diff --git a/doc/fuzzing.md b/doc/fuzzing.md
--- a/doc/fuzzing.md
+++ b/doc/fuzzing.md
@@ -48,15 +48,11 @@
 ```
 mkdir -p buildFuzzer
 cd buildFuzzer
-cmake -GNinja .. -DCCACHE=OFF -DCMAKE_C_COMPILER=afl-gcc -DCMAKE_CXX_COMPILER=afl-g++
+cmake -GNinja .. -DCMAKE_C_COMPILER=afl-gcc -DCMAKE_CXX_COMPILER=afl-g++
 export AFL_HARDEN=1
 ninja bitcoin-fuzzers
 ```
 
-We disable ccache because we don't want to pollute the ccache with instrumented
-objects, and similarly don't want to use non-instrumented cached objects linked
-in.
-
 The fuzzing can be sped up significantly (~200x) by using `afl-clang-fast` and
 `afl-clang-fast++` in place of `afl-gcc` and `afl-g++` when compiling. When
 compiling using `afl-clang-fast`/`afl-clang-fast++` the resulting
@@ -88,7 +84,6 @@
 mkdir -p buildFuzzer
 cd buildFuzzer
 cmake -GNinja .. \
-  -DCCACHE=OFF \
   -DCMAKE_C_COMPILER=clang \
   -DCMAKE_CXX_COMPILER=clang++ \
   -DENABLE_SANITIZERS="fuzzer;address;undefined"
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
@@ -15,7 +15,9 @@
 
 def main():
     parser = argparse.ArgumentParser(
-        formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter,
+        description='''Run the fuzz targets with all inputs from the seed_dir once.''',
+    )
     parser.add_argument(
         "-l",
         "--loglevel",
@@ -23,11 +25,6 @@
         default="INFO",
         help="log events at this level and higher to the console. Can be set to DEBUG, INFO, WARNING, ERROR or CRITICAL. Passing --loglevel DEBUG will output all logs to console.",
     )
-    parser.add_argument(
-        '--export_coverage',
-        action='store_true',
-        help='If true, export coverage information to files in the seed corpus',
-    )
     parser.add_argument(
         '--valgrind',
         action='store_true',
@@ -42,6 +39,10 @@
         nargs='*',
         help='The target(s) to run. Default is to run all targets.',
     )
+    parser.add_argument(
+        '--m_dir',
+        help='Merge inputs from this directory into the seed_dir. Needs /target subdirectory.',
+    )
 
     args = parser.parse_args()
 
@@ -122,16 +123,44 @@
             "subprocess timed out: Currently only libFuzzer is supported")
         sys.exit(1)
 
+    if args.m_dir:
+        merge_inputs(
+            corpus=args.seed_dir,
+            test_list=test_list_selection,
+            build_dir=config["environment"]["BUILDDIR"],
+            merge_dir=args.m_dir,
+        )
+
     run_once(
         corpus=args.seed_dir,
         test_list=test_list_selection,
         test_dir=test_dir,
-        export_coverage=args.export_coverage,
         use_valgrind=args.valgrind,
     )
 
 
-def run_once(*, corpus, test_list, test_dir, export_coverage, use_valgrind):
+def merge_inputs(*, corpus, test_list, build_dir, merge_dir):
+    logging.info(
+        "Merge the inputs in the passed dir into the seed_dir. Passed dir {}".format(merge_dir))
+    for t in test_list:
+        args = [
+            os.path.join(build_dir, 'src', 'test', 'fuzz', t),
+            '-merge=1',
+            os.path.join(corpus, t),
+            os.path.join(merge_dir, t),
+        ]
+        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 run_once(*, corpus, test_list, test_dir, use_valgrind):
     for t in test_list:
         corpus_path = os.path.join(corpus, t)
         os.makedirs(corpus_path, exist_ok=True)
@@ -155,13 +184,6 @@
         output = result.stderr
         logging.debug('Output: {}'.format(output))
         result.check_returncode()
-        if not export_coverage:
-            continue
-        for line in output.splitlines():
-            if 'INITED' in line:
-                with open(os.path.join(corpus, t + '_coverage'), 'w', encoding='utf-8') as cov_file:
-                    cov_file.write(line)
-                    break
 
 
 if __name__ == '__main__':