diff --git a/cmake/archdetect.cmake b/cmake/archdetect.cmake
new file mode 100644
index 00000000..3ffcb282
--- /dev/null
+++ b/cmake/archdetect.cmake
@@ -0,0 +1,75 @@
+if (USE_CPU_NATIVE)
+    # Detect best GNUCC_ARCH to tune for
+    if (CMAKE_COMPILER_IS_GNUCC)
+        message(STATUS "gcc version ${CMAKE_C_COMPILER_VERSION}")
+
+        # If gcc doesn't recognise the host cpu, then mtune=native becomes
+        # generic, which isn't very good in some cases. march=native looks at
+        # cpuid info and then chooses the best microarch it can (and replaces
+        # the flag), so use that for tune.
+
+        set(TUNE_FLAG "mtune")
+        set(GNUCC_TUNE "")
+        message(STATUS "ARCH_FLAG '${ARCH_FLAG}' '${GNUCC_ARCH}', TUNE_FLAG '${TUNE_FLAG}' '${GNUCC_TUNE}' ")
+
+        # arg1 might exist if using ccache
+        string (STRIP "${CMAKE_C_COMPILER_ARG1}" CC_ARG1)
+        set (EXEC_ARGS ${CC_ARG1} -c -Q --help=target -${ARCH_FLAG}=native -${TUNE_FLAG}=native)
+        execute_process(COMMAND ${CMAKE_C_COMPILER} ${EXEC_ARGS}
+            OUTPUT_VARIABLE _GCC_OUTPUT)
+        set(_GCC_OUTPUT_TUNE ${_GCC_OUTPUT})
+        string(FIND "${_GCC_OUTPUT}" "${ARCH_FLAG}=" POS)
+        string(SUBSTRING "${_GCC_OUTPUT}" ${POS} -1 _GCC_OUTPUT)
+        string(REGEX REPLACE "${ARCH_FLAG}=[ \t]*([^ \n]*)[ \n].*" "\\1" GNUCC_ARCH "${_GCC_OUTPUT}")
+
+        string(FIND "${_GCC_OUTPUT_TUNE}" "${TUNE_FLAG}=" POS_TUNE)
+        string(SUBSTRING "${_GCC_OUTPUT_TUNE}" ${POS_TUNE} -1 _GCC_OUTPUT_TUNE)
+        string(REGEX REPLACE "${TUNE_FLAG}=[ \t]*([^ \n]*)[ \n].*" "\\1" GNUCC_TUNE "${_GCC_OUTPUT_TUNE}")
+
+        message(STATUS "ARCH_FLAG '${ARCH_FLAG}' '${GNUCC_ARCH}', TUNE_FLAG '${TUNE_FLAG}' '${GNUCC_TUNE}' ")
+
+        # test the parsed flag
+        set (EXEC_ARGS ${CC_ARG1} -E - -${ARCH_FLAG}=${GNUCC_ARCH} -${TUNE_FLAG}=${GNUCC_TUNE})
+        execute_process(COMMAND ${CMAKE_C_COMPILER} ${EXEC_ARGS}
+            OUTPUT_QUIET ERROR_QUIET
+            INPUT_FILE /dev/null
+            RESULT_VARIABLE GNUCC_TUNE_TEST)
+
+        if (NOT GNUCC_TUNE_TEST EQUAL 0)
+            message(WARNING "Something went wrong determining gcc tune: -mtune=${GNUCC_TUNE} not valid, falling back to -mtune=native")
+            set(GNUCC_TUNE native)
+        else()
+            set(GNUCC_TUNE ${GNUCC_TUNE})
+            message(STATUS "gcc will tune for ${GNUCC_ARCH}, ${GNUCC_TUNE}")
+        endif()
+    elseif (CMAKE_COMPILER_IS_CLANG)
+        if (ARCH_IA32 OR ARCH_X86_64)
+            set(GNUCC_ARCH native)
+            set(TUNE_FLAG generic)
+        elseif(ARCH_AARCH64)
+            set(GNUCC_ARCH armv8)
+            set(TUNE_FLAG generic)
+        elseif(ARCH_ARM32)
+            set(GNUCC_ARCH armv7a)
+            set(TUNE_FLAG generic)
+        else()
+            set(GNUCC_ARCH native)
+            set(TUNE_FLAG generic)
+        endif()
+        message(STATUS "clang will tune for ${GNUCC_ARCH}, ${TUNE_FLAG}")
+    endif()
+else()
+    if (ARCH_IA32 OR ARCH_X86_64)
+        set(GNUCC_ARCH generic)
+        set(TUNE_FLAG generic)
+    elseif(ARCH_AARCH64)
+       set(GNUCC_ARCH armv8-a)
+       set(TUNE_FLAG generic)
+    elseif(ARCH_ARM32)
+       set(GNUCC_ARCH armv7a)
+       set(TUNE_FLAG generic)
+    else()
+       set(GNUCC_ARCH generic)
+       set(TUNE_FLAG generic)
+    endif()
+endif()