diff --git a/test/fuzz/test_runner.py b/test/fuzz/test_runner.py
--- a/test/fuzz/test_runner.py
+++ b/test/fuzz/test_runner.py
@@ -6,6 +6,7 @@
 """
 
 import argparse
+from concurrent.futures import ThreadPoolExecutor, as_completed
 import configparser
 import logging
 import os
@@ -35,6 +36,12 @@
         '--exclude',
         help="A comma-separated list of targets to exclude",
     )
+    parser.add_argument(
+        '--par',
+        type=int,
+        default=4,
+        help='How many targets to merge or execute in parallel.',
+    )
     parser.add_argument(
         'seed_dir',
         help='The seed corpus to run on (must contain subfolders for each fuzz target).',
@@ -144,29 +151,33 @@
             "subprocess timed out: Currently only libFuzzer is supported")
         sys.exit(1)
 
-    if args.m_dir:
-        merge_inputs(
+    with ThreadPoolExecutor(max_workers=args.par) as fuzz_pool:
+        if args.m_dir:
+            merge_inputs(
+                fuzz_pool=fuzz_pool,
+                corpus=args.seed_dir,
+                test_list=test_list_selection,
+                test_dir=test_dir,
+                merge_dir=args.m_dir,
+            )
+            return
+
+        run_once(
+            fuzz_pool=fuzz_pool,
             corpus=args.seed_dir,
             test_list=test_list_selection,
-            build_dir=config["environment"]["BUILDDIR"],
-            merge_dir=args.m_dir,
+            test_dir=test_dir,
+            use_valgrind=args.valgrind,
         )
-        return
-
-    run_once(
-        corpus=args.seed_dir,
-        test_list=test_list_selection,
-        test_dir=test_dir,
-        use_valgrind=args.valgrind,
-    )
 
 
-def merge_inputs(*, corpus, test_list, build_dir, merge_dir):
+def merge_inputs(*, fuzz_pool, corpus, test_list, test_dir, merge_dir):
     logging.info(
         "Merge the inputs in the passed dir into the seed_dir. Passed dir {}".format(merge_dir))
+    jobs = []
     for t in test_list:
         args = [
-            os.path.join(build_dir, 'src', 'test', 'fuzz', t),
+            os.path.join(test_dir, t),
             '-merge=1',
             # Also done by oss-fuzz
             # https://github.com/google/oss-fuzz/issues/1406#issuecomment-387790487
@@ -176,16 +187,23 @@
         ]
         os.makedirs(os.path.join(corpus, t), exist_ok=True)
         os.makedirs(os.path.join(merge_dir, t), exist_ok=True)
-        logging.debug('Run {} with args {}'.format(t, args))
-        output = subprocess.run(
-            args,
-            check=True,
-            stderr=subprocess.PIPE,
-            universal_newlines=True).stderr
-        logging.debug('Output: {}'.format(output))
+
+        def job(t, args):
+            output = 'Run {} with args {}\n'.format(t, " ".join(args))
+            output += subprocess.run(args,
+                                     check=True,
+                                     stderr=subprocess.PIPE,
+                                     universal_newlines=True).stderr
+            logging.debug(output)
+
+        jobs.append(fuzz_pool.submit(job, t, args))
+
+    for future in as_completed(jobs):
+        future.result()
 
 
-def run_once(*, corpus, test_list, test_dir, use_valgrind):
+def run_once(*, fuzz_pool, corpus, test_list, test_dir, use_valgrind):
+    jobs = []
     for t in test_list:
         corpus_path = os.path.join(corpus, t)
         os.makedirs(corpus_path, exist_ok=True)
@@ -199,13 +217,21 @@
                 'valgrind',
                 '--quiet',
                 '--error-exitcode=1'] + args
-        logging.debug('Run {} with args {}'.format(t, args))
-        result = subprocess.run(
-            args,
-            stderr=subprocess.PIPE,
-            universal_newlines=True)
-        output = result.stderr
-        logging.debug('Output: {}'.format(output))
+
+        def job(t, args):
+            output = 'Run {} with args {}'.format(t, args)
+            result = subprocess.run(
+                args,
+                stderr=subprocess.PIPE,
+                universal_newlines=True)
+            output += result.stderr
+            return output, result
+
+        jobs.append(fuzz_pool.submit(job, t, args))
+
+    for future in as_completed(jobs):
+        output, result = future.result()
+        logging.debug(output)
         try:
             result.check_returncode()
         except subprocess.CalledProcessError as e:
@@ -214,8 +240,10 @@
             if e.stderr:
                 logging.info(e.stderr)
             logging.info(
-                "Target \"{}\" failed with exit code {}: {}".format(
-                    t, e.returncode, " ".join(args)))
+                "Target \"{}\" failed with exit code {}".format(
+                    " ".join(
+                        result.args),
+                    e.returncode))
             sys.exit(1)