt 2 27) 1))
+             (not (fxlogtest x #b11))))))
   
   (define asm-size
     (lambda (x)
diff --git a/racket/src/ChezScheme/s/cmacros.ss b/racket/src/ChezScheme/s/cmacros.ss
index 4387ff0b2d..073874ac3f 100644
--- a/racket/src/ChezScheme/s/cmacros.ss
+++ b/racket/src/ChezScheme/s/cmacros.ss
@@ -394,6 +394,7 @@
   ppc32le   tppc32le
   arm64le   tarm64le
   pb
+  arm64osx  tarm64osx
 )
 
 (include "machine.def")
diff --git a/racket/src/ChezScheme/s/mkheader.ss b/racket/src/ChezScheme/s/mkheader.ss
index 5b5e498799..e1e31417e0 100644
--- a/racket/src/ChezScheme/s/mkheader.ss
+++ b/racket/src/ChezScheme/s/mkheader.ss
@@ -823,6 +823,8 @@
 
             (nl)
             (pr "#define LOCKED_INCR(addr, ret) \\~%")
+            (pr "  do {\\~%")
+            (pr "  long _return_;\\~%")
             (pr "  __asm__ __volatile__ (\"mov %0, #0\\n\\t\"\\~%")
             (pr "                        \"0:\\n\\t\"\\~%")
             (pr "                        \"ldxr x12, [%1, #0]\\n\\t\"\\~%")
@@ -834,12 +836,16 @@
             (pr "                        \"bne 1f\\n\\t\"\\~%")
             (pr "                        \"mov %0, #1\\n\\t\"\\~%")
             (pr "                        \"1:\\n\\t\"\\~%")
-            (pr "                        : \"=&r\" (ret)\\~%")
+            (pr "                        : \"=&r\" (_return_)\\~%")
             (pr "                        : \"r\" (addr)\\~%")
-            (pr "                        : \"cc\", \"memory\", \"x12\", \"x7\")~%")
+            (pr "                        : \"cc\", \"memory\", \"x12\", \"x7\");\\~%")
+            (pr "  ret = _return_;\\~%")
+            (pr "  } while (0)~%")
 
             (nl)
             (pr "#define LOCKED_DECR(addr, ret) \\~%")
+            (pr "  do {\\~%")
+            (pr "  long _return_;\\~%")
             (pr "  __asm__ __volatile__ (\"mov %0, #0\\n\\t\"\\~%")
             (pr "                        \"0:\\n\\t\"\\~%")
             (pr "                        \"ldxr x12, [%1, #0]\\n\\t\"\\~%")
@@ -851,9 +857,11 @@
             (pr "                        \"bne 1f\\n\\t\"\\~%")
             (pr "                        \"mov %0, #1\\n\\t\"\\~%")
             (pr "                        \"1:\\n\\t\"\\~%")
-            (pr "                        : \"=&r\" (ret)\\~%")
+            (pr "                        : \"=&r\" (_return_)\\~%")
             (pr "                        : \"r\" (addr)\\~%")
-            (pr "                        : \"cc\", \"memory\", \"x12\", \"x7\")~%")]
+            (pr "                        : \"cc\", \"memory\", \"x12\", \"x7\");\\~%")
+            (pr "  ret = _return_;\\~%")
+            (pr "  } while (0)~%")]
           [(pb)
            (pr "#define INITLOCK(addr) (*((long *) addr) = 0)~%")
            (pr "#define SPINLOCK(addr) (*((long *) addr) = 1)~%")
diff --git a/racket/src/ChezScheme/s/tarm64osx.def b/racket/src/ChezScheme/s/tarm64osx.def
new file mode 100644
index 0000000000..07f98341c5
--- /dev/null
+++ b/racket/src/ChezScheme/s/tarm64osx.def
@@ -0,0 +1,6 @@
+;;; tarm64osx.def
+
+(define-constant machine-type (constant machine-type-tarm64osx))
+(features iconv expeditor pthreads)
+(include "arm64.def")
+(include "default.def")
diff --git a/racket/src/ChezScheme/workarea b/racket/src/ChezScheme/workarea
index 6c7cadb02f..9287c67e86 100755
--- a/racket/src/ChezScheme/workarea
+++ b/racket/src/ChezScheme/workarea
@@ -55,6 +55,7 @@ case "$Mhost" in
   a6s2) ;;
   arm32le) ;;
   arm64le) ;;
+  arm64osx) ;;
   i3fb) ;;
   i3le) ;;
   i3nb) ;;
@@ -73,6 +74,7 @@ case "$Mhost" in
   ta6s2) Muni=a6s2 ;;
   tarm32le) Muni=arm32le ;;
   tarm64le) Muni=arm64le ;;
+  tarm64osx) Muni=arm64osx ;;
   ti3fb) Muni=i3fb ;;
   ti3le) Muni=i3le ;;
   ti3nb) Muni=i3nb ;;
@@ -101,6 +103,7 @@ case "$Muniarch" in
   a6s2) March=a6 ;;
   arm32le) March=arm32 ;;
   arm64le) March=arm64 ;;
+  arm64osx) March=arm64 ;;
   i3fb) March=i3 ;;
   i3le) March=i3 ;;
   i3nb) March=i3 ;;
diff --git a/racket/src/Makefile.in b/racket/src/Makefile.in
index 678de8567c..df77bd2231 100644
--- a/racket/src/Makefile.in
+++ b/racket/src/Makefile.in
@@ -74,6 +74,7 @@ bc-explain-configure:
 
 racketcs:
 	if [ ! -f cs/c/Makefile ]; then $(MAKE) cs-explain-configure; fi
+	$(MAKE) @MAKE_LOCAL_RACKET@
 	$(MAKE) @CS_BOOTSTRAP_HELP@
 	cd cs/c && $(MAKE) @CS_USE_BOOTSTRAP_HELP@
 
@@ -90,13 +91,13 @@ cs-explain-configure:
 no-local-racket:
 	$(NOOP)
 
-local/bc/racket3m:
+@RUN_LOCAL_RACKET@:
 	mkdir -p local
 	$(MAKE) local/Makefile
-	cd local  && $(MAKE)
+	cd local && $(MAKE)
 
 local/Makefile:
-	cd local && `cd ..; cd $(srcdir); pwd`/configure --disable-gracket
+	cd local && `cd ..; cd $(srcdir); pwd`/configure --disable-gracket @CONFIGURE_LOCAL_RACKET@
 
 # Install (common) ----------------------------------------
 
diff --git a/racket/src/README.txt b/racket/src/README.txt
index e6fab793c2..2872fdd4da 100644
--- a/racket/src/README.txt
+++ b/racket/src/README.txt
@@ -353,7 +353,13 @@ Cross-compilation requires at least two flags to `configure`:
    run `configure` again (with no arguments) in a "local" subdirectory
    to create a build for the current platform.
 
-Some less commonly needed `configure` flags for Racket BC:
+An additional flag is needed for building Racket CS, unless the flag
+`--enable-racket=auto` is used:
+
+ * `--enable-scheme=DIR`, where DIR is a path that has a "ChezScheme"
+   directory where Chez Scheme is built for the host system.
+
+Some less commonly needed `configure` flags are for Racket BC:
 
  * `--enable-stackup`, if the target platform`s stack grows up.
 
diff --git a/racket/src/bc/configure b/racket/src/bc/configure
index f2590983b2..2c74ce17be 100755
--- a/racket/src/bc/configure
+++ b/racket/src/bc/configure
@@ -6948,6 +6948,7 @@ fi
 ############## Racket for Racket ################
 
 if test "${enable_racket}" = "auto" ; then
+  # See also "configure-parent.ac"
   enable_racket="`pwd`/../local/bc/racket3m"
 fi
 
diff --git a/racket/src/bc/configure-parent.ac b/racket/src/bc/configure-parent.ac
index ae9611ac5e..7d8e31e716 100644
--- a/racket/src/bc/configure-parent.ac
+++ b/racket/src/bc/configure-parent.ac
@@ -37,6 +37,8 @@ MAKE_LOCAL_RACKET=no-local-racket
 if test "${enable_racket}" = "auto" ; then
   MAKE_LOCAL_RACKET="local/bc/racket3m"
 fi
+RUN_LOCAL_RACKET="local/bc/racket3m"
+CONFIGURE_LOCAL_RACKET=--enable-bc
 
 if test "${enable_cgcdefault}" = "yes" ; then
   MAIN_VARIANT=cgc
@@ -48,6 +50,8 @@ RUN_RACKET="bc/racket${MAIN_VARIANT}"
 
 AC_SUBST(RUN_RACKET)
 AC_SUBST(MAKE_LOCAL_RACKET)
+AC_SUBST(RUN_LOCAL_RACKET)
+AC_SUBST(CONFIGURE_LOCAL_RACKET)
 
 makefiles="Makefile"
 
diff --git a/racket/src/bc/configure.ac b/racket/src/bc/configure.ac
index fa061ef280..9801b7914a 100644
--- a/racket/src/bc/configure.ac
+++ b/racket/src/bc/configure.ac
@@ -1277,6 +1277,7 @@ fi
 ############## Racket for Racket ################
 
 if test "${enable_racket}" = "auto" ; then
+  # See also "configure-parent.ac"
   enable_racket="`pwd`/../local/bc/racket3m"
 fi
 
diff --git a/racket/src/bc/foreign/libffi/configure.host b/racket/src/bc/foreign/libffi/configure.host
index 2b66a819b4..3b8cc9654a 100644
--- a/racket/src/bc/foreign/libffi/configure.host
+++ b/racket/src/bc/foreign/libffi/configure.host
@@ -11,7 +11,7 @@ case "${host}" in
 	MSVC=1
 	;;
 
-  aarch64*-*-*)
+  aarch64*-*-* | arm64*-*-*)
 	TARGET=AARCH64; TARGETDIR=aarch64
 	SOURCES="ffi.c sysv.S"
 	;;
diff --git a/racket/src/bc/gc2/vm_osx.c b/racket/src/bc/gc2/vm_osx.c
index 43eb39f75a..434e86ecac 100644
--- a/racket/src/bc/gc2/vm_osx.c
+++ b/racket/src/bc/gc2/vm_osx.c
@@ -124,23 +124,41 @@ static void unregister_mach_thread() {
 # define ARCH_thread_state_t ppc_thread_state_t
 # define ARCH_THREAD_STATE PPC_THREAD_STATE
 # define ARCH_THREAD_STATE_COUNT PPC_THREAD_STATE_COUNT
-#elif defined(__arm__) || defined(__arm64__)
+#elif defined(__arm__)
 # define ARCH_thread_state_t arm_thread_state_t
 # define ARCH_THREAD_STATE ARM_THREAD_STATE
 # define ARCH_THREAD_STATE_COUNT ARM_THREAD_STATE_COUNT
 #elif defined(__x86_64__)
+# define ARCH_exception_state_t x86_exception_state64_t
+# define ARCH_EXCEPTION_STATE x86_EXCEPTION_STATE64
+# define ARCH_EXCEPTION_STATE_COUNT x86_EXCEPTION_STATE64_COUNT
 # define ARCH_thread_state_t x86_thread_state64_t
 # define ARCH_THREAD_STATE x86_THREAD_STATE64
 # define ARCH_THREAD_STATE_COUNT x86_THREAD_STATE64_COUNT
 # define USE_THREAD_STATE
 # include <mach/thread_status.h>
 # include <mach/exception.h>
+#elif defined(__arm64__)
+# define ARCH_exception_state_t arm_exception_state64_t
+# define ARCH_EXCEPTION_STATE ARM_EXCEPTION_STATE64
+# define ARCH_EXCEPTION_STATE_COUNT ARM_EXCEPTION_STATE64_COUNT
+# define ARCH_thread_state_t arm_thread_state64_t
+# define ARCH_THREAD_STATE ARM_THREAD_STATE64
+# define ARCH_THREAD_STATE_COUNT ARM_THREAD_STATE64_COUNT
+# define ARCH_FAULTVADDR_FIELD THREAD_FLD(far)
+# define USE_THREAD_STATE
+# include <mach/thread_status.h>
+# include <mach/exception.h>
 #else
 # define ARCH_thread_state_t i386_thread_state_t
 # define ARCH_THREAD_STATE i386_THREAD_STATE
 # define ARCH_THREAD_STATE_COUNT i386_THREAD_STATE_COUNT
 #endif
 
+#ifndef ARCH_FAULTVADDR_FIELD
+# define ARCH_FAULTVADDR_FIELD THREAD_FLD(faultvaddr)
+#endif
+
 /* the structure of an exception msg and its reply */
 typedef struct rep_msg {
   mach_msg_header_t head;
@@ -311,11 +329,11 @@ kern_return_t GC_catch_exception_raise(mach_port_t port,
     p = (void*)exception_data[1];
 #else
     /* We have to do it this way for 64-bit mode: */
-    x86_exception_state64_t exc_state;
-    mach_msg_type_number_t exc_state_count = x86_EXCEPTION_STATE64_COUNT;
-    (void)thread_get_state(thread_port, x86_EXCEPTION_STATE64, (natural_t*)&exc_state,
+    ARCH_exception_state_t exc_state;
+    mach_msg_type_number_t exc_state_count = ARCH_EXCEPTION_STATE_COUNT;
+    (void)thread_get_state(thread_port, ARCH_EXCEPTION_STATE, (natural_t*)&exc_state,
                            &exc_state_count);
-    p = (void *)exc_state. THREAD_FLD(faultvaddr);
+    p = (void *)exc_state.ARCH_FAULTVADDR_FIELD;
 #endif
 
 #if defined(MZ_USE_PLACES)
diff --git a/racket/src/cfg-bc b/racket/src/cfg-bc
index 8a8ac6f63e..db0e460cf3 100755
--- a/racket/src/cfg-bc
+++ b/racket/src/cfg-bc
@@ -585,6 +585,8 @@ ac_unique_file="setup-go.rkt"
 enable_option_checking=no
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
+CONFIGURE_LOCAL_RACKET
+RUN_LOCAL_RACKET
 RUN_RACKET
 CS_USE_BOOTSTRAP_HELP
 CS_BOOTSTRAP_HELP
@@ -2325,6 +2327,8 @@ MAKE_LOCAL_RACKET=no-local-racket
 if test "${enable_racket}" = "auto" ; then
   MAKE_LOCAL_RACKET="local/bc/racket3m"
 fi
+RUN_LOCAL_RACKET="local/bc/racket3m"
+CONFIGURE_LOCAL_RACKET=--enable-bc
 
 if test "${enable_cgcdefault}" = "yes" ; then
   MAIN_VARIANT=cgc
@@ -2337,6 +2341,8 @@ RUN_RACKET="bc/racket${MAIN_VARIANT}"
 
 
 
+
+
 makefiles="Makefile"
 
 ac_config_files="$ac_config_files $makefiles"
diff --git a/racket/src/cfg-cs b/racket/src/cfg-cs
index 90335565ba..cd569b1ac1 100755
--- a/racket/src/cfg-cs
+++ b/racket/src/cfg-cs
@@ -585,6 +585,8 @@ ac_unique_file="setup-go.rkt"
 enable_option_checking=no
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
+CONFIGURE_LOCAL_RACKET
+RUN_LOCAL_RACKET
 RUN_RACKET
 CS_USE_BOOTSTRAP_HELP
 CS_BOOTSTRAP_HELP
@@ -2231,6 +2233,12 @@ fi
 
 MAKE_LOCAL_RACKET=no-local-racket
 
+if test "${enable_racket}" = "auto" ; then
+  MAKE_LOCAL_RACKET="local/cs/c/racketcs"
+fi
+RUN_LOCAL_RACKET="local/cs/c/racketcs"
+CONFIGURE_LOCAL_RACKET=--enable-cs
+
 MAIN_MAKE_TARGET=racketcs
 MAIN_VARIANT=3m
 
@@ -2239,6 +2247,8 @@ RUN_RACKET="cs/c/racketcs"
 
 
 
+
+
 makefiles="Makefile"
 
 ac_config_files="$ac_config_files $makefiles"
diff --git a/racket/src/cs/c/Makefile.in b/racket/src/cs/c/Makefile.in
index 38c984af12..5383e795f1 100644
--- a/racket/src/cs/c/Makefile.in
+++ b/racket/src/cs/c/Makefile.in
@@ -8,7 +8,7 @@ SCHEME_DIR = $(srcdir)/../../ChezScheme
 UP_SCHEME_DIR = $(upsrcdir)/../../ChezScheme
 SCHEME_WORKAREA = ChezScheme
 MACH = @MACH@
-CS_HOST_WORKAREA_PREFIX =
+CS_HOST_WORKAREA_PREFIX = @CS_HOST_WORKAREA_PREFIX@
 SCHEME_HOST_WORKAREA = $(CS_HOST_WORKAREA_PREFIX)$(SCHEME_WORKAREA)
 SCHEME_BIN = $(SCHEME_HOST_WORKAREA)/$(MACH)/bin/$(MACH)/scheme
 SCHEME_INC = $(SCHEME_HOST_WORKAREA)/$(MACH)/boot/$(MACH)
diff --git a/racket/src/cs/c/configure b/racket/src/cs/c/configure
index 795ccdaa1f..2d4522a658 100755
--- a/racket/src/cs/c/configure
+++ b/racket/src/cs/c/configure
@@ -627,6 +627,7 @@ INSTALL_LIBS_ENABLE
 INSTALL_SETUP_RACKET_FLAGS
 INSTALL_SETUP_FLAGS
 RUN_RACKET
+CS_HOST_WORKAREA_PREFIX
 CROSS_COMPILE_TARGET_KIND
 COMP_SUBDIR_CONFIGURE_ARGS
 ENABLE_OR_DISABLE_WPO
@@ -1431,8 +1432,8 @@ Optional Features:
   --enable-pkgscope=<s>   set `raco pkg' default: installation, user, or shared
   --enable-docs           build docs on install (enabled by default)
   --enable-usersetup      setup user-specific files on install
-  --enable-racket=<path>  use <path> as Racket to build; or "auto" to create
-  --enable-scheme=<path>  obsolete
+  --enable-racket=<path>  use <path> as Racket for build; or "auto" to create
+  --enable-scheme=<path>  use <path> as host's build directory for cross
   --enable-mach=<mach>    use Chez Scheme machine type <mach>
   --enable-target=<mach>  cross-build for Chez Scheme machine type <mach>
   --enable-natipkg        add "-natipkg" to library subpath
@@ -3199,6 +3200,8 @@ LZ4_LIB_DEP='$(OWN_LZ4_LIB)'
 LZ4_LIB='$(OWN_LZ4_LIB)'
 LZ4_LIB_UNPACK='$(AR) x $(OWN_LZ4_LIB)'
 
+CS_HOST_WORKAREA_PREFIX=
+
 PLT_CS_SLSP_SUFFIX=
 
 enable_pthread_by_default=yes
@@ -4479,12 +4482,12 @@ case "$MACH_HOST_CPU" in
   x86|i*86)
     MACH="${thread_prefix}i3${MACH_OS}"
     ;;
+  aarch64*|arm64*)
+    MACH="${thread_prefix}arm64${MACH_OS}"
+    ;;
   arm*)
     MACH="${thread_prefix}arm32${MACH_OS}"
     ;;
-  aarch64*)
-    MACH="${thread_prefix}arm64${MACH_OS}"
-    ;;
   power*)
     MACH="${thread_prefix}ppc32${MACH_OS}"
     ;;
@@ -4536,12 +4539,12 @@ elif test "${build_os}_${build_cpu}" != "${host_os}_${host_cpu}" ; then
     x86|i*86)
       BUILD_MACH="${BUILD_THREAD_PREFIX}i3${BUILD_OS}"
       ;;
+    aarch64*|arm64*)
+      BUILD_MACH="${BUILD_THREAD_PREFIX}arm64${BUILD_OS}"
+      ;;
     arm*)
       BUILD_MACH="${BUILD_THREAD_PREFIX}arm32${BUILD_OS}"
       ;;
-    aarch64*)
-      BUILD_MACH="${BUILD_THREAD_PREFIX}arm64${BUILD_OS}"
-      ;;
     power*)
       BUILD_MACH="${BUILD_THREAD_PREFIX}ppc32${BUILD_OS}"
       ;;
@@ -4583,10 +4586,15 @@ SCHEME_DIR=${srcdir}/../../ChezScheme
 MAKE_BUILD_SCHEME=checkout
 
 if test "${enable_scheme}" != "" ; then
-  echo Warning: --enable-scheme=... is obsolete and unsupported
+  CS_HOST_WORKAREA_PREFIX="${enable_scheme}/"
 fi
 
 if test "${enable_racket}" != "" ; then
+  if test "${enable_racket}" = "auto" ; then
+    # See also "configure-parent.ac"
+    enable_racket="`pwd`/../../local/cs/c/racketcs"
+    CS_HOST_WORKAREA_PREFIX=../../local/cs/c/
+  fi
   # In non-cross mode, we interpret `--enable-racket` to supply a
   # Racket used only for generating Chez Scheme boot files
   if test "${CROSS_MODE}" = "cross" ; then
@@ -5644,6 +5652,7 @@ SCHEME_CROSS_CONFIG_ARGS="--machine=${TARGET_MACH} --disable-x11 ${cs_auto_flags
 
 
 
+
 
 
 makefiles="Makefile"
diff --git a/racket/src/cs/c/configure-parent.ac b/racket/src/cs/c/configure-parent.ac
index 1ebb357193..53c1cf6403 100644
--- a/racket/src/cs/c/configure-parent.ac
+++ b/racket/src/cs/c/configure-parent.ac
@@ -24,6 +24,12 @@ m4_include(../ac/boothelp.m4)
 
 MAKE_LOCAL_RACKET=no-local-racket
 
+if test "${enable_racket}" = "auto" ; then
+  MAKE_LOCAL_RACKET="local/cs/c/racketcs"
+fi
+RUN_LOCAL_RACKET="local/cs/c/racketcs"
+CONFIGURE_LOCAL_RACKET=--enable-cs
+
 MAIN_MAKE_TARGET=racketcs
 MAIN_VARIANT=3m
 
@@ -31,6 +37,8 @@ RUN_RACKET="cs/c/racketcs"
 
 AC_SUBST(RUN_RACKET)
 AC_SUBST(MAKE_LOCAL_RACKET)
+AC_SUBST(RUN_LOCAL_RACKET)
+AC_SUBST(CONFIGURE_LOCAL_RACKET)
 
 makefiles="Makefile"
 
diff --git a/racket/src/cs/c/configure.ac b/racket/src/cs/c/configure.ac
index f3acaf89ad..502a5c5b4f 100644
--- a/racket/src/cs/c/configure.ac
+++ b/racket/src/cs/c/configure.ac
@@ -20,8 +20,8 @@ AC_ARG_ENABLE(wpo,        [  --enable-wpo            agressively optimize Racket
 AC_ARG_ENABLE(compress,   [  --enable-compress       compress compiled code (enabled by default)])
 AC_ARG_ENABLE(compressboot, [  --enable-compressboot   compress boot files])
 m4_include(../ac/path_arg.m4)
-AC_ARG_ENABLE(racket,     [  --enable-racket=<path>  use <path> as Racket to build; or "auto" to create])
-AC_ARG_ENABLE(scheme,     [  --enable-scheme=<path>  obsolete])
+AC_ARG_ENABLE(racket,     [  --enable-racket=<path>  use <path> as Racket for build; or "auto" to create])
+AC_ARG_ENABLE(scheme,     [  --enable-scheme=<path>  use <path> as host's build directory for cross])
 AC_ARG_ENABLE(mach,       [  --enable-mach=<mach>    use Chez Scheme machine type <mach>])
 AC_ARG_ENABLE(target,     [  --enable-target=<mach>  cross-build for Chez Scheme machine type <mach>])
 m4_include(../ac/natipkg_arg.m4)
@@ -157,6 +157,8 @@ LZ4_LIB_DEP='$(OWN_LZ4_LIB)'
 LZ4_LIB='$(OWN_LZ4_LIB)'
 LZ4_LIB_UNPACK='$(AR) x $(OWN_LZ4_LIB)'
 
+CS_HOST_WORKAREA_PREFIX=
+
 PLT_CS_SLSP_SUFFIX=
 
 enable_pthread_by_default=yes
@@ -346,12 +348,12 @@ case "$MACH_HOST_CPU" in
   x86|i*86)
     MACH="${thread_prefix}i3${MACH_OS}"
     ;;
+  aarch64*|arm64*)
+    MACH="${thread_prefix}arm64${MACH_OS}"
+    ;;
   arm*)
     MACH="${thread_prefix}arm32${MACH_OS}"
     ;;
-  aarch64*)
-    MACH="${thread_prefix}arm64${MACH_OS}"
-    ;;
   power*)
     MACH="${thread_prefix}ppc32${MACH_OS}"
     ;;
@@ -403,12 +405,12 @@ elif test "${build_os}_${build_cpu}" != "${host_os}_${host_cpu}" ; then
     x86|i*86)
       BUILD_MACH="${BUILD_THREAD_PREFIX}i3${BUILD_OS}"
       ;;
+    aarch64*|arm64*)
+      BUILD_MACH="${BUILD_THREAD_PREFIX}arm64${BUILD_OS}"
+      ;;
     arm*)
       BUILD_MACH="${BUILD_THREAD_PREFIX}arm32${BUILD_OS}"
       ;;
-    aarch64*)
-      BUILD_MACH="${BUILD_THREAD_PREFIX}arm64${BUILD_OS}"
-      ;;
     power*)
       BUILD_MACH="${BUILD_THREAD_PREFIX}ppc32${BUILD_OS}"
       ;;
@@ -450,10 +452,15 @@ SCHEME_DIR=${srcdir}/../../ChezScheme
 MAKE_BUILD_SCHEME=checkout
 
 if test "${enable_scheme}" != "" ; then
-  echo Warning: --enable-scheme=... is obsolete and unsupported
+  CS_HOST_WORKAREA_PREFIX="${enable_scheme}/"
 fi
 
 if test "${enable_racket}" != "" ; then
+  if test "${enable_racket}" = "auto" ; then
+    # See also "configure-parent.ac"
+    enable_racket="`pwd`/../../local/cs/c/racketcs"
+    CS_HOST_WORKAREA_PREFIX=../../local/cs/c/
+  fi
   # In non-cross mode, we interpret `--enable-racket` to supply a
   # Racket used only for generating Chez Scheme boot files
   if test "${CROSS_MODE}" = "cross" ; then
@@ -764,6 +771,7 @@ AC_SUBST(CS_COMPILED_SUBDIR)
 AC_SUBST(ENABLE_OR_DISABLE_WPO)
 AC_SUBST(COMP_SUBDIR_CONFIGURE_ARGS)
 AC_SUBST(CROSS_COMPILE_TARGET_KIND)
+AC_SUBST(CS_HOST_WORKAREA_PREFIX)
 AC_SUBST(RUN_RACKET)
 AC_SUBST(INSTALL_SETUP_FLAGS)
 AC_SUBST(INSTALL_SETUP_RACKET_FLAGS)
diff --git a/racket/src/cs/c/embed-boot.rkt b/racket/src/cs/c/embed-boot.rkt
index ed33e1d9c1..5ad55884f9 100644
--- a/racket/src/cs/c/embed-boot.rkt
+++ b/racket/src/cs/c/embed-boot.rkt
@@ -53,7 +53,8 @@
                    bstr3 terminator))
    (define pos
      (case (or target (path->string (system-library-subpath #f)))
-       [("x86_64-darwin" "i386-darwin" "x86_64-macosx" "i386-macosx")
+       [("x86_64-darwin" "i386-darwin" "aarch64-darwin"
+         "x86_64-macosx" "i386-macosx" "aarch64-macosx")
         ;; Mach-O
         (copy-file use-src-file dest-file #t)
         (add-plt-segment dest-file data #:name #"__RKTBOOT")
diff --git a/racket/src/cs/rumble/system.ss b/racket/src/cs/rumble/system.ss
index 11e23778f1..6987ec6b72 100644
--- a/racket/src/cs/rumble/system.ss
+++ b/racket/src/cs/rumble/system.ss
@@ -26,9 +26,12 @@
 
 (define os*-symbol
   (case (machine-type)
-    [(a6osx ta6osx i3osx ti3osx) (if unix-style-macos?
-                                     'darwin
-                                     'macosx)]
+    [(a6osx ta6osx
+            i3osx ti3osx
+            arm64osx tarm64osx)
+     (if unix-style-macos?
+         'darwin
+         'macosx)]
     [(a6nt ta6nt i3nt ti3nt) 'windows]
     [(a6le ta6le i3le ti3le
            arm32le tarm32le arm64le tarm64le