diff --git a/projects/cli11/Dockerfile b/projects/cli11/Dockerfile
new file mode 100644
index 000000000000..c44c3c549540
--- /dev/null
+++ b/projects/cli11/Dockerfile
@@ -0,0 +1,19 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+FROM gcr.io/oss-fuzz-base/base-builder
+RUN apt-get update && apt-get install -y git && rm -rf /var/lib/apt/lists/*
+RUN git clone --depth=1 https://github.com/CLIUtils/CLI11.git $SRC/cli11
+COPY build.sh $SRC/
+WORKDIR $SRC
diff --git a/projects/cli11/build.sh b/projects/cli11/build.sh
new file mode 100755
index 000000000000..2ed3c254e194
--- /dev/null
+++ b/projects/cli11/build.sh
@@ -0,0 +1,30 @@
+#!/bin/bash -eu
+# Copyright 2025 Google LLC
+# Licensed under the Apache License, Version 2.0
+# See the License for the specific language governing permissions and
+# limitations under the License.
+set -o pipefail
+
+# --- Build the upstream CLI11 fuzz harness ---
+"$CXX" ${CXXFLAGS:-} -std=c++17 -I"$SRC/cli11/include" \
+  "$SRC/cli11/fuzz/cli11_app_fuzz.cpp" "$SRC/cli11/fuzz/fuzzApp.cpp" \
+  -o "$OUT/cli11_app_fuzzer" $LIB_FUZZING_ENGINE ${LDFLAGS:-}
+
+# --- Package dictionary (if present) ---
+if [[ -f "$SRC/cli11/fuzz/fuzz_dictionary1.txt" ]]; then
+  cp "$SRC/cli11/fuzz/fuzz_dictionary1.txt" "$OUT/cli11_app_fuzzer.dict" || true
+fi
+
+# --- Tiny, non-crashing seed corpus (zip + plain dir) ---
+seeddir=/tmp/cli11_seeds
+rm -rf "$seeddir" "$OUT/cli11_app_fuzzer_seed_corpus" || true
+mkdir -p "$seeddir" "$OUT/cli11_app_fuzzer_seed_corpus"
+
+: > "$seeddir/empty"               # zero-byte; must not crash
+printf -- '--help\n' > "$seeddir/help"
+
+# 1) Flat zip (no subdirectories) for libFuzzer/Honggfuzz
+zip -j -q "$OUT/cli11_app_fuzzer_seed_corpus.zip" "$seeddir/empty" "$seeddir/help"
+
+# 2) Plain directory for AFL++ (used by check_build)
+cp -f "$seeddir/empty" "$seeddir/help" "$OUT/cli11_app_fuzzer_seed_corpus/"
diff --git a/projects/cli11/project.yaml b/projects/cli11/project.yaml
new file mode 100644
index 000000000000..066777d3dc0b
--- /dev/null
+++ b/projects/cli11/project.yaml
@@ -0,0 +1,15 @@
+homepage: https://github.com/CLIUtils/CLI11
+main_repo: https://github.com/CLIUtils/CLI11
+language: c++
+fuzzing_engines:
+- honggfuzz
+- libfuzzer
+sanitizers:
+- address
+- undefined
+architectures:
+- i386
+- x86_64
+auto_ccs:
+- 140903820+TheodorNEngoy@users.noreply.github.com
+primary_contact: phlptp@gmail.com