diff --git a/runners/s3-benchrunner-python/README.md b/runners/s3-benchrunner-python/README.md
index 7d9175ef..48125b6c 100644
--- a/runners/s3-benchrunner-python/README.md
+++ b/runners/s3-benchrunner-python/README.md
@@ -80,7 +80,7 @@ python3 -m pip install --upgrade "boto3[crt]"
 
 ## Building locally
 
-To test against in-development of these libraries, we'll install from source:
+To test against in-development of these libraries, install from source:
 
 First, create a virtual environment, to isolate your dev versions from system defaults:
 ```sh
@@ -89,12 +89,12 @@ source .venv/bin/activate
 ```
 
 Now make a build dir somewhere.
-We're going to pull the source code for dependencies and install them...
+You're going to pull the source code for dependencies and install them...
 ```
 (.venv) cd path/to/my/build/dir
 ```
 
-First, AWS CLI (`--editable` so we can modify its source without reinstalling):
+First, AWS CLI (`--editable` so you can modify its source without reinstalling):
 ```sh
 (.venv) git clone --branch v2 https://github.com/aws/aws-cli.git
 (.venv) python3 -m pip install --editable aws-cli
@@ -124,7 +124,7 @@ Finally aws-crt-python:
 (.venv) python3 -m pip install --editable aws-crt-python
 ```
 pip complains that the newly installed 1.0.0.dev0 clashes
-with the version requirements from other packages, but we ignore this.
+with the version requirements from other packages, but you can ignore this.
 
 Now, you can execute the runner using your virtual environment with all the latest code:
 ```sh
diff --git a/runners/s3-benchrunner-python/scripts/build.py b/runners/s3-benchrunner-python/scripts/build.py
index d6e621ec..cfa47bc7 100755
--- a/runners/s3-benchrunner-python/scripts/build.py
+++ b/runners/s3-benchrunner-python/scripts/build.py
@@ -33,31 +33,16 @@ def fetch_git_repo(url: str, dir: Path, main_branch: str, preferred_branch: Opti
     run(fetch_cmd)
 
 
-def build_cli(work_dir: Path, branch: Optional[str], venv_python: str):
-    cli_dir = work_dir.joinpath('aws-cli')
-
-    # fetch git repo (if necessary)
-    fetch_git_repo('https://github.com/aws/aws-cli.git', cli_dir,
-                   main_branch='v2', preferred_branch=branch)
-
-    # install CLI into virtual env
-    # use --editable so we don't need to reinstall after simple file edits
-    run([venv_python, '-m', 'pip', 'install', '--editable', str(cli_dir)])
-
-
-def build_crt(work_dir: Path, branch: Optional[str], venv_python: str):
-    crt_dir = work_dir.joinpath('aws-crt-python')
-
-    # fetch git repo (if necessary)
-    fetch_git_repo('https://github.com/awslabs/aws-crt-python.git', crt_dir,
-                   main_branch='main', preferred_branch=branch)
-
-    # for faster C compilation
-    os.environ['CMAKE_BUILD_PARALLEL_LEVEL'] = str(os.cpu_count())
+def fetch_and_install(url: str,
+                      dir: Path,
+                      main_branch: str,
+                      preferred_branch: Optional[str],
+                      venv_python: str):
+    fetch_git_repo(url, dir, main_branch, preferred_branch)
 
     # install into virtual env
     # use --editable so we don't need to reinstall after simple file edits
-    run([venv_python, '-m', 'pip', 'install', '--editable', str(crt_dir)])
+    run([venv_python, '-m', 'pip', 'install', '--editable', str(dir)])
 
 
 if __name__ == '__main__':
@@ -74,16 +59,45 @@ def build_crt(work_dir: Path, branch: Optional[str], venv_python: str):
         # upgrade pip to avoid warnings
         run([venv_python, '-m', 'pip', 'install', '--upgrade', 'pip'])
 
-    # install aws-cli from Github
-    build_cli(work_dir, args.branch, venv_python)
-
-    # the runner uses boto3 too
-    run([venv_python, '-m', 'pip', 'install', 'boto3'])
-
-    # install aws-crt-python from Github
-    # (pip complains that the newly installed 1.0.0.dev0 clashes
-    # with the version requirements from awscli, but we ignore this)
-    build_crt(work_dir, args.branch, venv_python)
+    fetch_and_install(
+        url='https://github.com/aws/aws-cli.git',
+        dir=work_dir.joinpath('aws-cli'),
+        main_branch='v2',
+        preferred_branch=args.branch,
+        venv_python=venv_python)
+
+    fetch_and_install(
+        url='https://github.com/boto/boto3.git',
+        dir=work_dir.joinpath('boto3'),
+        main_branch='develop',
+        preferred_branch=args.branch,
+        venv_python=venv_python)
+
+    fetch_and_install(
+        url='https://github.com/boto/s3transfer.git',
+        dir=work_dir.joinpath('s3transfer'),
+        main_branch='develop',
+        preferred_branch=args.branch,
+        venv_python=venv_python)
+
+    fetch_and_install(
+        url='https://github.com/boto/botocore.git',
+        dir=work_dir.joinpath('botocore'),
+        main_branch='develop',
+        preferred_branch=args.branch,
+        venv_python=venv_python)
+
+    # install aws-crt-python
+    # set CMAKE_BUILD_PARALLEL_LEVEL for faster C build
+    # NOTE: (pip complains that the newly installed 1.0.0.dev0 clashes
+    # with the version requirements from other packages, but we ignore this)
+    os.environ['CMAKE_BUILD_PARALLEL_LEVEL'] = str(os.cpu_count())
+    fetch_and_install(
+        url='https://github.com/awslabs/aws-crt-python.git',
+        dir=work_dir.joinpath('aws-crt-python'),
+        main_branch='main',
+        preferred_branch=args.branch,
+        venv_python=venv_python)
 
     runner_dir = Path(__file__).parent.parent.resolve()  # normalize path
     runner_py = str(runner_dir.joinpath('benchrunner.py'))