diff --git a/.bazelversion b/.bazelversion
index 7c69a55dbb..fae6e3d04b 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-3.7.0
+4.2.1
diff --git a/tools/cross-toolchain/configs/.latest.bazelrc b/tools/cross-toolchain/configs/.latest.bazelrc
index 37da2b3c9e..7cc88c9df8 100644
--- a/tools/cross-toolchain/configs/.latest.bazelrc
+++ b/tools/cross-toolchain/configs/.latest.bazelrc
@@ -19,13 +19,13 @@
 # Specifically, it includes all toolchain/platform flags
 # This file is used for testing purposes.
 
-build:remote --host_javabase=//tools/cross-toolchain/configs/clang/bazel_3.7.0/java:jdk
-build:remote --javabase=//tools/cross-toolchain/configs/clang/bazel_3.7.0/java:jdk
-build:remote --crosstool_top=//tools/cross-toolchain/configs/clang/bazel_3.7.0/cc:toolchain
-build:remote --extra_toolchains=//tools/cross-toolchain/configs/clang/bazel_3.7.0/config:cc-toolchain
-build:remote --extra_execution_platforms=//tools/cross-toolchain/configs/clang/bazel_3.7.0/config:platform
-build:remote --host_platform=//tools/cross-toolchain/configs/clang/bazel_3.7.0/config:platform
-build:remote --platforms=//tools/cross-toolchain/configs/clang/bazel_3.7.0/config:platform
+build:remote --host_javabase=//tools/cross-toolchain/configs/clang/bazel_4.2.1/java:jdk
+build:remote --javabase=//tools/cross-toolchain/configs/clang/bazel_4.2.1/java:jdk
+build:remote --crosstool_top=//tools/cross-toolchain/configs/clang/bazel_4.2.1/cc:toolchain
+build:remote --extra_toolchains=//tools/cross-toolchain/configs/clang/bazel_4.2.1/config:cc-toolchain
+build:remote --extra_execution_platforms=//tools/cross-toolchain/configs/clang/bazel_4.2.1/config:platform
+build:remote --host_platform=//tools/cross-toolchain/configs/clang/bazel_4.2.1/config:platform
+build:remote --platforms=//tools/cross-toolchain/configs/clang/bazel_4.2.1/config:platform
 
 # Import the default bazelrc file in bazel-toolchains repo.
 # This will only work for tests executed from bazel-toolchains
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/BUILD b/tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/BUILD
similarity index 99%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/BUILD
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/BUILD
index 3fb72a67b0..718caba4d3 100755
--- a/tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/BUILD
+++ b/tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/BUILD
@@ -137,6 +137,7 @@ cc_toolchain_config(
     tool_paths = {
         "ar": "/usr/bin/ar",
         "ld": "/usr/bin/ld",
+        "llvm-cov": "/usr/bin/llvm-cov",
         "cpp": "/usr/bin/cpp",
         "gcc": "/usr/bin/clang",
         "dwp": "/usr/bin/dwp",
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/armeabi_cc_toolchain_config.bzl b/tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/armeabi_cc_toolchain_config.bzl
similarity index 100%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/armeabi_cc_toolchain_config.bzl
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/armeabi_cc_toolchain_config.bzl
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/builtin_include_directory_paths b/tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/builtin_include_directory_paths
similarity index 100%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/builtin_include_directory_paths
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/builtin_include_directory_paths
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/cc_toolchain_config.bzl b/tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/cc_toolchain_config.bzl
similarity index 99%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/cc_toolchain_config.bzl
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/cc_toolchain_config.bzl
index 6fca87a72f..5dbaa86ab2 100755
--- a/tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/cc_toolchain_config.bzl
+++ b/tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/cc_toolchain_config.bzl
@@ -16,10 +16,12 @@
 
 load(
     "@bazel_tools//tools/cpp:cc_toolchain_config_lib.bzl",
+    "action_config",
     "feature",
     "feature_set",
     "flag_group",
     "flag_set",
+    "tool",
     "tool_path",
     "variable_with_value",
     "with_feature_set",
@@ -147,6 +149,17 @@ def _impl(ctx):
     ]
     action_configs = []
 
+    llvm_cov_action = action_config(
+        action_name = ACTION_NAMES.llvm_cov,
+        tools = [
+            tool(
+                path = ctx.attr.tool_paths["llvm-cov"],
+            ),
+        ],
+    )
+
+    action_configs.append(llvm_cov_action)
+
     supports_pic_feature = feature(
         name = "supports_pic",
         enabled = True,
@@ -1226,6 +1239,7 @@ def _impl(ctx):
         abi_version = ctx.attr.abi_version,
         abi_libc_version = ctx.attr.abi_libc_version,
         tool_paths = tool_paths,
+        builtin_sysroot = ctx.attr.builtin_sysroot,
     )
 
 cc_toolchain_config = rule(
@@ -1252,6 +1266,7 @@ cc_toolchain_config = rule(
         "coverage_compile_flags": attr.string_list(),
         "coverage_link_flags": attr.string_list(),
         "supports_start_end_lib": attr.bool(),
+        "builtin_sysroot": attr.string(),
     },
     provides = [CcToolchainConfigInfo],
 )
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/cc_wrapper.sh b/tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/cc_wrapper.sh
similarity index 100%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/cc_wrapper.sh
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/cc_wrapper.sh
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/module.modulemap b/tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/module.modulemap
similarity index 100%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/cc/module.modulemap
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/cc/module.modulemap
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/config/BUILD b/tools/cross-toolchain/configs/clang/bazel_4.2.1/config/BUILD
similarity index 94%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/config/BUILD
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/config/BUILD
index 7c4ea88443..593c5e88f0 100644
--- a/tools/cross-toolchain/configs/clang/bazel_3.7.0/config/BUILD
+++ b/tools/cross-toolchain/configs/clang/bazel_4.2.1/config/BUILD
@@ -29,7 +29,7 @@ toolchain(
         "@bazel_tools//platforms:linux",
         "@bazel_tools//platforms:x86_64",
     ],
-    toolchain = "//tools/cross-toolchain/configs/clang/bazel_3.7.0/cc:cc-compiler-k8",
+    toolchain = "//tools/cross-toolchain/configs/clang/bazel_4.2.1/cc:cc-compiler-k8",
     toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
 )
 
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/java/BUILD b/tools/cross-toolchain/configs/clang/bazel_4.2.1/java/BUILD
similarity index 100%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/java/BUILD
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/java/BUILD
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/prysm_toolchains/BUILD.bazel b/tools/cross-toolchain/configs/clang/bazel_4.2.1/prysm_toolchains/BUILD.bazel
similarity index 100%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/prysm_toolchains/BUILD.bazel
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/prysm_toolchains/BUILD.bazel
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/prysm_toolchains/WORKSPACE b/tools/cross-toolchain/configs/clang/bazel_4.2.1/prysm_toolchains/WORKSPACE
similarity index 100%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/prysm_toolchains/WORKSPACE
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/prysm_toolchains/WORKSPACE
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/prysm_toolchains/cc_toolchain_config_linux_arm64.bzl b/tools/cross-toolchain/configs/clang/bazel_4.2.1/prysm_toolchains/cc_toolchain_config_linux_arm64.bzl
similarity index 100%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/prysm_toolchains/cc_toolchain_config_linux_arm64.bzl
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/prysm_toolchains/cc_toolchain_config_linux_arm64.bzl
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/prysm_toolchains/cc_toolchain_config_osx.bzl b/tools/cross-toolchain/configs/clang/bazel_4.2.1/prysm_toolchains/cc_toolchain_config_osx.bzl
similarity index 100%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/prysm_toolchains/cc_toolchain_config_osx.bzl
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/prysm_toolchains/cc_toolchain_config_osx.bzl
diff --git a/tools/cross-toolchain/configs/clang/bazel_3.7.0/prysm_toolchains/cc_toolchain_config_windows.bzl b/tools/cross-toolchain/configs/clang/bazel_4.2.1/prysm_toolchains/cc_toolchain_config_windows.bzl
similarity index 100%
rename from tools/cross-toolchain/configs/clang/bazel_3.7.0/prysm_toolchains/cc_toolchain_config_windows.bzl
rename to tools/cross-toolchain/configs/clang/bazel_4.2.1/prysm_toolchains/cc_toolchain_config_windows.bzl
diff --git a/tools/cross-toolchain/configs/versions.bzl b/tools/cross-toolchain/configs/versions.bzl
index ca71c4fc9d..af82679944 100644
--- a/tools/cross-toolchain/configs/versions.bzl
+++ b/tools/cross-toolchain/configs/versions.bzl
@@ -3,7 +3,7 @@
 """Definitions to be used in rbe_repo attr of an rbe_autoconf rule  """
 toolchain_config_spec0 = struct(config_repos = ["prysm_toolchains"], create_cc_configs = True, create_java_configs = True, env = {"BAZEL_COMPILER": "clang", "BAZEL_LINKLIBS": "-l%:libstdc++.a", "BAZEL_LINKOPTS": "-lm:-static-libgcc", "BAZEL_USE_LLVM_NATIVE_COVERAGE": "1", "GCOV": "llvm-profdata", "CC": "clang", "CXX": "clang++"}, java_home = "/usr/lib/jvm/java-8-openjdk-amd64", name = "clang")
 _TOOLCHAIN_CONFIG_SPECS = [toolchain_config_spec0]
-_BAZEL_TO_CONFIG_SPEC_NAMES = {"3.7.0": ["clang"]}
+_BAZEL_TO_CONFIG_SPEC_NAMES = {"4.2.1": ["clang"]}
 LATEST = "sha256:bd40e9a43b983c8b06079d14a0530100d6e1d59796616ca1d8b3902a197c97b1"
 CONTAINER_TO_CONFIG_SPEC_NAMES = {"sha256:bd40e9a43b983c8b06079d14a0530100d6e1d59796616ca1d8b3902a197c97b1": ["clang"]}
 _DEFAULT_TOOLCHAIN_CONFIG_SPEC = toolchain_config_spec0