diff --git a/readthedocs/doc_builder/director.py b/readthedocs/doc_builder/director.py
index 0fa9b865e35..4b7b9d406ec 100644
--- a/readthedocs/doc_builder/director.py
+++ b/readthedocs/doc_builder/director.py
@@ -29,6 +29,7 @@
 from readthedocs.projects.constants import BUILD_COMMANDS_OUTPUT_PATH_HTML
 from readthedocs.projects.constants import GENERIC
 from readthedocs.projects.exceptions import RepositoryError
+from readthedocs.projects.models import Feature
 from readthedocs.projects.notifications import MESSAGE_PROJECT_SSH_KEY_WITH_WRITE_ACCESS
 from readthedocs.projects.signals import after_build
 from readthedocs.projects.signals import before_build
@@ -724,6 +725,21 @@ def build_docs_class(self, builder_class):
         success = builder.build()
         return success
 
+    def _add_parallel_env_var(self, env):
+        cpus = os.cpu_count()
+        # These variables are useful for projects that compile libraries during the build.
+        env.update(
+            {
+                # https://cmake.org/cmake/help/latest/envvar/CMAKE_BUILD_PARALLEL_LEVEL.html
+                "CMAKE_BUILD_PARALLEL_LEVEL": cpus,
+                # https://www.gnu.org/software/make/manual/html_node/Options_002fRecursion.html
+                "MAKEFLAGS": f"-j {cpus}",
+                # Pillow and other libraries use this variable
+                # https://pillow.readthedocs.io/en/stable/installation/building-from-source.html#build-options
+                "MAX_CONCURRENCY": cpus,
+            }
+        )
+
     def _add_git_ssh_command_env_var(self, env):
         if settings.ALLOW_PRIVATE_REPOS:
             # Set GIT_SSH_COMMAND to use ssh with options that disable host key checking
@@ -812,6 +828,9 @@ def get_build_env_vars(self):
 
         self._add_git_ssh_command_env_var(env)
 
+        if self.data.project.has_feature(Feature.BUILD_IN_PARALLEL):
+            self._add_parallel_env_var(env)
+
         # Update environment from Project's specific environment variables,
         # avoiding to expose private environment variables
         # if the version is external (i.e. a PR build).
diff --git a/readthedocs/vcs_support/backends/git.py b/readthedocs/vcs_support/backends/git.py
index ffd54a61b92..8b1bb881b37 100644
--- a/readthedocs/vcs_support/backends/git.py
+++ b/readthedocs/vcs_support/backends/git.py
@@ -39,10 +39,30 @@ def _get_clone_url(self):
             return f"{parsed_url.scheme}://$READTHEDOCS_GIT_CLONE_TOKEN@{parsed_url.netloc}{parsed_url.path}"
         return self.repo_url
 
+    def _set_parallel_configs(self):
+        """
+        Set git configs to enable parallelization.
+        """
+        # https://git-scm.com/docs/git-config#Documentation/git-config.txt-fetchparallel
+        self.run("git", "config", "--global", "fetch.parallel", "0")
+        # https://git-scm.com/docs/git-config#Documentation/git-config.txt-checkoutworkers
+        self.run("git", "config", "--global", "checkout.workers", "0")
+        # https://git-scm.com/docs/git-config#Documentation/git-config.txt-checkoutthresholdForParallelism
+        self.run("git", "config", "--global", "checkout.thresholdForParallelism", "100")
+        # https://git-scm.com/docs/git-config#Documentation/git-config.txt-submodulefetchJobs
+        self.run("git", "config", "--global", "submodule.fetchJobs", "0")
+        # https://git-scm.com/docs/git-config#Documentation/git-config.txt-packthreads
+        self.run("git", "config", "--global", "pack.threads", "0")
+
     def update(self):
         """Clone and/or fetch remote repository."""
         super().update()
 
+        from readthedocs.projects.models import Feature
+
+        if self.project.has_feature(Feature.BUILD_IN_PARALLEL):
+            self._set_parallel_configs()
+
         if self.project.git_checkout_command:
             # Run custom checkout step if defined
             if isinstance(self.project.git_checkout_command, list):