diff --git a/toolchain/cc_toolchain_config.bzl b/toolchain/cc_toolchain_config.bzl
index 9dbb41db..fcfe32e5 100644
--- a/toolchain/cc_toolchain_config.bzl
+++ b/toolchain/cc_toolchain_config.bzl
@@ -364,6 +364,29 @@ def cc_toolchain_config(
     if compiler_configuration["unfiltered_compile_flags"] != None:
         unfiltered_compile_flags = _fmt_flags(compiler_configuration["unfiltered_compile_flags"], toolchain_path_prefix)
 
+    if compiler_configuration["extra_compile_flags"] != None:
+        compile_flags.extend(_fmt_flags(compiler_configuration["extra_compile_flags"], toolchain_path_prefix))
+    if compiler_configuration["extra_cxx_flags"] != None:
+        cxx_flags.extend(_fmt_flags(compiler_configuration["extra_cxx_flags"], toolchain_path_prefix))
+    if compiler_configuration["extra_link_flags"] != None:
+        link_flags.extend(_fmt_flags(compiler_configuration["extra_link_flags"], toolchain_path_prefix))
+    if compiler_configuration["extra_archive_flags"] != None:
+        archive_flags.extend(_fmt_flags(compiler_configuration["extra_archive_flags"], toolchain_path_prefix))
+    if compiler_configuration["extra_link_libs"] != None:
+        link_libs.extend(_fmt_flags(compiler_configuration["extra_link_libs"], toolchain_path_prefix))
+    if compiler_configuration["extra_opt_compile_flags"] != None:
+        opt_compile_flags.extend(_fmt_flags(compiler_configuration["extra_opt_compile_flags"], toolchain_path_prefix))
+    if compiler_configuration["extra_opt_link_flags"] != None:
+        opt_link_flags.extend(_fmt_flags(compiler_configuration["extra_opt_link_flags"], toolchain_path_prefix))
+    if compiler_configuration["extra_dbg_compile_flags"] != None:
+        dbg_compile_flags.extend(_fmt_flags(compiler_configuration["extra_dbg_compile_flags"], toolchain_path_prefix))
+    if compiler_configuration["extra_coverage_compile_flags"] != None:
+        coverage_compile_flags.extend(_fmt_flags(compiler_configuration["extra_coverage_compile_flags"], toolchain_path_prefix))
+    if compiler_configuration["extra_coverage_link_flags"] != None:
+        coverage_link_flags.extend(_fmt_flags(compiler_configuration["extra_coverage_link_flags"], toolchain_path_prefix))
+    if compiler_configuration["extra_unfiltered_compile_flags"] != None:
+        unfiltered_compile_flags.extend(_fmt_flags(compiler_configuration["extra_unfiltered_compile_flags"], toolchain_path_prefix))
+
     # Source: https://cs.opensource.google/bazel/bazel/+/master:tools/cpp/unix_cc_toolchain_config.bzl
     unix_cc_toolchain_config(
         name = name,
diff --git a/toolchain/internal/configure.bzl b/toolchain/internal/configure.bzl
index acc5135e..4803bd40 100644
--- a/toolchain/internal/configure.bzl
+++ b/toolchain/internal/configure.bzl
@@ -174,6 +174,17 @@ def llvm_config_impl(rctx):
         extra_compiler_files = rctx.attr.extra_compiler_files,
         extra_exec_compatible_with = rctx.attr.extra_exec_compatible_with,
         extra_target_compatible_with = rctx.attr.extra_target_compatible_with,
+        extra_compile_flags_dict = rctx.attr.extra_compile_flags,
+        extra_cxx_flags_dict = rctx.attr.extra_cxx_flags,
+        extra_link_flags_dict = rctx.attr.extra_link_flags,
+        extra_archive_flags_dict = rctx.attr.extra_archive_flags,
+        extra_link_libs_dict = rctx.attr.extra_link_libs,
+        extra_opt_compile_flags_dict = rctx.attr.extra_opt_compile_flags,
+        extra_opt_link_flags_dict = rctx.attr.extra_opt_link_flags,
+        extra_dbg_compile_flags_dict = rctx.attr.extra_dbg_compile_flags,
+        extra_coverage_compile_flags_dict = rctx.attr.extra_coverage_compile_flags,
+        extra_coverage_link_flags_dict = rctx.attr.extra_coverage_link_flags,
+        extra_unfiltered_compile_flags_dict = rctx.attr.extra_unfiltered_compile_flags,
     )
     exec_dl_ext = "dylib" if os == "darwin" else "so"
     cc_toolchains_str, toolchain_labels_str = _cc_toolchains_str(
@@ -389,6 +400,17 @@ cc_toolchain_config(
       "coverage_compile_flags": {coverage_compile_flags},
       "coverage_link_flags": {coverage_link_flags},
       "unfiltered_compile_flags": {unfiltered_compile_flags},
+      "extra_compile_flags": {extra_compile_flags},
+      "extra_cxx_flags": {extra_cxx_flags},
+      "extra_link_flags": {extra_link_flags},
+      "extra_archive_flags": {extra_archive_flags},
+      "extra_link_libs": {extra_link_libs},
+      "extra_opt_compile_flags": {extra_opt_compile_flags},
+      "extra_opt_link_flags": {extra_opt_link_flags},
+      "extra_dbg_compile_flags": {extra_dbg_compile_flags},
+      "extra_coverage_compile_flags": {extra_coverage_compile_flags},
+      "extra_coverage_link_flags": {extra_coverage_link_flags},
+      "extra_unfiltered_compile_flags": {extra_unfiltered_compile_flags},
     }},
     cxx_builtin_include_directories = {cxx_builtin_include_directories},
     major_llvm_version = {major_llvm_version},
@@ -562,6 +584,17 @@ cc_toolchain(
         coverage_compile_flags = _list_to_string(_dict_value(toolchain_info.coverage_compile_flags_dict, target_pair)),
         coverage_link_flags = _list_to_string(_dict_value(toolchain_info.coverage_link_flags_dict, target_pair)),
         unfiltered_compile_flags = _list_to_string(_dict_value(toolchain_info.unfiltered_compile_flags_dict, target_pair)),
+        extra_compile_flags = _list_to_string(_dict_value(toolchain_info.extra_compile_flags_dict, target_pair)),
+        extra_cxx_flags = _list_to_string(_dict_value(toolchain_info.extra_cxx_flags_dict, target_pair)),
+        extra_link_flags = _list_to_string(_dict_value(toolchain_info.extra_link_flags_dict, target_pair)),
+        extra_archive_flags = _list_to_string(_dict_value(toolchain_info.extra_archive_flags_dict, target_pair)),
+        extra_link_libs = _list_to_string(_dict_value(toolchain_info.extra_link_libs_dict, target_pair)),
+        extra_opt_compile_flags = _list_to_string(_dict_value(toolchain_info.extra_opt_compile_flags_dict, target_pair)),
+        extra_opt_link_flags = _list_to_string(_dict_value(toolchain_info.extra_opt_link_flags_dict, target_pair)),
+        extra_dbg_compile_flags = _list_to_string(_dict_value(toolchain_info.extra_dbg_compile_flags_dict, target_pair)),
+        extra_coverage_compile_flags = _list_to_string(_dict_value(toolchain_info.extra_coverage_compile_flags_dict, target_pair)),
+        extra_coverage_link_flags = _list_to_string(_dict_value(toolchain_info.extra_coverage_link_flags_dict, target_pair)),
+        extra_unfiltered_compile_flags = _list_to_string(_dict_value(toolchain_info.extra_unfiltered_compile_flags_dict, target_pair)),
         extra_files_str = extra_files_str,
         cxx_builtin_include_directories = _list_to_string(filtered_cxx_builtin_include_directories),
         extra_compiler_files = ("\"%s\"," % str(toolchain_info.extra_compiler_files)) if toolchain_info.extra_compiler_files else "",
diff --git a/toolchain/internal/repo.bzl b/toolchain/internal/repo.bzl
index 0f17cb56..b127a906 100644
--- a/toolchain/internal/repo.bzl
+++ b/toolchain/internal/repo.bzl
@@ -249,6 +249,95 @@ _compiler_configuration_attrs = {
                "target OS and arch pair you want to override " +
                "({}); empty key overrides all.".format(_target_pairs)),
     ),
+    # Same as the above flags, but instead of overriding the defaults, it just adds extras
+    "extra_compile_flags": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Extra compile_flags, added after default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
+    "extra_cxx_flags": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Extra cxx_flags, added after default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
+    "extra_link_flags": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Extra link_flags, added after the default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
+    "extra_archive_flags": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Extra archive_flags, added after the default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
+    "extra_link_libs": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Extra for link_libs, added after the default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
+    "extra_opt_compile_flags": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Extra opt_compile_flags, added after the default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
+    "extra_opt_link_flags": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Extra opt_link_flags, added after the default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
+    "extra_dbg_compile_flags": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Extra dbg_compile_flags, added after the default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
+    "extra_coverage_compile_flags": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Extra coverage_compile_flags, added after the default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
+    "extra_coverage_link_flags": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Extra coverage_link_flags, added after the default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
+    "extra_unfiltered_compile_flags": attr.string_list_dict(
+        mandatory = False,
+        doc = ("Extra unfiltered_compile_flags, added after the default values. " +
+               "`{toolchain_path_prefix}` in the flags will be substituted by the path " +
+               "to the root LLVM distribution directory. Provide one list for each " +
+               "target OS and arch pair you want to override " +
+               "({}); empty key overrides all.".format(_target_pairs)),
+    ),
     "target_settings": attr.string_list_dict(
         mandatory = False,
         doc = ("Override the toolchain's `target_settings` attribute."),