diff --git a/.github/actions/build-with-patched-std/action.yml b/.github/actions/build-with-patched-std/action.yml
deleted file mode 100644
index 46edb7ee..00000000
--- a/.github/actions/build-with-patched-std/action.yml
+++ /dev/null
@@ -1,50 +0,0 @@
-# Github composite action to build a single-source-file test binary with an
-# already-checked-out version of Rust's stdlib, that will be patched with a
-# given revision of the backtrace crate.
-
-name: Build with patched std
-description: >
-  Build a binary with a version of std that's had a specific revision of
-  backtrace patched in.
-inputs:
-  backtrace-commit:
-    description: The git commit of backtrace to patch in to std
-    required: true
-  main-rs:
-    description: The (single) source code file to compile
-    required: true
-  rustc-dir:
-    description: The root directory of the rustc repo
-    required: true
-outputs:
-  test-binary-size:
-    description: The size in bytes of the built test binary
-    value: ${{ steps.measure.outputs.test-binary-size }}
-runs:
-  using: composite
-  steps:
-    - shell: bash
-      id: measure
-      env:
-        RUSTC_FLAGS: -Copt-level=3 -Cstrip=symbols
-        # This symlink is made by Build::new() in the bootstrap crate, using a
-        # symlink on Linux and a junction on Windows, so it will exist on both
-        # platforms.
-        RUSTC_BUILD_DIR: build/host
-        RUST_BACKTRACE: 1
-      working-directory: ${{ inputs.rustc-dir }}
-      run: |
-        set -x
-        rm -rf "$RUSTC_BUILD_DIR/stage0-std"
-
-        (cd library/backtrace && git checkout ${{ inputs.backtrace-commit }})
-        git add library/backtrace
-
-        python3 x.py build library --stage 0
-
-        TEMP_BUILD_OUTPUT=$(mktemp test-binary-XXXXXXXX)
-        "$RUSTC_BUILD_DIR/stage0-sysroot/bin/rustc" $RUSTC_FLAGS "${{ inputs.main-rs }}" -o "$TEMP_BUILD_OUTPUT"
-        BINARY_SIZE=$(stat -c '%s' "$TEMP_BUILD_OUTPUT")
-        rm "$TEMP_BUILD_OUTPUT"
-
-        echo "test-binary-size=$BINARY_SIZE" >> "$GITHUB_OUTPUT"
diff --git a/.github/actions/report-code-size-changes/action.yml b/.github/actions/report-code-size-changes/action.yml
deleted file mode 100644
index ede26975..00000000
--- a/.github/actions/report-code-size-changes/action.yml
+++ /dev/null
@@ -1,111 +0,0 @@
-# Github composite action to report on code size changes across different
-# platforms.
-
-name: Report binary size changes on PR
-description: |
-  Report on code size changes across different platforms resulting from a PR.
-  The only input argument is the path to a directory containing a set of
-  "*.json" files (extension required), each file containing the keys:
-
-   - platform: the platform that the code size change was measured on
-   - reference: the size in bytes of the reference binary (base of PR)
-   - updated: the size in bytes of the updated binary (head of PR)
-
-  The size is reported as a comment on the PR (accessed via context).
-inputs:
-  data-directory:
-    description: >
-      Path to directory containing size data as a set of "*.json" files.
-    required: true
-runs:
-  using: composite
-  steps:
-    - name: Post a PR comment if the size has changed
-      uses: actions/github-script@v6
-      env:
-        DATA_DIRECTORY: ${{ inputs.data-directory }}
-      with:
-        script: |
-          const fs = require("fs");
-
-          const size_dir = process.env.DATA_DIRECTORY;
-
-          // Map the set of all the *.json files into an array of objects.
-          const globber = await glob.create(`${size_dir}/*.json`);
-          const files = await globber.glob();
-          const sizes = files.map(path => {
-            const contents = fs.readFileSync(path);
-            return JSON.parse(contents);
-          });
-
-          // Map each object into some text, but only if it shows any difference
-          // to report.
-          const size_reports = sizes.flatMap(size_data => {
-            const platform = size_data["platform"];
-            const reference = size_data["reference"];
-            const updated = size_data["updated"];
-
-            if (!(reference > 0)) {
-              core.setFailed(`Reference size invalid: ${reference}`);
-              return;
-            }
-
-            if (!(updated > 0)) {
-              core.setFailed(`Updated size invalid: ${updated}`);
-              return;
-            }
-
-            const formatter = Intl.NumberFormat("en", {
-              useGrouping: "always"
-            });
-
-            const updated_str = formatter.format(updated);
-            const reference_str = formatter.format(reference);
-
-            const diff = updated - reference;
-            const diff_pct = (updated / reference) - 1;
-
-            const diff_str = Intl.NumberFormat("en", {
-              useGrouping: "always",
-              sign: "exceptZero"
-            }).format(diff);
-
-            const diff_pct_str = Intl.NumberFormat("en", {
-              style: "percent",
-              useGrouping: "always",
-              sign: "exceptZero",
-              maximumFractionDigits: 2
-            }).format(diff_pct);
-
-            if (diff !== 0) {
-              // The body is created here and wrapped so "weirdly" to avoid whitespace at the start of the lines,
-              // which is interpreted as a code block by Markdown.
-              const report = `On platform \`${platform}\`:
-
-          - Original binary size: **${reference_str} B**
-          - Updated binary size: **${updated_str} B**
-          - Difference: **${diff_str} B** (${diff_pct_str})
-
-          `;
-
-              return [report];
-            } else {
-              return [];
-            }
-          });
-
-          // If there are any size changes to report, format a comment and post
-          // it.
-          if (size_reports.length > 0) {
-            const comment_sizes = size_reports.join("");
-            const body = `Code size changes for a hello-world Rust program linked with libstd with backtrace:
-
-          ${comment_sizes}`;
-
-            github.rest.issues.createComment({
-              issue_number: context.issue.number,
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              body
-            });
-          }
diff --git a/.github/workflows/check-binary-size.yml b/.github/workflows/check-binary-size.yml
deleted file mode 100644
index 5e8ba72f..00000000
--- a/.github/workflows/check-binary-size.yml
+++ /dev/null
@@ -1,159 +0,0 @@
-# This workflow checks if a PR commit has changed the size of a hello world Rust program.
-# It downloads Rustc and compiles two versions of a stage0 compiler - one using the base commit
-# of the PR, and one using the latest commit in the PR.
-# If the size of the hello world program has changed, it posts a comment to the PR.
-name: Check binary size
-
-on:
-  pull_request_target:
-    # HACK(jubilee): something broke the distributed LLVM libso and I don't know what.
-    branches: []
-#      - master
-
-# Both the "measure" and "report" jobs need to know this.
-env:
-  SIZE_DATA_DIR: sizes
-  RUST_BACKTRACE: 1
-
-# Responsibility is divided between two jobs "measure" and "report", so that the
-# job that builds (and potentnially runs) untrusted code does not have PR write
-# permission, and vice-versa.
-jobs:
-  measure:
-    name: Check binary size
-    strategy:
-      matrix:
-        # FIXME(jubilee): the immutable upload needs us to disambiguate things
-        # platform: [ubuntu-latest, windows-latest]
-        platform: [ubuntu-latest]
-    runs-on: ${{ matrix.platform }}
-    permissions:
-      contents: read
-    env:
-      # This cannot be used as a context variable in the 'uses' key later. If it
-      # changes, update those steps too.
-      BACKTRACE_DIR: backtrace
-      RUSTC_DIR: rustc
-      TEST_MAIN_RS: foo.rs
-      BASE_COMMIT: ${{ github.event.pull_request.base.sha }}
-      HEAD_COMMIT: ${{ github.event.pull_request.head.sha }}
-      SIZE_DATA_FILE: size-${{ strategy.job-index }}.json
-    steps:
-      - name: Print info
-        shell: bash
-        run: |
-          echo "Current SHA: $HEAD_COMMIT"
-          echo "Base SHA: $BASE_COMMIT"
-      # Note: the backtrace source that's cloned here is NOT the version to be
-      # patched in to std. It's cloned here to access the Github action for
-      # building and measuring the test binary.
-      - name: Clone backtrace to access Github action
-        uses: actions/checkout@v4
-        with:
-          path: ${{ env.BACKTRACE_DIR }}
-      - name: Clone Rustc
-        uses: actions/checkout@v4
-        with:
-          repository: rust-lang/rust
-          path: ${{ env.RUSTC_DIR }}
-          # Arbitrary version from 2024-04-28
-          ref: cc74ed08d53fbb440b4ab70035a92d89d418d23c
-      - name: Set up std repository and backtrace submodule for size test
-        shell: bash
-        working-directory: ${{ env.RUSTC_DIR }}
-        env:
-          PR_SOURCE_REPO: ${{ github.event.pull_request.head.repo.full_name }}
-        run: |
-          set -x
-          # Bootstrap config
-          cat <<EOF > bootstrap.toml
-          change-id = 9999999
-          [llvm]
-          download-ci-llvm = "if-unchanged"
-          [rust]
-          incremental = false
-          EOF
-
-          # Test program source
-          cat <<EOF > $TEST_MAIN_RS
-          fn main() {
-            panic!();
-          }
-          EOF
-
-          git submodule update --init library/backtrace
-
-          cd library/backtrace
-          git remote add head-pr "https://github.com/$PR_SOURCE_REPO"
-          git fetch --all
-      - name: Build binary with base version of backtrace
-        uses: ./backtrace/.github/actions/build-with-patched-std
-        with:
-          backtrace-commit: ${{ env.BASE_COMMIT }}
-          main-rs: ${{ env.TEST_MAIN_RS }}
-          rustc-dir: ${{ env.RUSTC_DIR }}
-        id: size-reference
-      - name: Build binary with PR version of backtrace
-        uses: ./backtrace/.github/actions/build-with-patched-std
-        with:
-          backtrace-commit: ${{ env.HEAD_COMMIT }}
-          main-rs: ${{ env.TEST_MAIN_RS }}
-          rustc-dir: ${{ env.RUSTC_DIR }}
-        id: size-updated
-      # There is no built-in way to "collect" all the outputs of a set of jobs
-      # run with a matrix strategy. Subsequent jobs that have a "needs"
-      # dependency on this one will be run once, when the last matrix job is
-      # run. Appending data to a single file within a matrix is subject to race
-      # conditions. So we write the size data to files with distinct names
-      # generated from the job index.
-      - name: Write sizes to file
-        uses: actions/github-script@v6
-        env:
-          SIZE_REFERENCE: ${{ steps.size-reference.outputs.test-binary-size }}
-          SIZE_UPDATED: ${{ steps.size-updated.outputs.test-binary-size }}
-          PLATFORM: ${{ matrix.platform }}
-        with:
-          script: |
-            const fs = require("fs");
-            const path = require("path");
-
-            fs.mkdirSync(process.env.SIZE_DATA_DIR, {recursive: true});
-
-            const output_data = JSON.stringify({
-              platform: process.env.PLATFORM,
-              reference: process.env.SIZE_REFERENCE,
-              updated: process.env.SIZE_UPDATED,
-            });
-
-            // The "wx" flag makes this fail if the file exists, which we want,
-            // because there should be no collisions.
-            fs.writeFileSync(
-              path.join(process.env.SIZE_DATA_DIR, process.env.SIZE_DATA_FILE),
-              output_data,
-              { flag: "wx" },
-            );
-      - name: Upload size data
-        uses: actions/upload-artifact@v4
-        with:
-          name: size-files
-          path: ${{ env.SIZE_DATA_DIR }}/${{ env.SIZE_DATA_FILE }}
-          retention-days: 1
-          if-no-files-found: error
-  report:
-    name: Report binary size changes
-    runs-on: ubuntu-latest
-    needs: measure
-    permissions:
-      pull-requests: write
-    steps:
-      # Clone backtrace to access Github composite actions to report size.
-      - uses: actions/checkout@v4
-      - name: Download size data
-        uses: actions/download-artifact@v4
-        with:
-          name: size-files
-          path: ${{ env.SIZE_DATA_DIR }}
-      - name: Analyze and report size changes
-        uses: ./.github/actions/report-code-size-changes
-        with:
-          data-directory: ${{ env.SIZE_DATA_DIR }}