@@ -22,10 +22,14 @@ runners:
2222 os : ubuntu-24.04-16core-64gb
2323 << : *base-job
2424
25- - &job-macos
25+ - &job-macos-15
2626 os : macos-15 # macOS 15 Arm64
2727 << : *base-job
2828
29+ - &job-macos-26
30+ os : macos-26 # macOS 26 Arm64
31+ << : *base-job
32+
2933 - &job-windows
3034 os : windows-2025
3135 << : *base-job
@@ -476,7 +480,7 @@ auto:
476480 DEVELOPER_DIR : /Applications/Xcode_26.2.app/Contents/Developer
477481 DIST_REQUIRE_ALL_TOOLS : 1
478482 CODEGEN_BACKENDS : llvm,cranelift
479- << : *job-macos
483+ << : *job-macos-15
480484
481485 - name : dist-apple-various
482486 env :
@@ -513,7 +517,7 @@ auto:
513517 MACOSX_DEPLOYMENT_TARGET : 10.12
514518 MACOSX_STD_DEPLOYMENT_TARGET : 10.12
515519 DEVELOPER_DIR : /Applications/Xcode_26.2.app/Contents/Developer
516- << : *job-macos
520+ << : *job-macos-15
517521
518522 - name : dist-aarch64-apple
519523 env :
@@ -537,7 +541,7 @@ auto:
537541 DEVELOPER_DIR : /Applications/Xcode_26.2.app/Contents/Developer
538542 DIST_REQUIRE_ALL_TOOLS : 1
539543 CODEGEN_BACKENDS : llvm,cranelift
540- << : *job-macos
544+ << : *job-macos-15
541545
542546 - name : aarch64-apple
543547 env :
@@ -553,7 +557,29 @@ auto:
553557 # supports the hardware, so only need to test it there.
554558 MACOSX_DEPLOYMENT_TARGET : 11.0
555559 MACOSX_STD_DEPLOYMENT_TARGET : 11.0
556- << : *job-macos
560+ << : *job-macos-15
561+
562+ # EXPERIMENT(#157687): we will try to run `aarch64-apple`-equivalent workload
563+ # on `macos-26` runner images in parallel to evaluate the running times, since
564+ # previous attempts have timed out multiple times. Remove/revert this job if
565+ # this hangs or times out, or if it becomes the slowest Merge CI job, and let
566+ # T-infra know.
567+ - name : aarch64-apple-macos-26
568+ doc_url : https://github.com/rust-lang/rust/issues/157687
569+ env :
570+ SCRIPT : >
571+ ./x.py --stage 2 test --host=aarch64-apple-darwin --target=aarch64-apple-darwin &&
572+ ./x.py --stage 2 test --host=aarch64-apple-darwin --target=aarch64-apple-darwin src/tools/cargo
573+ RUST_CONFIGURE_ARGS : >-
574+ --enable-sanitizers
575+ --enable-profiler
576+ --set rust.jemalloc
577+ DEVELOPER_DIR : /Applications/Xcode_26.2.app/Contents/Developer
578+ # Aarch64 tooling only needs to support macOS 11.0 and up as nothing else
579+ # supports the hardware, so only need to test it there.
580+ MACOSX_DEPLOYMENT_TARGET : 11.0
581+ MACOSX_STD_DEPLOYMENT_TARGET : 11.0
582+ << : *job-macos-26
557583
558584 # #####################
559585 # Windows Builders #
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