Index: ps/trunk/build/premake/premake5.lua
===================================================================
--- ps/trunk/build/premake/premake5.lua
+++ ps/trunk/build/premake/premake5.lua
@@ -61,7 +61,7 @@
 	end
 end
 
--- detect CPU architecture (simplistic, currently only supports x86, amd64 and ARM)
+-- detect CPU architecture (simplistic)
 arch = "x86"
 macos_arch = "x86_64"
 if _OPTIONS["android"] then
@@ -71,33 +71,33 @@
 		arch = "amd64"
 	end
 else
-	arch = os.getenv("HOSTTYPE")
-	-- Force x86_64 on Mac OS for now, as Spidermonkey 78 isn't Apple Silicon compatible.
+	os.execute(cc .. " -dumpmachine > .gccmachine.tmp")
+	local f = io.open(".gccmachine.tmp", "r")
+	local machine = f:read("*line")
+	f:close()
+	-- Special handling on mac os where xcode needs special flags.
 	if os.istarget("macosx") then
-		arch = "amd64"
-		macos_arch = "x86_64"
-	elseif arch == "x86_64" or arch == "amd64" then
-		arch = "amd64"
-	else
-		os.execute(cc .. " -dumpmachine > .gccmachine.tmp")
-		local f = io.open(".gccmachine.tmp", "r")
-		local machine = f:read("*line")
-		f:close()
-		if string.find(machine, "x86_64") == 1 or string.find(machine, "amd64") == 1 then
-			arch = "amd64"
-		elseif string.find(machine, "i.86") == 1 then
-			arch = "x86"
-		elseif string.find(machine, "arm") == 1 then
-			arch = "arm"
-		elseif string.find(machine, "aarch64") == 1 then
+		if string.find(machine, "arm64") then
 			arch = "aarch64"
-		elseif string.find(machine, "e2k") == 1 then
-			arch = "e2k"
-		elseif string.find(machine, "ppc64") == 1 or string.find(machine, "powerpc64") == 1 then
-			arch = "ppc64"
+			macos_arch = "arm64"
 		else
-			print("WARNING: Cannot determine architecture from GCC, assuming x86")
+			arch = "amd64"
+			macos_arch = "x86_64"
 		end
+	elseif string.find(machine, "x86_64") == 1 or string.find(machine, "amd64") == 1 then
+		arch = "amd64"
+	elseif string.find(machine, "i.86") == 1 then
+		arch = "x86"
+	elseif string.find(machine, "arm") == 1 then
+		arch = "arm"
+	elseif string.find(machine, "aarch64") == 1 then
+		arch = "aarch64"
+	elseif string.find(machine, "e2k") == 1 then
+		arch = "e2k"
+	elseif string.find(machine, "ppc64") == 1 or string.find(machine, "powerpc64") == 1 then
+		arch = "ppc64"
+	else
+		print("WARNING: Cannot determine architecture from GCC, assuming x86")
 	end
 end
 
@@ -327,8 +327,8 @@
 				links { "gcov" }
 			end
 
-			-- MacOS 10.12 only supports processors with SSE 4.1, so enable that.
-			if os.istarget("macosx") then
+			-- MacOS 10.12 only supports intel processors with SSE 4.1, so enable that.
+			if os.istarget("macosx") and arch == "amd64" then
 				buildoptions { "-msse4.1" }
 			end
 
Index: ps/trunk/libraries/osx/build-osx-libs.sh
===================================================================
--- ps/trunk/libraries/osx/build-osx-libs.sh
+++ ps/trunk/libraries/osx/build-osx-libs.sh
@@ -36,14 +36,14 @@
 OGG_VERSION="libogg-1.3.3"
 VORBIS_VERSION="libvorbis-1.3.7"
 # gloox requires GnuTLS, GnuTLS requires Nettle and GMP
-GMP_VERSION="gmp-6.2.0"
+GMP_VERSION="gmp-6.2.1"
 NETTLE_VERSION="nettle-3.6"
 # NOTE: remember to also update LIB_URL below when changing version
 GLOOX_VERSION="gloox-1.0.24"
 GNUTLS_VERSION="gnutls-3.6.15"
 # OS X only includes part of ICU, and only the dylib
 # NOTE: remember to also update LIB_URL below when changing version
-ICU_VERSION="icu4c-67_1"
+ICU_VERSION="icu4c-69_1"
 ENET_VERSION="enet-1.3.17"
 MINIUPNPC_VERSION="miniupnpc-2.2.2"
 SODIUM_VERSION="libsodium-1.0.18"
@@ -61,6 +61,7 @@
 
 export CC=${CC:="clang"} CXX=${CXX:="clang++"}
 export MIN_OSX_VERSION=${MIN_OSX_VERSION:="10.12"}
+export ARCH=${ARCH:=""}
 
 # The various libs offer inconsistent configure options, some allow
 # setting sysroot and OS X-specific options, others don't. Adding to
@@ -83,7 +84,7 @@
 fi
 
 CFLAGS="$CFLAGS $C_FLAGS -fvisibility=hidden"
-CXXFLAGS="$CXXFLAGS $C_FLAGS -stdlib=libc++ -std=c++17 -msse4.1"
+CXXFLAGS="$CXXFLAGS $C_FLAGS -stdlib=libc++ -std=c++17"
 OBJCFLAGS="$OBJCFLAGS $C_FLAGS"
 OBJCXXFLAGS="$OBJCXXFLAGS $C_FLAGS"
 
@@ -94,16 +95,31 @@
 ARCHLESS_CXXFLAGS=$CXXFLAGS
 ARCHLESS_LDFLAGS="$LDFLAGS -stdlib=libc++"
 
-CFLAGS="$CFLAGS -arch x86_64"
-CXXFLAGS="$CXXFLAGS -arch x86_64"
+# If ARCH isn't set, select either x86_64 or arm64
+if [ -z "${ARCH}" ]; then
+  if [ "`uname -m`" == "arm64" ]; then
+    ARCH="arm64"
+    # Some libs want this passed to configure for cross compilation.
+    HOST_PLATFORM="--host=aarch64-apple-darwin"
+  else
+    CXXFLAGS="$CXXFLAGS -msse4.1"
+    ARCH="x86_64"
+    # Some libs want this passed to configure for cross compilation.
+    HOST_PLATFORM="--host=x86_64-apple-darwin"
+  fi
+fi
+
+echo "ARCHITECTURE BREAKDOWN"
+echo $ARCH
+echo $HOST_PLATFORM
 
-LDFLAGS="$LDFLAGS -arch x86_64"
+CFLAGS="$CFLAGS -arch $ARCH"
+CXXFLAGS="$CXXFLAGS -arch $ARCH"
 
-# Some libs want this passed to configure for cross compilation.
-HOST_PLATFORM="--host=x86_64-apple-darwin"
+LDFLAGS="$LDFLAGS -arch $ARCH"
 
 # CMake doesn't seem to pick up on architecture with CFLAGS only
-CMAKE_FLAGS="-DCMAKE_OSX_ARCHITECTURES=x86_64"
+CMAKE_FLAGS="-DCMAKE_OSX_ARCHITECTURES=$ARCH"
 
 JOBS=${JOBS:="-j2"}
 
@@ -830,7 +846,7 @@
 LIB_VERSION="${ICU_VERSION}"
 LIB_ARCHIVE="$LIB_VERSION-src.tgz"
 LIB_DIRECTORY="icu"
-LIB_URL="https://github.com/unicode-org/icu/releases/download/release-67-1/"
+LIB_URL="https://github.com/unicode-org/icu/releases/download/release-69-1/"
 
 mkdir -p icu
 pushd icu > /dev/null
@@ -1039,7 +1055,7 @@
 fi
 
 # Use the regular build script for SM.
-JOBS="$JOBS" ZLIB_DIR="$ZLIB_DIR" ./build.sh || die "Error building spidermonkey"
+JOBS="$JOBS" ZLIB_DIR="$ZLIB_DIR" ARCH="$ARCH" ./build.sh || die "Error building spidermonkey"
 
 popd > /dev/null
 
Index: ps/trunk/libraries/source/nvtt/src/src/nvcore/Debug.cpp
===================================================================
--- ps/trunk/libraries/source/nvtt/src/src/nvcore/Debug.cpp
+++ ps/trunk/libraries/source/nvtt/src/src/nvcore/Debug.cpp
@@ -607,6 +607,9 @@
 #    elif NV_CPU_ARM
         ucontext_t * ucp = (ucontext_t *)secret;
         return (void *) ucp->uc_mcontext->__ss.__pc;
+#    elif NV_CPU_AARCH64
+        ucontext_t * ucp = (ucontext_t *)secret;
+        return (void *) ucp->uc_mcontext->__ss.__pc;
 #    else
 #      error "Unknown CPU"
 #    endif
Index: ps/trunk/libraries/source/spidermonkey/FixMacBuild.diff
===================================================================
--- ps/trunk/libraries/source/spidermonkey/FixMacBuild.diff
+++ ps/trunk/libraries/source/spidermonkey/FixMacBuild.diff
@@ -32,4 +32,65 @@
 -                'https://github.com/phracker/MacOSX-SDKs' % (version, sdk_max_version))
          return sdk
  
-     set_config('MACOS_SDK_DIR', macos_sdk)
\ No newline at end of file
+     set_config('MACOS_SDK_DIR', macos_sdk)
+--- a/build/moz.configure/init.configure
++++ b/build/moz.configure/init.configure
+@@ -375,9 +375,6 @@
+         sys.exit(subprocess.call([python] + sys.argv))
+ 
+     # We are now in the virtualenv
+-    if not distutils.sysconfig.get_python_lib():
+-        die('Could not determine python site packages directory')
+-
+     str_version = '.'.join(str(v) for v in version)
+ 
+     return namespace(
+--- a/js/src/jit/arm64/vixl/MozCpu-vixl.cpp
++++ b/js/src/jit/arm64/vixl/MozCpu-vixl.cpp
+@@ -69,7 +69,7 @@ void CPU::SetUp() {
+ 
+ 
+ uint32_t CPU::GetCacheType() {
+-#if defined(__aarch64__) && !defined(_MSC_VER)
++#if defined(__aarch64__) && (defined(__linux__) || defined(__android__))
+   uint64_t cache_type_register;
+   // Copy the content of the cache type register to a core register.
+   __asm__ __volatile__ ("mrs %[ctr], ctr_el0"  // NOLINT
+--- a/js/src/wasm/WasmSignalHandlers.cpp
++++ b/js/src/wasm/WasmSignalHandlers.cpp
+@@ -226,6 +226,10 @@ using mozilla::DebugOnly;
+ #  define R13_sig(p) ((p)->thread.__sp)
+ #  define R14_sig(p) ((p)->thread.__lr)
+ #  define R15_sig(p) ((p)->thread.__pc)
++#  define EPC_sig(p) ((p)->thread.__pc)
++#  define RFP_sig(p) ((p)->thread.__fp)
++#  define R31_sig(p) ((p)->thread.__sp)
++#  define RLR_sig(p) ((p)->thread.__lr)
+ #else
+ #  error "Don't know how to read/write to the thread state via the mcontext_t."
+ #endif
+@@ -351,6 +355,12 @@ struct macos_arm_context {
+   arm_neon_state_t float_;
+ };
+ #    define CONTEXT macos_arm_context
++#  elif defined(__aarch64__)
++struct macos_aarch64_context {
++  arm_thread_state64_t thread;
++  arm_neon_state64_t float_;
++};
++#    define CONTEXT macos_aarch64_context
+ #  else
+ #    error Unsupported architecture
+ #  endif
+@@ -816,6 +826,11 @@ static bool HandleMachException(const ExceptionRequest& request) {
+   unsigned int float_state_count = ARM_NEON_STATE_COUNT;
+   int thread_state = ARM_THREAD_STATE;
+   int float_state = ARM_NEON_STATE;
++#  elif defined(__aarch64__)
++  unsigned int thread_state_count = ARM_THREAD_STATE64_COUNT;
++  unsigned int float_state_count = ARM_NEON_STATE64_COUNT;
++  int thread_state = ARM_THREAD_STATE64;
++  int float_state = ARM_NEON_STATE64;
+ #  else
+ #    error Unsupported architecture
+ #  endif
Index: ps/trunk/libraries/source/spidermonkey/build.sh
===================================================================
--- ps/trunk/libraries/source/spidermonkey/build.sh
+++ ps/trunk/libraries/source/spidermonkey/build.sh
@@ -49,8 +49,15 @@
 
 if [ "`uname -s`" = "Darwin" ]
 then
-  # Explicitly target x86_64.
-  CONF_OPTS="${CONF_OPTS} --target=x86_64-apple-darwin"
+  ARCH=${ARCH:=""}
+  if [ -z "${ARCH}" ]; then
+    if [ "`uname -m`" == "arm64" ]; then
+      ARCH="aarch64"
+    else
+      ARCH="x86_64"
+    fi
+  fi
+  CONF_OPTS="${CONF_OPTS} --target=$ARCH-apple-darwin"
 
   # Link to custom-built zlib
   export PKG_CONFIG_PATH="=${ZLIB_DIR}:${PKG_CONFIG_PATH}"
Index: ps/trunk/source/graphics/Color.cpp
===================================================================
--- ps/trunk/source/graphics/Color.cpp
+++ ps/trunk/source/graphics/Color.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2021 Wildfire Games.
+/* Copyright (C) 2022 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -83,8 +83,9 @@
 		ConvertRGBColorTo4ub = ConvertRGBColorTo4ubSSE;
 		return;
 	}
-#endif
+#elif defined(ARCH_X86_64)
 	debug_printf("No SSE available. Slow fallback routines will be used.\n");
+#endif
 }
 
 /**
Index: ps/trunk/source/tools/dist/build-osx-executable.sh
===================================================================
--- ps/trunk/source/tools/dist/build-osx-executable.sh
+++ ps/trunk/source/tools/dist/build-osx-executable.sh
@@ -2,8 +2,7 @@
 
 # Build the Pyrogenesis executable, used to create the bundle and run the archiver.
 
-# TODO: is there anything to do for ARM support?
-export ARCH=${ARCH:="x86_64"}
+export ARCH=${ARCH:=$(uname -m)}
 
 # Set mimimum required OS X version, SDK location and tools
 # Old SDKs can be found at https://github.com/phracker/MacOSX-SDKs