diff --git a/tools/cpp/CROSSTOOL b/tools/cpp/CROSSTOOL
index 5a374af..7e6efdb 100644
--- a/tools/cpp/CROSSTOOL
+++ b/tools/cpp/CROSSTOOL
@@ -22,6 +22,11 @@
   toolchain_identifier: "clang_linux_armhf"
 }
 
+default_toolchain {
+  cpu: "cortex-m4f"
+  toolchain_identifier: "cortex-m4f"
+}
+
 toolchain {
   abi_version: "armeabi-v7a"
   abi_libc_version: "armeabi-v7a"
@@ -781,3 +786,223 @@
     linker_flag: "-Wl,--gc-sections"
   }
 }
+
+toolchain {
+  abi_version: "cortex-m4f"
+  abi_libc_version: "cortex-m4f"
+  builtin_sysroot: ""
+  compiler: "gcc"
+  host_system_name: "local"
+  needsPic: false
+  supports_gold_linker: false
+  supports_incremental_linker: false
+  supports_fission: false
+  supports_interface_shared_objects: false
+  supports_normalizing_ar: false
+  supports_start_end_lib: false
+  supports_thin_archives: false
+  target_libc: "cortex-m4f"
+  target_cpu: "cortex-m4f"
+  target_system_name: "cortex-m4f"
+  toolchain_identifier: "cortex-m4f"
+
+  tool_path { name: "ar" path: "/usr/bin/arm-none-eabi-ar" }
+  tool_path { name: "compat-ld" path: "/usr/bin/arm-none-eabi-ld" }
+  tool_path { name: "cpp" path: "/usr/bin/arm-none-eabi-cpp" }
+  tool_path { name: "dwp" path: "/usr/bin/arm-none-eabi-dwp" }
+  tool_path { name: "gcc" path: "/usr/bin/arm-none-eabi-gcc" }
+  tool_path { name: "gcov" path: "/usr/bin/arm-none-eabi-gcov" }
+  # C(++) compiles invoke the compiler (as that is the one knowing where
+  # to find libraries), but we provide LD so other rules can invoke the linker.
+  tool_path { name: "ld" path: "/usr/bin/arm-none-eabi-ld" }
+  tool_path { name: "nm" path: "/usr/bin/arm-none-eabi-nm" }
+  tool_path { name: "objcopy" path: "/usr/bin/arm-none-eabi-objcopy" }
+  objcopy_embed_flag: "-I"
+  objcopy_embed_flag: "binary"
+  tool_path { name: "objdump" path: "/usr/bin/arm-none-eabi-objdump" }
+  tool_path { name: "strip" path: "/usr/bin/arm-none-eabi-strip" }
+  linking_mode_flags { mode: FULLY_STATIC }
+
+  # TODO(bazel-team): In theory, the path here ought to exactly match the path
+  # used by gcc. That works because bazel currently doesn't track files at
+  # absolute locations and has no remote execution, yet. However, this will need
+  # to be fixed, maybe with auto-detection?
+  cxx_builtin_include_directory: '/usr/lib/gcc/arm-none-eabi/4.8/include'
+  cxx_builtin_include_directory: '/usr/lib/gcc/arm-none-eabi/4.8/include-fixed'
+  cxx_builtin_include_directory: '/usr/lib/arm-none-eabi/include'
+  cxx_builtin_include_directory: '/usr/include/newlib',
+
+  feature {
+    name: "dbg"
+    implies: "all_modes"
+    flag_set {
+      action: "preprocess-assemble"
+      action: "c-compile"
+      action: "c++-compile"
+      action: "c++-header-parsing"
+      action: "c++-header-preprocessing"
+      action: "c++-module-compile"
+      flag_group {
+        flag: "-fno-omit-frame-pointer"
+      }
+    }
+  }
+
+  feature {
+    name: "opt"
+    implies: "all_modes"
+  }
+  feature {
+    name: "fastbuild"
+    implies: "all_modes"
+  }
+
+  feature {
+    name: "all_modes"
+    flag_set {
+      action: "preprocess-assemble"
+      action: "assemble"
+      action: "c-compile"
+      flag_group {
+        flag: "--std=gnu99"
+      }
+    }
+    flag_set {
+      action: "c++-compile"
+      action: "c++-header-parsing"
+      action: "c++-header-preprocessing"
+      action: "c++-module-compile"
+      flag_group {
+        flag: "--std=gnu++11"
+        flag: "-fno-exceptions"
+        flag: "-fno-rtti"
+      }
+    }
+  }
+
+  # Anticipated future default.
+  # This makes GCC and Clang do what we want when called through symlinks.
+  unfiltered_cxx_flag: "-no-canonical-prefixes"
+  linker_flag: "-no-canonical-prefixes"
+
+  # Things that the code wants defined.
+  compiler_flag: "-D__STDC_FORMAT_MACROS"
+  compiler_flag: "-D__STDC_CONSTANT_MACROS"
+  compiler_flag: "-D__STDC_LIMIT_MACROS"
+  compiler_flag: "-D__MK64FX512__"
+  compiler_flag: "-DF_CPU=120000000"
+  compiler_flag: "-Wl,--gc-sections"
+
+  # Make C++ compilation deterministic. Use linkstamping instead of these
+  # compiler symbols.
+  unfiltered_cxx_flag: "-Wno-builtin-macro-redefined"
+  unfiltered_cxx_flag: "-D__DATE__=\"redacted\""
+  unfiltered_cxx_flag: "-D__TIMESTAMP__=\"redacted\""
+  unfiltered_cxx_flag: "-D__TIME__=\"redacted\""
+
+  # Security hardening on by default.
+  # Conservative choice; -D_FORTIFY_SOURCE=2 may be unsafe in some cases.
+  # We need to undef it before redefining it as some distributions now have
+  # it enabled by default.
+  compiler_flag: "-fstack-protector"
+  compiler_flag: "-mcpu=cortex-m4"
+  compiler_flag: "-mfpu=fpv4-sp-d16"
+  compiler_flag: "-mthumb"
+  compiler_flag: "-mfloat-abi=hard"
+  compiler_flag: "-fno-strict-aliasing"
+  linker_flag: "-mcpu=cortex-m4"
+  linker_flag: "-mfpu=fpv4-sp-d16"
+  linker_flag: "-mthumb"
+  linker_flag: "-mfloat-abi=hard"
+  linker_flag: "-fno-strict-aliasing"
+  linker_flag: "--specs=nano.specs"
+
+  # Pretty much everything needs this, including parts of the glibc STL...
+  linker_flag: "-lgcc"
+  linker_flag: "-lstdc++"
+  linker_flag: "-lm"
+  linker_flag: "-lc"
+  linker_flag: "-Tmotors/core/mk64fx512.ld"
+
+  compiler_flag: "-fmessage-length=80"
+
+  compiler_flag: "-Wall"
+  compiler_flag: "-Wextra"
+  compiler_flag: "-Wswitch-enum"
+  compiler_flag: "-Wpointer-arith"
+  compiler_flag: "-Wcast-qual"
+  compiler_flag: "-Wwrite-strings"
+  compiler_flag: "-Wtype-limits"
+  compiler_flag: "-Wsign-compare"
+  compiler_flag: "-Wformat=2"
+  compiler_flag: "-Werror"
+  compiler_flag: "-Wstrict-aliasing=2"
+
+  # Be annoying about using doubles places we probably didn't mean to, because
+  # the FPU only does single-precision.
+  compiler_flag: "-Wdouble-promotion"
+
+  # Don't use temp files while compiling.
+  compiler_flag: "-pipe"
+
+  # Stamp the binary with a unique identifier.
+  # TODO(austin): Put these back in.
+  #linker_flag: "-Wl,--build-id=md5"
+  #linker_flag: "-Wl,--hash-style=gnu"
+
+  # Enable debug symbols.
+  compiler_flag: "-g"
+
+  # Commons symbols are weird and not what we want, so just give multiple
+  # declaration errors instead.
+  compiler_flag: "-fno-common"
+
+  compilation_mode_flags {
+    mode: OPT
+
+    # Freescale recommends this combination for reducing cycle count.
+    # http://www.nxp.com/assets/documents/data/en/application-notes/AN4808.pdf
+    compiler_flag: "-O2"
+    compiler_flag: "-finline-functions"
+
+    # This is definitely worth it for us. It makes the FPU a lot more useful,
+    # especially with complex arithmetic, which matters a lot.
+    compiler_flag: "-ffast-math"
+
+    # It seems like this is a good idea, at least for the number crunching code.
+    # Might want to look into moving it to copts on specific rules if the code
+    # size increase becomes a problem.
+    compiler_flag: "-funroll-loops"
+
+    # Disable assertions
+    compiler_flag: "-DNDEBUG"
+
+    # Removal of unused code and data at link time (can this increase binary size in some cases?).
+    compiler_flag: "-ffunction-sections"
+    #compiler_flag: "-fdata-sections"
+    linker_flag: "-Wl,--gc-sections"
+  }
+
+  feature {
+    name: 'include_paths'
+    flag_set {
+      action: 'preprocess-assemble'
+      action: 'c-compile'
+      action: 'c++-compile'
+      action: 'c++-header-parsing'
+      action: 'c++-header-preprocessing'
+      action: 'c++-module-compile'
+      flag_group {
+        flag: '-iquote'
+        flag: '%{quote_include_paths}'
+      }
+      flag_group {
+        flag: '-I%{include_paths}'
+      }
+      flag_group {
+        flag: '-iquote'
+        flag: '%{system_include_paths}'
+      }
+    }
+  }
+}