diff --git a/Cargo.lock b/Cargo.lock
index 49c1eb5b45f77..3c999f4c598e2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -158,9 +158,9 @@ dependencies = [
 
 [[package]]
 name = "anyhow"
-version = "1.0.97"
+version = "1.0.98"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dcfed56ad506cb2c684a14971b8861fdc3baaaae314b9e5f9bb532cbe3ba7a4f"
+checksum = "e16d2d3311acee920a9eb8d33b8cbc1787ce4a264e85f964c2404b969bdcd487"
 dependencies = [
  "backtrace",
 ]
@@ -188,9 +188,9 @@ checksum = "7c02d123df017efcdfbd739ef81735b36c5ba83ec3c59c80a9d7ecc718f92e50"
 
 [[package]]
 name = "askama"
-version = "0.13.0"
+version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9a4e46abb203e00ef226442d452769233142bbfdd79c3941e84c8e61c4112543"
+checksum = "5d4744ed2eef2645831b441d8f5459689ade2ab27c854488fbab1fbe94fce1a7"
 dependencies = [
  "askama_derive",
  "itoa",
@@ -201,9 +201,9 @@ dependencies = [
 
 [[package]]
 name = "askama_derive"
-version = "0.13.0"
+version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "54398906821fd32c728135f7b351f0c7494ab95ae421d41b6f5a020e158f28a6"
+checksum = "d661e0f57be36a5c14c48f78d09011e67e0cb618f269cca9f2fd8d15b68c46ac"
 dependencies = [
  "askama_parser",
  "basic-toml",
@@ -225,7 +225,7 @@ dependencies = [
  "memchr",
  "serde",
  "serde_derive",
- "winnow 0.7.6",
+ "winnow 0.7.7",
 ]
 
 [[package]]
@@ -281,9 +281,9 @@ checksum = "5c8214115b7bf84099f1309324e63141d4c5d7cc26862f97a0a857dbefe165bd"
 
 [[package]]
 name = "blake3"
-version = "1.8.1"
+version = "1.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "389a099b34312839e16420d499a9cad9650541715937ffbdd40d36f49e77eeb3"
+checksum = "3888aaa89e4b2a40fca9848e400f6a658a5a3978de7be858e209cafa8be9a4a0"
 dependencies = [
  "arrayref",
  "arrayvec",
@@ -450,6 +450,11 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
 
+[[package]]
+name = "chili"
+version = "0.2.1"
+source = "git+https://github.com/zetanumbers/chili.git?branch=rustc#b0170bfb0020b5f7e22ee6d1fe9440015822b53f"
+
 [[package]]
 name = "chrono"
 version = "0.4.40"
@@ -496,9 +501,9 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.5.36"
+version = "4.5.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2df961d8c8a0d08aa9945718ccf584145eee3f3aa06cddbeac12933781102e04"
+checksum = "eccb054f56cbd38340b380d4a8e69ef1f02f1af43db2f0cc817a4774d80ae071"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -516,9 +521,9 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.5.36"
+version = "4.5.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "132dbda40fb6753878316a489d5a1242a8ef2f0d9e47ba01c951ea8aa7d013a5"
+checksum = "efd9466fac8543255d3b1fcad4762c5e116ffe808c8a3043d4263cd4fd4862a2"
 dependencies = [
  "anstream",
  "anstyle",
@@ -934,9 +939,9 @@ dependencies = [
 
 [[package]]
 name = "derive-where"
-version = "1.2.7"
+version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "62d671cc41a825ebabc75757b62d3d168c577f9149b2d49ece1dad1f72119d25"
+checksum = "2364b9aa47e460ce9bca6ac1777d14c98eef7e274eb077beed49f3adc94183ed"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1425,9 +1430,9 @@ dependencies = [
 
 [[package]]
 name = "getrandom"
-version = "0.2.15"
+version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
+checksum = "335ff9f135e4384c8150d6f27c6daed433577f86b4750418338c01a1a2528592"
 dependencies = [
  "cfg-if",
  "libc",
@@ -1910,9 +1915,9 @@ checksum = "4a5f13b858c8d314ee3e8f639011f7ccefe71f97f96e50151fb991f267928e2c"
 
 [[package]]
 name = "jiff"
-version = "0.2.6"
+version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1f33145a5cbea837164362c7bd596106eb7c5198f97d1ba6f6ebb3223952e488"
+checksum = "5a064218214dc6a10fbae5ec5fa888d80c45d611aba169222fc272072bf7aef6"
 dependencies = [
  "jiff-static",
  "log",
@@ -1923,9 +1928,9 @@ dependencies = [
 
 [[package]]
 name = "jiff-static"
-version = "0.2.6"
+version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "43ce13c40ec6956157a3635d97a1ee2df323b263f09ea14165131289cb0f5c19"
+checksum = "199b7932d97e325aff3a7030e141eafe7f2c6268e1d1b24859b753a627f45254"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2067,9 +2072,9 @@ dependencies = [
 
 [[package]]
 name = "libm"
-version = "0.2.11"
+version = "0.2.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8355be11b20d696c8f18f6cc018c4e372165b1fa8126cef092399c9951984ffa"
+checksum = "c9627da5196e5d8ed0b0495e61e518847578da83483c37288316d9b2e03a7f72"
 
 [[package]]
 name = "libredox"
@@ -2314,7 +2319,7 @@ dependencies = [
  "libffi",
  "libloading",
  "measureme",
- "rand 0.9.0",
+ "rand 0.9.1",
  "regex",
  "rustc_version",
  "smallvec",
@@ -2817,9 +2822,9 @@ checksum = "dc375e1527247fe1a97d8b7156678dfe7c1af2fc075c9a4db3690ecd2a148068"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.94"
+version = "1.0.95"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a31971752e70b8b2686d7e46ec17fb38dad4051d94024c88df49b667caea9c84"
+checksum = "02b3e5e68a3a1a02aad3ec490a98007cbc13c37cbe84a3cd7b8e406d76e7f778"
 dependencies = [
  "unicode-ident",
 ]
@@ -2902,13 +2907,12 @@ dependencies = [
 
 [[package]]
 name = "rand"
-version = "0.9.0"
+version = "0.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3779b94aeb87e8bd4e834cee3650289ee9e0d5677f976ecdb6d219e5f4f6cd94"
+checksum = "9fbfd9d094a40bf3ae768db9361049ace4c0e04a4fd6b359518bd7b73a73dd97"
 dependencies = [
  "rand_chacha 0.9.0",
  "rand_core 0.9.3",
- "zerocopy",
 ]
 
 [[package]]
@@ -2937,7 +2941,7 @@ version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
 dependencies = [
- "getrandom 0.2.15",
+ "getrandom 0.2.16",
 ]
 
 [[package]]
@@ -2993,7 +2997,7 @@ version = "0.4.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ba009ff324d1fc1b900bd1fdb31564febe58a8ccc8a6fdbb93b543d33b13ca43"
 dependencies = [
- "getrandom 0.2.15",
+ "getrandom 0.2.16",
  "libredox",
  "thiserror 1.0.69",
 ]
@@ -3004,7 +3008,7 @@ version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dd6f9d3d47bdd2ad6945c5015a226ec6155d0bcdfd8f7cd29f86b71f8de99d2b"
 dependencies = [
- "getrandom 0.2.15",
+ "getrandom 0.2.16",
  "libredox",
  "thiserror 2.0.12",
 ]
@@ -3186,16 +3190,6 @@ dependencies = [
  "tikv-jemalloc-sys",
 ]
 
-[[package]]
-name = "rustc-rayon-core"
-version = "0.5.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2f42932dcd3bcbe484b38a3ccf79b7906fac41c02d408b5b1bac26da3416efdb"
-dependencies = [
- "crossbeam-deque",
- "crossbeam-utils",
-]
-
 [[package]]
 name = "rustc-stable-hash"
 version = "0.1.2"
@@ -3219,7 +3213,7 @@ name = "rustc_abi"
 version = "0.0.0"
 dependencies = [
  "bitflags",
- "rand 0.9.0",
+ "rand 0.9.1",
  "rand_xoshiro",
  "rustc_data_structures",
  "rustc_hashes",
@@ -3543,6 +3537,7 @@ version = "0.0.0"
 dependencies = [
  "arrayvec",
  "bitflags",
+ "chili",
  "either",
  "elsa",
  "ena",
@@ -3555,7 +3550,6 @@ dependencies = [
  "parking_lot",
  "portable-atomic",
  "rustc-hash 2.1.1",
- "rustc-rayon-core",
  "rustc-stable-hash",
  "rustc_arena",
  "rustc_graphviz",
@@ -3842,7 +3836,7 @@ dependencies = [
 name = "rustc_incremental"
 version = "0.0.0"
 dependencies = [
- "rand 0.9.0",
+ "rand 0.9.1",
  "rustc_ast",
  "rustc_data_structures",
  "rustc_errors",
@@ -3901,7 +3895,7 @@ dependencies = [
 name = "rustc_interface"
 version = "0.0.0"
 dependencies = [
- "rustc-rayon-core",
+ "chili",
  "rustc_abi",
  "rustc_ast",
  "rustc_ast_lowering",
@@ -4061,10 +4055,10 @@ name = "rustc_middle"
 version = "0.0.0"
 dependencies = [
  "bitflags",
+ "chili",
  "either",
  "gsgdt",
  "polonius-engine",
- "rustc-rayon-core",
  "rustc_abi",
  "rustc_apfloat",
  "rustc_arena",
@@ -4326,9 +4320,9 @@ dependencies = [
 name = "rustc_query_system"
 version = "0.0.0"
 dependencies = [
+ "chili",
  "hashbrown",
  "parking_lot",
- "rustc-rayon-core",
  "rustc_abi",
  "rustc_ast",
  "rustc_attr_data_structures",
@@ -4410,7 +4404,7 @@ dependencies = [
  "bitflags",
  "getopts",
  "libc",
- "rand 0.9.0",
+ "rand 0.9.1",
  "rustc_abi",
  "rustc_ast",
  "rustc_data_structures",
@@ -4956,15 +4950,6 @@ dependencies = [
  "color-eyre",
 ]
 
-[[package]]
-name = "spdx"
-version = "0.10.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "58b69356da67e2fc1f542c71ea7e654a361a79c938e4424392ecf4fa065d2193"
-dependencies = [
- "smallvec",
-]
-
 [[package]]
 name = "spdx-expression"
 version = "0.5.2"
@@ -5209,7 +5194,7 @@ version = "0.1.0"
 dependencies = [
  "indicatif",
  "num",
- "rand 0.9.0",
+ "rand 0.9.1",
  "rand_chacha 0.9.0",
  "rayon",
 ]
@@ -5784,9 +5769,9 @@ dependencies = [
 
 [[package]]
 name = "wasi-preview1-component-adapter-provider"
-version = "29.0.1"
+version = "31.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dcd9f21bbde82ba59e415a8725e6ad0d0d7e9e460b1a3ccbca5bdee952c1a324"
+checksum = "86fabda09a0d89ffd1615b297b4a5d4b4d99df9598aeb24685837e63019e927b"
 
 [[package]]
 name = "wasm-bindgen"
@@ -5848,9 +5833,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-component-ld"
-version = "0.5.12"
+version = "0.5.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "580305a8e3f1b7a79859a8db897de643533b2851c5eb080fe5800233f16dec88"
+checksum = "a60a07a994a3538b57d8c5f8caba19f4793fb4c7156276e5e90e90acbb829e20"
 dependencies = [
  "anyhow",
  "clap",
@@ -5858,7 +5843,7 @@ dependencies = [
  "libc",
  "tempfile",
  "wasi-preview1-component-adapter-provider",
- "wasmparser 0.223.1",
+ "wasmparser 0.229.0",
  "wat",
  "windows-sys 0.59.0",
  "winsplit",
@@ -5885,39 +5870,24 @@ dependencies = [
 
 [[package]]
 name = "wasm-encoder"
-version = "0.223.1"
+version = "0.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a0a96fdeaee8fbeb4bd917fb8157d48c0d61c3b1f4ee4c363c8e8d68b2f4fe8"
-dependencies = [
- "leb128",
- "wasmparser 0.223.1",
-]
-
-[[package]]
-name = "wasm-encoder"
-version = "0.228.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "05d30290541f2d4242a162bbda76b8f2d8b1ac59eab3568ed6f2327d52c9b2c4"
+checksum = "38ba1d491ecacb085a2552025c10a675a6fddcbd03b1fc9b36c536010ce265d2"
 dependencies = [
  "leb128fmt",
- "wasmparser 0.228.0",
+ "wasmparser 0.229.0",
 ]
 
 [[package]]
 name = "wasm-metadata"
-version = "0.223.1"
+version = "0.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e2e7e37883181704d96b89dbd8f1291be13694c71cd0663aebb94b46d235a377"
+checksum = "78fdb7d29a79191ab363dc90c1ddd3a1e880ffd5348d92d48482393a9e6c5f4d"
 dependencies = [
  "anyhow",
  "indexmap",
- "serde",
- "serde_derive",
- "serde_json",
- "spdx",
- "url",
- "wasm-encoder 0.223.1",
- "wasmparser 0.223.1",
+ "wasm-encoder 0.229.0",
+ "wasmparser 0.229.0",
 ]
 
 [[package]]
@@ -5941,9 +5911,9 @@ dependencies = [
 
 [[package]]
 name = "wasmparser"
-version = "0.223.1"
+version = "0.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "664b980991ed9a8c834eb528a8979ab1109edcf52dc05dd5751e2cc3fb31035d"
+checksum = "0cc3b1f053f5d41aa55640a1fa9b6d1b8a9e4418d118ce308d20e24ff3575a8c"
 dependencies = [
  "bitflags",
  "hashbrown",
@@ -5952,35 +5922,24 @@ dependencies = [
  "serde",
 ]
 
-[[package]]
-name = "wasmparser"
-version = "0.228.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4abf1132c1fdf747d56bbc1bb52152400c70f336870f968b85e89ea422198ae3"
-dependencies = [
- "bitflags",
- "indexmap",
- "semver",
-]
-
 [[package]]
 name = "wast"
-version = "228.0.0"
+version = "229.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e5aae124478cb51439f6587f074a3a5e835afd22751c59a87b2e2a882727c97"
+checksum = "63fcaff613c12225696bb163f79ca38ffb40e9300eff0ff4b8aa8b2f7eadf0d9"
 dependencies = [
  "bumpalo",
  "leb128fmt",
  "memchr",
  "unicode-width 0.2.0",
- "wasm-encoder 0.228.0",
+ "wasm-encoder 0.229.0",
 ]
 
 [[package]]
 name = "wat"
-version = "1.228.0"
+version = "1.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7ec29c89a8d055df988de7236483bf569988ac3d6905899f6af5ef920f9385ad"
+checksum = "4189bad08b70455a9e9e67dc126d2dcf91fac143a80f1046747a5dde6d4c33e0"
 dependencies = [
  "wast",
 ]
@@ -6415,9 +6374,9 @@ dependencies = [
 
 [[package]]
 name = "winnow"
-version = "0.7.6"
+version = "0.7.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "63d3fcd9bba44b03821e7d699eeee959f3126dcc4aa8e4ae18ec617c2a5cea10"
+checksum = "6cb8234a863ea0e8cd7284fcdd4f145233eb00fee02bbdd9861aec44e6477bc5"
 dependencies = [
  "memchr",
 ]
@@ -6439,9 +6398,9 @@ dependencies = [
 
 [[package]]
 name = "wit-component"
-version = "0.223.1"
+version = "0.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3fc2fcc52a79f6f010a89c867e53e06d4227f86c58984add3e37f32b8e7af5f0"
+checksum = "7f550067740e223bfe6c4878998e81cdbe2529dd9a793dc49248dd6613394e8b"
 dependencies = [
  "anyhow",
  "bitflags",
@@ -6450,17 +6409,17 @@ dependencies = [
  "serde",
  "serde_derive",
  "serde_json",
- "wasm-encoder 0.223.1",
+ "wasm-encoder 0.229.0",
  "wasm-metadata",
- "wasmparser 0.223.1",
+ "wasmparser 0.229.0",
  "wit-parser",
 ]
 
 [[package]]
 name = "wit-parser"
-version = "0.223.1"
+version = "0.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "263fde17f1fbe55a413f16eb59094bf751795c6da469a05c3d45ea6c77df6b40"
+checksum = "459c6ba62bf511d6b5f2a845a2a736822e38059c1cfa0b644b467bbbfae4efa6"
 dependencies = [
  "anyhow",
  "id-arena",
@@ -6471,7 +6430,7 @@ dependencies = [
  "serde_derive",
  "serde_json",
  "unicode-xid",
- "wasmparser 0.223.1",
+ "wasmparser 0.229.0",
 ]
 
 [[package]]
diff --git a/compiler/rustc_data_structures/Cargo.toml b/compiler/rustc_data_structures/Cargo.toml
index f48c73b13b961..b49e1b5450849 100644
--- a/compiler/rustc_data_structures/Cargo.toml
+++ b/compiler/rustc_data_structures/Cargo.toml
@@ -14,7 +14,7 @@ indexmap = "2.4.0"
 jobserver_crate = { version = "0.1.28", package = "jobserver" }
 measureme = "12.0.1"
 rustc-hash = "2.0.0"
-rustc-rayon-core = { version = "0.5.0" }
+chili = { git = "https://github.com/zetanumbers/chili.git", branch = "rustc" }
 rustc-stable-hash = { version = "0.1.0", features = ["nightly"] }
 rustc_arena = { path = "../rustc_arena" }
 rustc_graphviz = { path = "../rustc_graphviz" }
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index 616a18a72ab7e..1284166f9e4e5 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -43,7 +43,7 @@ pub use self::freeze::{FreezeLock, FreezeReadGuard, FreezeWriteGuard};
 pub use self::lock::{Lock, LockGuard, Mode};
 pub use self::mode::{is_dyn_thread_safe, set_dyn_thread_safe_mode};
 pub use self::parallel::{
-    join, par_for_each_in, par_map, parallel_guard, scope, try_par_for_each_in,
+    join, join4, par_for_each_in, par_map, parallel_guard, try_par_for_each_in,
 };
 pub use self::vec::{AppendOnlyIndexVec, AppendOnlyVec};
 pub use self::worker_local::{Registry, WorkerLocal};
diff --git a/compiler/rustc_data_structures/src/sync/parallel.rs b/compiler/rustc_data_structures/src/sync/parallel.rs
index ba3c85ef5b155..af2623b702fd4 100644
--- a/compiler/rustc_data_structures/src/sync/parallel.rs
+++ b/compiler/rustc_data_structures/src/sync/parallel.rs
@@ -58,49 +58,58 @@ where
     (a.unwrap(), b.unwrap())
 }
 
-/// Runs a list of blocks in parallel. The first block is executed immediately on
-/// the current thread. Use that for the longest running block.
-#[macro_export]
-macro_rules! parallel {
-        (impl $fblock:block [$($c:expr,)*] [$block:expr $(, $rest:expr)*]) => {
-            parallel!(impl $fblock [$block, $($c,)*] [$($rest),*])
-        };
-        (impl $fblock:block [$($blocks:expr,)*] []) => {
-            $crate::sync::parallel_guard(|guard| {
-                $crate::sync::scope(|s| {
-                    $(
-                        let block = $crate::sync::FromDyn::from(|| $blocks);
-                        s.spawn(move |_| {
-                            guard.run(move || block.into_inner()());
-                        });
-                    )*
-                    guard.run(|| $fblock);
-                });
-            });
-        };
-        ($fblock:block, $($blocks:block),*) => {
-            if $crate::sync::is_dyn_thread_safe() {
-                // Reverse the order of the later blocks since Rayon executes them in reverse order
-                // when using a single thread. This ensures the execution order matches that
-                // of a single threaded rustc.
-                parallel!(impl $fblock [] [$($blocks),*]);
-            } else {
-                $crate::sync::parallel_guard(|guard| {
-                    guard.run(|| $fblock);
-                    $(guard.run(|| $blocks);)*
-                });
-            }
-        };
-    }
-
-// This function only works when `mode::is_dyn_thread_safe()`.
-pub fn scope<'scope, OP, R>(op: OP) -> R
+pub fn join4<F0, F1, F2, F3, R0, R1, R2, R3>(
+    oper0: F0,
+    oper1: F1,
+    oper2: F2,
+    oper3: F3,
+) -> (R0, R1, R2, R3)
 where
-    OP: FnOnce(&rayon_core::Scope<'scope>) -> R + DynSend,
-    R: DynSend,
+    F0: FnOnce() -> R0 + DynSend,
+    F1: FnOnce() -> R1 + DynSend,
+    F2: FnOnce() -> R2 + DynSend,
+    F3: FnOnce() -> R3 + DynSend,
+    R0: DynSend,
+    R1: DynSend,
+    R2: DynSend,
+    R3: DynSend,
 {
-    let op = FromDyn::from(op);
-    rayon_core::scope(|s| FromDyn::from(op.into_inner()(s))).into_inner()
+    if mode::is_dyn_thread_safe() {
+        let oper0 = FromDyn::from(oper0);
+        let oper1 = FromDyn::from(oper1);
+        let oper2 = FromDyn::from(oper2);
+        let oper3 = FromDyn::from(oper3);
+        // Swap closures around because Chili executes second one on the current thread
+        let (r1, (r2, (r3, r0))) = parallel_guard(|guard| {
+            chili::Scope::with_current(|scope| {
+                scope.unwrap().join_with_heartbeat_every::<1, _, _, _, _>(
+                    move |_| guard.run(move || FromDyn::from(oper1.into_inner()())),
+                    move |scope| {
+                        scope.join_with_heartbeat_every::<1, _, _, _, _>(
+                            move |_| guard.run(move || FromDyn::from(oper2.into_inner()())),
+                            move |scope| {
+                                scope.join_with_heartbeat_every::<1, _, _, _, _>(
+                                    move |_| guard.run(move || FromDyn::from(oper3.into_inner()())),
+                                    move |_| guard.run(move || FromDyn::from(oper0.into_inner()())),
+                                )
+                            },
+                        )
+                    },
+                )
+            })
+        });
+        (
+            r0.unwrap().into_inner(),
+            r1.unwrap().into_inner(),
+            r2.unwrap().into_inner(),
+            r3.unwrap().into_inner(),
+        )
+    } else {
+        let (r0, r1, r2, r3) = parallel_guard(|guard| {
+            (guard.run(oper0), guard.run(oper1), guard.run(oper2), guard.run(oper3))
+        });
+        (r0.unwrap(), r1.unwrap(), r2.unwrap(), r3.unwrap())
+    }
 }
 
 #[inline]
@@ -112,11 +121,14 @@ where
     if mode::is_dyn_thread_safe() {
         let oper_a = FromDyn::from(oper_a);
         let oper_b = FromDyn::from(oper_b);
-        let (a, b) = parallel_guard(|guard| {
-            rayon_core::join(
-                move || guard.run(move || FromDyn::from(oper_a.into_inner()())),
-                move || guard.run(move || FromDyn::from(oper_b.into_inner()())),
-            )
+        let (b, a) = parallel_guard(|guard| {
+            chili::Scope::with_current(|scope| {
+                scope.unwrap().join_with_heartbeat_every::<1, _, _, _, _>(
+                    // Swap arguments around because Chili executes second one on the current thread
+                    move |_| guard.run(move || FromDyn::from(oper_b.into_inner()())),
+                    move |_| guard.run(move || FromDyn::from(oper_a.into_inner()())),
+                )
+            })
         });
         (a.unwrap().into_inner(), b.unwrap().into_inner())
     } else {
@@ -136,6 +148,7 @@ fn par_slice<I: DynSend>(
     }
 
     fn par_rec<I: DynSend, F: Fn(&mut I) + DynSync + DynSend>(
+        scope: &mut chili::Scope<'_>,
         items: &mut [I],
         state: &State<'_, F>,
     ) {
@@ -147,7 +160,11 @@ fn par_slice<I: DynSend>(
             let (left, right) = items.split_at_mut(items.len() / 2);
             let mut left = state.for_each.derive(left);
             let mut right = state.for_each.derive(right);
-            rayon_core::join(move || par_rec(*left, state), move || par_rec(*right, state));
+            scope.join(
+                // Swap arguments around because Chili executes second one on the current thread
+                move |scope| par_rec(scope, *right, state),
+                move |scope| par_rec(scope, *left, state),
+            );
         }
     }
 
@@ -156,7 +173,7 @@ fn par_slice<I: DynSend>(
         guard,
         group: std::cmp::max(items.len() / 128, 1),
     };
-    par_rec(items, &state)
+    chili::Scope::with_current(|scope| par_rec(&mut scope.unwrap(), items, &state));
 }
 
 pub fn par_for_each_in<I: DynSend, T: IntoIterator<Item = I>>(
diff --git a/compiler/rustc_interface/Cargo.toml b/compiler/rustc_interface/Cargo.toml
index ff28dbeaee698..9912acc0504ab 100644
--- a/compiler/rustc_interface/Cargo.toml
+++ b/compiler/rustc_interface/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-rustc-rayon-core = { version = "0.5.0" }
+chili = { git = "https://github.com/zetanumbers/chili.git", branch = "rustc" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_ast_lowering = { path = "../rustc_ast_lowering" }
 rustc_ast_passes = { path = "../rustc_ast_passes" }
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index fde1872fb399e..25958ab70802f 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -7,9 +7,8 @@ use std::{env, fs, iter};
 
 use rustc_ast as ast;
 use rustc_codegen_ssa::traits::CodegenBackend;
-use rustc_data_structures::parallel;
 use rustc_data_structures::steal::Steal;
-use rustc_data_structures::sync::{AppendOnlyIndexVec, FreezeLock, WorkerLocal};
+use rustc_data_structures::sync::{AppendOnlyIndexVec, FreezeLock, WorkerLocal, join, join4};
 use rustc_expand::base::{ExtCtxt, LintStoreExpand};
 use rustc_feature::Features;
 use rustc_fs_util::try_canonicalize;
@@ -902,8 +901,8 @@ fn run_required_analyses(tcx: TyCtxt<'_>) {
     rustc_passes::hir_id_validator::check_crate(tcx);
     let sess = tcx.sess;
     sess.time("misc_checking_1", || {
-        parallel!(
-            {
+        join4(
+            || {
                 sess.time("looking_for_entry_point", || tcx.ensure_ok().entry_fn(()));
 
                 sess.time("looking_for_derive_registrar", || {
@@ -912,7 +911,7 @@ fn run_required_analyses(tcx: TyCtxt<'_>) {
 
                 CStore::from_tcx(tcx).report_unused_deps(tcx);
             },
-            {
+            || {
                 tcx.par_hir_for_each_module(|module| {
                     tcx.ensure_ok().check_mod_loops(module);
                     tcx.ensure_ok().check_mod_attrs(module);
@@ -920,19 +919,19 @@ fn run_required_analyses(tcx: TyCtxt<'_>) {
                     tcx.ensure_ok().check_mod_unstable_api_usage(module);
                 });
             },
-            {
+            || {
                 sess.time("unused_lib_feature_checking", || {
                     rustc_passes::stability::check_unused_or_stable_features(tcx)
                 });
             },
-            {
+            || {
                 // We force these queries to run,
                 // since they might not otherwise get called.
                 // This marks the corresponding crate-level attributes
                 // as used, and ensures that their values are valid.
                 tcx.ensure_ok().limits(());
                 tcx.ensure_ok().stability_index(());
-            }
+            },
         );
     });
 
@@ -1027,36 +1026,36 @@ fn analysis(tcx: TyCtxt<'_>, (): ()) {
     }
 
     sess.time("misc_checking_3", || {
-        parallel!(
-            {
+        join(
+            || {
                 tcx.ensure_ok().effective_visibilities(());
 
-                parallel!(
-                    {
+                join4(
+                    || {
                         tcx.ensure_ok().check_private_in_public(());
                     },
-                    {
+                    || {
                         tcx.par_hir_for_each_module(|module| {
                             tcx.ensure_ok().check_mod_deathness(module)
                         });
                     },
-                    {
+                    || {
                         sess.time("lint_checking", || {
                             rustc_lint::check_crate(tcx);
                         });
                     },
-                    {
+                    || {
                         tcx.ensure_ok().clashing_extern_declarations(());
-                    }
+                    },
                 );
             },
-            {
+            || {
                 sess.time("privacy_checking_modules", || {
                     tcx.par_hir_for_each_module(|module| {
                         tcx.ensure_ok().check_mod_privacy(module);
                     });
                 });
-            }
+            },
         );
 
         // This check has to be run after all lints are done processing. We don't
diff --git a/compiler/rustc_interface/src/util.rs b/compiler/rustc_interface/src/util.rs
index c3a939f1ab086..1dc52e1796428 100644
--- a/compiler/rustc_interface/src/util.rs
+++ b/compiler/rustc_interface/src/util.rs
@@ -1,4 +1,5 @@
 use std::env::consts::{DLL_PREFIX, DLL_SUFFIX};
+use std::num::NonZero;
 use std::path::{Path, PathBuf};
 use std::sync::OnceLock;
 use std::sync::atomic::{AtomicBool, Ordering};
@@ -190,17 +191,17 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send,
     let current_gcx = FromDyn::from(CurrentGcx::new());
     let current_gcx2 = current_gcx.clone();
 
-    let builder = rayon_core::ThreadPoolBuilder::new()
-        .thread_name(|_| "rustc".to_string())
-        .acquire_thread_handler(jobserver::acquire_thread)
-        .release_thread_handler(jobserver::release_thread)
-        .num_threads(threads)
-        .deadlock_handler(move || {
+    let config = chili::Config {
+        // .thread_name(|_| "rustc".to_string())
+        acquire_thread_handler: Some(Box::new(jobserver::acquire_thread)),
+        release_thread_handler: Some(Box::new(jobserver::release_thread)),
+        thread_count: NonZero::new(threads),
+        stack_size: NonZero::new(thread_stack_size),
+        deadlock_handler: Some(Box::new(move || {
             // On deadlock, creates a new thread and forwards information in thread
             // locals to it. The new thread runs the deadlock handler.
 
             let current_gcx2 = current_gcx2.clone();
-            let registry = rayon_core::Registry::current();
             let session_globals = rustc_span::with_session_globals(|session_globals| {
                 session_globals as *const SessionGlobals as usize
             });
@@ -226,7 +227,7 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send,
                                     // We need the complete map to ensure we find a cycle to break.
                                     QueryCtxt::new(tcx).collect_active_jobs().ok().expect("failed to collect active queries in deadlock handler")
                                 });
-                                break_query_cycles(query_map, &registry);
+                                break_query_cycles(query_map);
                             })
                         })
                     });
@@ -234,8 +235,11 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send,
                     on_panic.disable();
                 })
                 .unwrap();
-        })
-        .stack_size(thread_stack_size);
+        })),
+        // TODO: Tune heartbeat_interval
+        // heartbeat_interval: Duration::from_micros(100),
+        ..Default::default()
+    };
 
     // We create the session globals on the main thread, then create the thread
     // pool. Upon creation, each worker thread created gets a copy of the
@@ -244,23 +248,25 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send,
     rustc_span::create_session_globals_then(edition, extra_symbols, Some(sm_inputs), || {
         rustc_span::with_session_globals(|session_globals| {
             let session_globals = FromDyn::from(session_globals);
-            builder
-                .build_scoped(
-                    // Initialize each new worker thread when created.
-                    move |thread: rayon_core::ThreadBuilder| {
-                        // Register the thread for use with the `WorkerLocal` type.
-                        registry.register();
-
-                        rustc_span::set_session_globals_then(session_globals.into_inner(), || {
-                            thread.run()
-                        })
-                    },
-                    // Run `f` on the first thread in the thread pool.
-                    move |pool: &rayon_core::ThreadPool| {
-                        pool.install(|| f(current_gcx.into_inner()))
-                    },
-                )
-                .unwrap()
+            chili::ThreadPool::scoped_global(
+                config,
+                // Initialize each new worker thread when created.
+                move |thread: chili::ThreadBuilder| {
+                    // Register the thread for use with the `WorkerLocal` type.
+                    registry.register();
+
+                    rustc_span::set_session_globals_then(session_globals.into_inner(), || {
+                        thread.run()
+                    })
+                },
+                // Run `f` on the first thread in the thread pool.
+                move || {
+                    chili::Scope::with_current(|scope| {
+                        scope.unwrap().install(|_| f(current_gcx.into_inner()))
+                    })
+                },
+            )
+            .unwrap()
         })
     })
 }
diff --git a/compiler/rustc_middle/Cargo.toml b/compiler/rustc_middle/Cargo.toml
index 43c1af642dd56..4d166094d7c7d 100644
--- a/compiler/rustc_middle/Cargo.toml
+++ b/compiler/rustc_middle/Cargo.toml
@@ -9,7 +9,7 @@ bitflags = "2.4.1"
 either = "1.5.0"
 gsgdt = "0.1.2"
 polonius-engine = "0.13.0"
-rustc-rayon-core = { version = "0.5.0" }
+chili = { git = "https://github.com/zetanumbers/chili.git", branch = "rustc" }
 rustc_abi = { path = "../rustc_abi" }
 rustc_apfloat = "0.2.0"
 rustc_arena = { path = "../rustc_arena" }
diff --git a/compiler/rustc_middle/src/ty/context/tls.rs b/compiler/rustc_middle/src/ty/context/tls.rs
index 5fc80bc793673..6d5bce448e9a6 100644
--- a/compiler/rustc_middle/src/ty/context/tls.rs
+++ b/compiler/rustc_middle/src/ty/context/tls.rs
@@ -36,7 +36,7 @@ impl<'a, 'tcx> ImplicitCtxt<'a, 'tcx> {
 }
 
 // Import the thread-local variable from Rayon, which is preserved for Rayon jobs.
-use rayon_core::tlv::TLV;
+use chili::tlv::TLV;
 
 #[inline]
 fn erase(context: &ImplicitCtxt<'_, '_>) -> *const () {
diff --git a/compiler/rustc_query_system/Cargo.toml b/compiler/rustc_query_system/Cargo.toml
index 7db06953aeb64..a7680c8898a7c 100644
--- a/compiler/rustc_query_system/Cargo.toml
+++ b/compiler/rustc_query_system/Cargo.toml
@@ -6,7 +6,7 @@ edition = "2024"
 [dependencies]
 # tidy-alphabetical-start
 parking_lot = "0.12"
-rustc-rayon-core = { version = "0.5.0" }
+chili = { git = "https://github.com/zetanumbers/chili.git", branch = "rustc" }
 rustc_abi = { path = "../rustc_abi" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_attr_data_structures = { path = "../rustc_attr_data_structures" }
diff --git a/compiler/rustc_query_system/src/query/job.rs b/compiler/rustc_query_system/src/query/job.rs
index de35cd79ea275..e98c1a922b1d8 100644
--- a/compiler/rustc_query_system/src/query/job.rs
+++ b/compiler/rustc_query_system/src/query/job.rs
@@ -236,7 +236,7 @@ impl<I> QueryLatch<I> {
             // If this detects a deadlock and the deadlock handler wants to resume this thread
             // we have to be in the `wait` call. This is ensured by the deadlock handler
             // getting the self.info lock.
-            rayon_core::mark_blocked();
+            chili::mark_blocked().unwrap();
             jobserver::release_thread();
             waiter.condvar.wait(&mut info);
             // Release the lock before we potentially block in `acquire_thread`
@@ -250,9 +250,8 @@ impl<I> QueryLatch<I> {
         let mut info = self.info.lock();
         debug_assert!(!info.complete);
         info.complete = true;
-        let registry = rayon_core::Registry::current();
         for waiter in info.waiters.drain(..) {
-            rayon_core::mark_unblocked(&registry);
+            chili::mark_unblocked().unwrap();
             waiter.condvar.notify_one();
         }
     }
@@ -504,10 +503,7 @@ fn remove_cycle<I: Clone>(
 /// uses a query latch and then resuming that waiter.
 /// There may be multiple cycles involved in a deadlock, so this searches
 /// all active queries for cycles before finally resuming all the waiters at once.
-pub fn break_query_cycles<I: Clone + Debug>(
-    query_map: QueryMap<I>,
-    registry: &rayon_core::Registry,
-) {
+pub fn break_query_cycles<I: Clone + Debug>(query_map: QueryMap<I>) {
     let mut wakelist = Vec::new();
     let mut jobs: Vec<QueryJobId> = query_map.keys().cloned().collect();
 
@@ -538,7 +534,7 @@ pub fn break_query_cycles<I: Clone + Debug>(
     // we wake the threads up as otherwise Rayon could detect a deadlock if a thread we
     // resumed fell asleep and this thread had yet to mark the remaining threads as unblocked.
     for _ in 0..wakelist.len() {
-        rayon_core::mark_unblocked(registry);
+        chili::mark_unblocked().unwrap();
     }
 
     for waiter in wakelist.into_iter() {