diff --git a/python/prompt_bench/container.py b/python/prompt_bench/container.py
new file mode 100644
index 0000000..dc73fcc
--- /dev/null
+++ b/python/prompt_bench/container.py
@@ -0,0 +1,81 @@
+"""Docker container lifecycle management for vLLM."""
+
+from __future__ import annotations
+
+import logging
+import subprocess
+
+logger = logging.getLogger(__name__)
+
+CONTAINER_NAME = "vllm-bench"
+VLLM_IMAGE = "vllm/vllm-openai:v0.8.5"
+
+
+def start_vllm(
+    *,
+    model: str,
+    port: int,
+    model_dir: str,
+    gpu_memory_utilization: float,
+) -> None:
+    """Start a vLLM container serving the given model.
+
+    Args:
+        model: HuggingFace model directory name (relative to model_dir).
+        port: Host port to bind.
+        model_dir: Host path containing HuggingFace model directories.
+        gpu_memory_utilization: Fraction of GPU memory to use (0-1).
+    """
+    command = [
+        "docker",
+        "run",
+        "-d",
+        "--name",
+        CONTAINER_NAME,
+        "--device=nvidia.com/gpu=all",
+        "--ipc=host",
+        "-v",
+        f"{model_dir}:/models",
+        "-p",
+        f"{port}:8000",
+        VLLM_IMAGE,
+        "--model",
+        f"/models/{model}",
+        "--served-model-name",
+        model,
+        "--gpu-memory-utilization",
+        str(gpu_memory_utilization),
+        "--max-model-len",
+        "4096",
+    ]
+    logger.info("Starting vLLM container with model: %s", model)
+    result = subprocess.run(command, capture_output=True, text=True, check=False)
+    if result.returncode != 0:
+        msg = f"Failed to start vLLM container: {result.stderr.strip()}"
+        raise RuntimeError(msg)
+    logger.info("vLLM container started: %s", result.stdout.strip()[:12])
+
+
+def stop_vllm() -> None:
+    """Stop and remove the vLLM benchmark container."""
+    logger.info("Stopping vLLM container")
+    subprocess.run(["docker", "stop", CONTAINER_NAME], capture_output=True, check=False)
+    subprocess.run(["docker", "rm", CONTAINER_NAME], capture_output=True, check=False)
+    logger.info("vLLM container stopped and removed")
+
+
+def check_gpu_free() -> None:
+    """Warn if GPU-heavy processes (e.g. Ollama) are running."""
+    result = subprocess.run(
+        ["nvidia-smi", "--query-compute-apps=pid,process_name", "--format=csv,noheader"],
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+    if result.returncode != 0:
+        logger.warning("Could not query GPU processes: %s", result.stderr.strip())
+        return
+    processes = result.stdout.strip()
+    if processes:
+        logger.warning("GPU processes detected:\n%s", processes)
+        logger.warning("Consider stopping Ollama (sudo systemctl stop ollama) before benchmarking")
diff --git a/python/prompt_bench/main.py b/python/prompt_bench/main.py
new file mode 100644
index 0000000..0d39e69
--- /dev/null
+++ b/python/prompt_bench/main.py
@@ -0,0 +1,218 @@
+"""CLI entry point for the prompt benchmarking system."""
+
+from __future__ import annotations
+
+import json
+import logging
+import time
+import tomllib
+from concurrent.futures import ThreadPoolExecutor, as_completed
+from pathlib import Path
+from typing import Annotated
+
+import typer
+
+from python.prompt_bench.container import check_gpu_free, start_vllm, stop_vllm
+from python.prompt_bench.downloader import is_model_present
+from python.prompt_bench.models import BenchmarkConfig
+from python.prompt_bench.vllm_client import VLLMClient
+
+logger = logging.getLogger(__name__)
+
+
+def discover_prompts(input_dir: Path) -> list[Path]:
+    """Find all .txt files in the input directory."""
+    prompts = list(input_dir.glob("*.txt"))
+    if not prompts:
+        message = f"No .txt files found in {input_dir}"
+        raise FileNotFoundError(message)
+    return prompts
+
+
+def _run_prompt(
+    client: VLLMClient,
+    prompt_path: Path,
+    *,
+    repo: str,
+    model_dir_name: str,
+    model_output: Path,
+    temperature: float,
+) -> tuple[bool, float]:
+    """Run a single prompt. Returns (success, elapsed_seconds)."""
+    filename = prompt_path.name
+    output_path = model_output / filename
+    start = time.monotonic()
+    try:
+        prompt_text = prompt_path.read_text()
+        response = client.complete(prompt_text, model_dir_name, temperature=temperature)
+        output_path.write_text(response)
+        elapsed = time.monotonic() - start
+        logger.info("Completed: %s / %s in %.2fs", repo, filename, elapsed)
+    except Exception:
+        elapsed = time.monotonic() - start
+        error_path = model_output / f"{filename}.error"
+        logger.exception("Failed: %s / %s after %.2fs", repo, filename, elapsed)
+        error_path.write_text(f"Error processing {filename}")
+        return False, elapsed
+    return True, elapsed
+
+
+def benchmark_model(
+    client: VLLMClient,
+    prompts: list[Path],
+    *,
+    repo: str,
+    model_dir_name: str,
+    model_output: Path,
+    temperature: float,
+    concurrency: int,
+) -> tuple[int, int]:
+    """Run all prompts against a single model in parallel.
+
+    vLLM batches concurrent requests internally, so submitting many at once is
+    significantly faster than running them serially.
+    """
+    pending = [prompt for prompt in prompts if not (model_output / prompt.name).exists()]
+    skipped = len(prompts) - len(pending)
+    if skipped:
+        logger.info("Skipping %d prompts with existing output for %s", skipped, repo)
+
+    if not pending:
+        logger.info("Nothing to do for %s", repo)
+        return 0, 0
+
+    completed = 0
+    failed = 0
+    latencies: list[float] = []
+
+    wall_start = time.monotonic()
+    with ThreadPoolExecutor(max_workers=concurrency) as executor:
+        futures = [
+            executor.submit(
+                _run_prompt,
+                client,
+                prompt_path,
+                repo=repo,
+                model_dir_name=model_dir_name,
+                model_output=model_output,
+                temperature=temperature,
+            )
+            for prompt_path in pending
+        ]
+        for future in as_completed(futures):
+            success, elapsed = future.result()
+            latencies.append(elapsed)
+            if success:
+                completed += 1
+            else:
+                failed += 1
+    wall_elapsed = time.monotonic() - wall_start
+
+    attempted = completed + failed
+    avg_latency = sum(latencies) / attempted
+    throughput = attempted / wall_elapsed if wall_elapsed > 0 else 0.0
+    timing = {
+        "repo": repo,
+        "wall_seconds": wall_elapsed,
+        "attempted": attempted,
+        "completed": completed,
+        "failed": failed,
+        "avg_latency_seconds": avg_latency,
+        "throughput_prompts_per_second": throughput,
+        "concurrency": concurrency,
+    }
+    timing_path = model_output / "_timing.json"
+    timing_path.write_text(json.dumps(timing, indent=2))
+
+    return completed, failed
+
+
+def run_benchmark(
+    config: BenchmarkConfig,
+    input_dir: Path,
+    output_dir: Path,
+) -> None:
+    """Execute the benchmark across all models and prompts."""
+    prompts = discover_prompts(input_dir)
+    logger.info("Found %d prompts in %s", len(prompts), input_dir)
+
+    check_gpu_free()
+
+    total_completed = 0
+    total_failed = 0
+
+    for repo in config.models:
+        if not is_model_present(repo, config.model_dir):
+            logger.warning("Skipping (not downloaded): %s", repo)
+            continue
+
+        model_output = output_dir / repo
+        model_output.mkdir(parents=True, exist_ok=True)
+
+        logger.info("=== Benchmarking model: %s ===", repo)
+
+        stop_vllm()
+        try:
+            start_vllm(
+                model=repo,
+                port=config.port,
+                model_dir=config.model_dir,
+                gpu_memory_utilization=config.gpu_memory_utilization,
+            )
+        except RuntimeError:
+            logger.exception("Failed to start vLLM for %s, skipping", repo)
+            continue
+        logger.info("vLLM started for %s", repo)
+        try:
+            with VLLMClient(port=config.port, timeout=config.timeout) as client:
+                client.wait_ready(max_wait=config.vllm_startup_timeout)
+                completed, failed = benchmark_model(
+                    client,
+                    prompts,
+                    repo=repo,
+                    model_dir_name=repo,
+                    model_output=model_output,
+                    temperature=config.temperature,
+                    concurrency=config.concurrency,
+                )
+                total_completed += completed
+                total_failed += failed
+        finally:
+            stop_vllm()
+
+    logger.info("=== Benchmark complete ===")
+    logger.info("Completed: %d | Failed: %d", total_completed, total_failed)
+
+
+def main(
+    input_dir: Annotated[Path, typer.Argument(help="Directory containing input .txt prompt files")],
+    config: Annotated[Path, typer.Option(help="Path to TOML config file")] = Path("bench.toml"),
+    output_dir: Annotated[Path, typer.Option(help="Output directory for results")] = Path("output"),
+    log_level: Annotated[str, typer.Option(help="Log level")] = "INFO",
+) -> None:
+    """Run prompts through multiple LLMs via vLLM and save results."""
+    logging.basicConfig(level=log_level, format="%(asctime)s %(levelname)s %(name)s: %(message)s")
+
+    if not input_dir.is_dir():
+        message = f"Input directory does not exist: {input_dir}"
+        raise typer.BadParameter(message)
+    if not config.is_file():
+        message = f"Config file does not exist: {config}"
+        raise typer.BadParameter(message)
+
+    with config.open("rb") as file:
+        raw = tomllib.load(file)
+
+    benchmark_config = BenchmarkConfig(**raw)
+    output_dir.mkdir(parents=True, exist_ok=True)
+
+    run_benchmark(benchmark_config, input_dir, output_dir)
+
+
+def cli() -> None:
+    """Typer entry point."""
+    typer.run(main)
+
+
+if __name__ == "__main__":
+    cli()
diff --git a/python/prompt_bench/models.py b/python/prompt_bench/models.py
index f07084b..1abae25 100644
--- a/python/prompt_bench/models.py
+++ b/python/prompt_bench/models.py
@@ -15,3 +15,4 @@ class BenchmarkConfig(BaseModel):
     temperature: float = 0.0
     timeout: int = 300
     concurrency: int = 4
+    vllm_startup_timeout: int = 900
diff --git a/python/prompt_bench/vllm_client.py b/python/prompt_bench/vllm_client.py
new file mode 100644
index 0000000..b7d9045
--- /dev/null
+++ b/python/prompt_bench/vllm_client.py
@@ -0,0 +1,68 @@
+"""OpenAI-compatible client for vLLM's API."""
+
+from __future__ import annotations
+
+import logging
+import time
+from typing import Self
+
+import httpx
+
+logger = logging.getLogger(__name__)
+
+READY_POLL_INTERVAL = 2.0
+
+
+class VLLMClient:
+    """Talk to a vLLM server via its OpenAI-compatible API.
+
+    Args:
+        host: vLLM host.
+        port: vLLM port.
+        timeout: Per-request timeout in seconds.
+    """
+
+    def __init__(self, *, host: str = "localhost", port: int = 8000, timeout: int = 300) -> None:
+        """Create a client connected to a vLLM server."""
+        self._client = httpx.Client(base_url=f"http://{host}:{port}", timeout=timeout)
+
+    def wait_ready(self, max_wait: int) -> None:
+        """Poll /v1/models until the server is ready or timeout."""
+        deadline = time.monotonic() + max_wait
+        while time.monotonic() < deadline:
+            try:
+                response = self._client.get("/v1/models")
+                if response.is_success:
+                    logger.info("vLLM server is ready")
+                    return
+            except httpx.TransportError:
+                pass
+            time.sleep(READY_POLL_INTERVAL)
+        msg = f"vLLM server not ready after {max_wait}s"
+        raise TimeoutError(msg)
+
+    def complete(self, prompt: str, model: str, *, temperature: float = 0.0, max_tokens: int = 4096) -> str:
+        """Send a prompt to /v1/completions and return the response text."""
+        payload = {
+            "model": model,
+            "prompt": prompt,
+            "temperature": temperature,
+            "max_tokens": max_tokens,
+        }
+        logger.info("Sending prompt to %s (%d chars)", model, len(prompt))
+        response = self._client.post("/v1/completions", json=payload)
+        response.raise_for_status()
+        data = response.json()
+        return data["choices"][0]["text"]
+
+    def close(self) -> None:
+        """Close the HTTP client."""
+        self._client.close()
+
+    def __enter__(self) -> Self:
+        """Enter the context manager."""
+        return self
+
+    def __exit__(self, *args: object) -> None:
+        """Close the HTTP client on exit."""
+        self.close()