diff --git a/.gitignore b/.gitignore
index 2b8009b..9fd06f0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 /target
 .env
 /build
+/rust-project.json
diff --git a/AGENTS.md b/AGENTS.md
index 01fbd5e..5c8d35c 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -19,6 +19,7 @@ The project contains:
   entry helpers
 - `macros/src/lib.rs`: host-side `#[rslibc_macros::main]` attribute macro
 - `runtime/main.rs`: minimal example entry point
+- `cmake/RustLSP.cmake`: generates `rust-project.json` for rust-analyzer
 - `CMakeLists.txt`: direct `rustc` library, macro, and executable commands
 
 ## No-Std Design
@@ -112,6 +113,19 @@ Run it on Windows:
 - `RelWithDebInfo`: `-C opt-level=3 -C debuginfo=2`
 - Other or unset configurations: `-C opt-level=0 -C debuginfo=2`
 
+## LSP
+
+rust-analyzer works without Cargo through a generated manifest:
+
+- `cmake/RustLSP.cmake` runs on every configure and writes
+  `rust-project.json` (git-ignored) describing the three crates and the
+  toolchain sysroot, so `core`, `alloc`, and proc-macro attributes resolve.
+- Requires the rustup components:
+  `rustup component add rust-analyzer rust-src`.
+- Open the repository root in the editor so rust-analyzer picks up
+  `rust-project.json`. Re-run CMake configure after changing the crate
+  layout or switching toolchains.
+
 ## Verification
 
 After changing the source or build configuration, run a clean release build
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7d5e7f9..e269db0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,6 +4,9 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
 find_program(RUSTC rustc REQUIRED)
 
+# Generate rust-project.json for rust-analyzer (LSP) support.
+include(cmake/RustLSP.cmake)
+
 set(RUST_MACRO_SOURCE "${CMAKE_CURRENT_SOURCE_DIR}/macros/src/lib.rs")
 set(RUST_MACRO "${CMAKE_CURRENT_BINARY_DIR}/rslibc_macros${CMAKE_SHARED_LIBRARY_SUFFIX}")
 set(RUST_LIBRARY_SOURCE "${CMAKE_CURRENT_SOURCE_DIR}/src/lib.rs")
diff --git a/cmake/RustLSP.cmake b/cmake/RustLSP.cmake
new file mode 100644
index 0000000..f625a44
--- /dev/null
+++ b/cmake/RustLSP.cmake
@@ -0,0 +1,36 @@
+# Generate rust-project.json for rust-analyzer (LSP) support.
+#
+# This project has no Cargo manifest, so rust-analyzer cannot discover the
+# crate layout on its own. The generated file describes the three crates and
+# points at the toolchain sysroot so core/alloc resolve. It is regenerated on
+# every configure; the output is git-ignored.
+
+if(NOT RUSTC)
+    find_program(RUSTC rustc REQUIRED)
+endif()
+
+execute_process(
+    COMMAND "${RUSTC}" --print sysroot
+    OUTPUT_VARIABLE RUST_SYSROOT_RAW
+    RESULT_VARIABLE RUST_SYSROOT_RESULT
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+
+if(NOT RUST_SYSROOT_RESULT EQUAL 0 OR NOT RUST_SYSROOT_RAW)
+    message(FATAL_ERROR "Failed to query the rustc sysroot")
+endif()
+
+# Use forward slashes so the JSON needs no backslash escaping.
+string(REPLACE "\\" "/" RUST_SYSROOT "${RUST_SYSROOT_RAW}")
+set(RUST_SYSROOT_SRC "${RUST_SYSROOT}/lib/rustlib/src/rust/library")
+
+if(NOT IS_DIRECTORY "${RUST_SYSROOT_SRC}")
+    message(WARNING "rust-src not found at ${RUST_SYSROOT_SRC}. "
+        "Run `rustup component add rust-src` for full LSP support.")
+endif()
+
+configure_file(
+    "${CMAKE_CURRENT_LIST_DIR}/rust-project.json.in"
+    "${CMAKE_CURRENT_SOURCE_DIR}/rust-project.json"
+    @ONLY
+)
diff --git a/cmake/rust-project.json.in b/cmake/rust-project.json.in
new file mode 100644
index 0000000..c5217fc
--- /dev/null
+++ b/cmake/rust-project.json.in
@@ -0,0 +1,28 @@
+{
+    "sysroot": "@RUST_SYSROOT@",
+    "sysroot_src": "@RUST_SYSROOT_SRC@",
+    "crates": [
+        {
+            "display_name": "rslibc",
+            "root_module": "src/lib.rs",
+            "edition": "2021",
+            "deps": []
+        },
+        {
+            "display_name": "rslibc_macros",
+            "root_module": "macros/src/lib.rs",
+            "edition": "2021",
+            "is_proc_macro": true,
+            "deps": []
+        },
+        {
+            "display_name": "rslibc_example",
+            "root_module": "runtime/main.rs",
+            "edition": "2021",
+            "deps": [
+                { "crate": 0, "name": "rslibc" },
+                { "crate": 1, "name": "rslibc_macros" }
+            ]
+        }
+    ]
+}