diff --git a/.buildkite/Dockerfile b/.buildkite/Dockerfile
index 36fb1b0215..3ebf711c28 100644
--- a/.buildkite/Dockerfile
+++ b/.buildkite/Dockerfile
@@ -189,12 +189,12 @@ RUN git clone --depth=1 https://github.com/oven-sh/bun.git /var/lib/buildkite-ag
 WORKDIR /var/lib/buildkite-agent/build
 
 # Install dependencies, generate source lists, and run cmake configure to download build dependencies
+# Keep cmake/ninja files so subsequent builds can skip already-downloaded dependencies
 RUN bun install --frozen-lockfile && \
     bun run scripts/glob-sources.mjs && \
     mkdir -p build/release && \
     cmake -S . -B build/release -G Ninja -DCMAKE_BUILD_TYPE=Release -DCI=ON && \
     cmake --build build/release --target clone-zig clone-boringssl clone-mimalloc clone-zstd clone-lolhtml clone-cares clone-libdeflate clone-libarchive clone-tinycc clone-zlib clone-lshpack clone-brotli clone-highway clone-hdrhistogram clone-picohttpparser || true && \
-    rm -rf build/release/CMakeFiles build/release/CMakeCache.txt build/release/cmake_install.cmake build/release/build.ninja build/release/compile_commands.json && \
     rm -rf node_modules
 
 COPY  ../*/agent.mjs /var/bun/scripts/
diff --git a/scripts/bake-dependencies.sh b/scripts/bake-dependencies.sh
index d218b3f466..6798b34091 100755
--- a/scripts/bake-dependencies.sh
+++ b/scripts/bake-dependencies.sh
@@ -122,10 +122,9 @@ cmake --build "$BUILD_PATH" --target clone-zig clone-boringssl clone-mimalloc cl
 print "Downloading debug WebKit variant..."
 cmake $CMAKE_ARGS -DCMAKE_BUILD_TYPE=Debug -B "$BUN_REPO_PATH/build/debug" || true
 
-# Clean up build artifacts but keep downloaded dependencies
-print "Cleaning up build artifacts..."
-rm -rf "$BUILD_PATH/CMakeFiles" "$BUILD_PATH/CMakeCache.txt" "$BUILD_PATH/cmake_install.cmake" "$BUILD_PATH/build.ninja" "$BUILD_PATH/compile_commands.json" "$BUILD_PATH/.ninja_deps" "$BUILD_PATH/.ninja_log"
-rm -rf "$BUN_REPO_PATH/build/debug/CMakeFiles" "$BUN_REPO_PATH/build/debug/CMakeCache.txt" "$BUN_REPO_PATH/build/debug/build.ninja" 2>/dev/null || true
+# Keep cmake/ninja files so subsequent builds don't re-download dependencies
+# The ninja build system tracks what's been built - removing these files causes re-downloads
+print "Keeping build system files for caching..."
 
 # Remove node_modules - will be reinstalled during actual builds
 print "Removing node_modules..."