diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index c107c340209..85af5ffd2a6 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -9,7 +9,7 @@ on:
   workflow_dispatch:
     inputs:
       pr:
-        description: Pull request number to build
+        description: Pull request numbers to build together, separated by spaces or commas (up to 8)
         required: true
         type: string
       linux:
@@ -77,38 +77,47 @@ jobs:
                   throw new Error('Only collaborators with write access can start or rerun builds');
                 }
               }
-              if (!/^[1-9][0-9]*$/.test(process.env.PR_NUMBER)) {
-                throw new Error('Enter a positive pull request number');
+              if (!/^[1-9][0-9]*([ ,]+[1-9][0-9]*){0,7}$/.test(process.env.PR_NUMBER.trim())) {
+                throw new Error('Enter up to 8 positive pull request numbers separated by spaces or commas');
               }
             }
-            const pull_number = manual ? Number(process.env.PR_NUMBER) : context.payload.pull_request.number;
-            if (!Number.isSafeInteger(pull_number) || pull_number < 1) {
+            const numbers = manual
+              ? [...new Set(process.env.PR_NUMBER.trim().split(/[ ,]+/).map(Number))]
+              : [context.payload.pull_request.number];
+            if (numbers.some((pull_number) => !Number.isSafeInteger(pull_number) || pull_number < 1)) {
               throw new Error('Invalid pull request number');
             }
-            let { data: pr } = await github.rest.pulls.get({ owner, repo, pull_number });
-            for (let attempt = 0; pr.mergeable === null && attempt < 10; ++attempt) {
-              await new Promise((resolve) => setTimeout(resolve, 3000));
-              ({ data: pr } = await github.rest.pulls.get({ owner, repo, pull_number }));
-            }
-            if (pr.state !== 'open' || pr.base.ref !== 'main') {
-              throw new Error('The pull request must be open and target main');
-            }
-            if (!manual && pr.head.sha !== context.payload.pull_request.head.sha) {
-              throw new Error('The pull request has newer commits; use the latest run');
-            }
-            if (pr.mergeable === false) {
-              throw new Error('The pull request does not merge cleanly into main; rebase it first');
-            }
+            const pulls = [];
+            const paths = [];
+            let truncated = false;
             let relinker = manual;
-            if (!manual) {
-              const { data: commits } = await github.rest.repos.listCommits({
-                owner, repo, sha: 'main', author: pr.user.login, per_page: 1
-              });
-              relinker = commits.length > 0;
+            for (const pull_number of numbers) {
+              let { data: pr } = await github.rest.pulls.get({ owner, repo, pull_number });
+              for (let attempt = 0; pr.mergeable === null && attempt < 10; ++attempt) {
+                await new Promise((resolve) => setTimeout(resolve, 3000));
+                ({ data: pr } = await github.rest.pulls.get({ owner, repo, pull_number }));
+              }
+              if (pr.state !== 'open' || pr.base.ref !== 'main') {
+                throw new Error(`Pull request #${pull_number} must be open and target main`);
+              }
+              if (!manual && pr.head.sha !== context.payload.pull_request.head.sha) {
+                throw new Error('The pull request has newer commits; use the latest run');
+              }
+              if (pr.mergeable === false) {
+                throw new Error(`Pull request #${pull_number} does not merge cleanly into main; rebase it first`);
+              }
+              if (!manual) {
+                const { data: commits } = await github.rest.repos.listCommits({
+                  owner, repo, sha: 'main', author: pr.user.login, per_page: 1
+                });
+                relinker = commits.length > 0;
+              }
+              const files = await github.paginate(github.rest.pulls.listFiles, { owner, repo, pull_number, per_page: 100 });
+              truncated ||= files.length >= 3000;
+              paths.push(...files.flatMap((file) => [file.filename, file.previous_filename].filter(Boolean)));
+              pulls.push({ number: pull_number, head: pr.head.sha });
             }
-            const files = await github.paginate(github.rest.pulls.listFiles, { owner, repo, pull_number, per_page: 100 });
-            const paths = files.flatMap((file) => [file.filename, file.previous_filename].filter(Boolean));
-            const touches = (...prefixes) => files.length >= 3000 ||
+            const touches = (...prefixes) => truncated ||
               paths.some((path) => prefixes.some((prefix) => prefix.endsWith('/') ? path.startsWith(prefix) : path === prefix));
             const workflow = '.github/workflows/build.yml';
             const libc = 'core/libs/prx/libc/';
@@ -121,15 +130,16 @@ jobs:
             const writeWatch = touches('core/libs/tests/write_watch/', 'core/libs/tests/WriteWatch.cpp', libc, workflow);
             const { data: main } = await github.rest.repos.getBranch({ owner, repo, branch: 'main' });
             core.setOutput('sha', main.commit.sha);
-            core.setOutput('pr', String(pull_number));
-            core.setOutput('head', pr.head.sha);
+            core.setOutput('pr', pulls.map((pull) => pull.number).join(' '));
+            core.setOutput('head', pulls.map((pull) => pull.head).join(' '));
             core.setOutput('relinker', relinker);
             core.setOutput('register-context', registerContext);
             core.setOutput('write-watch', writeWatch);
             core.setOutput('full', manual);
-            core.info(`PR #${pull_number} at ${pr.head.sha} merged into main at ${main.commit.sha}`);
+            const merged = pulls.map((pull) => `PR #${pull.number} at ${pull.head} merged into main at ${main.commit.sha}`);
+            merged.forEach((line) => core.info(line));
             await core.summary.addRaw(
-              `PR #${pull_number} at ${pr.head.sha} merged into main at ${main.commit.sha}: full builds ${manual ? 'enabled' : 'disabled'}, ` +
+              `${merged.join(', then ')}: full builds ${manual ? 'enabled' : 'disabled'}, ` +
               `relinker ${relinker ? 'enabled' : 'skipped: no relinker file changed or the author has no commit in main'}, ` +
               `register context tests ${registerContext ? 'enabled' : 'skipped'}, write watch tests ${writeWatch ? 'enabled' : 'skipped'}`
             ).write();
@@ -167,9 +177,15 @@ jobs:
           PR_NUMBER: ${{ needs.eligibility.outputs.pr }}
           PR_HEAD: ${{ needs.eligibility.outputs.head }}
         run: |
-          git fetch --no-tags --unshallow origin "refs/pull/$PR_NUMBER/head"
-          if [ "$(git rev-parse FETCH_HEAD)" != "$PR_HEAD" ]; then echo "::error::The pull request has newer commits; start a new build"; exit 1; fi
-          if ! git -c user.name=ci -c user.email=ci@localhost merge --no-ff --no-edit FETCH_HEAD; then echo "::error::The pull request does not merge cleanly into main; rebase it first"; exit 1; fi
+          read -ra numbers <<< "$PR_NUMBER"
+          read -ra heads <<< "$PR_HEAD"
+          refspecs=()
+          for number in "${numbers[@]}"; do refspecs+=("refs/pull/$number/head:refs/remotes/pull/$number"); done
+          git fetch --no-tags --unshallow origin "${refspecs[@]}"
+          for i in "${!numbers[@]}"; do
+            if [ "$(git rev-parse "refs/remotes/pull/${numbers[i]}")" != "${heads[i]}" ]; then echo "::error::Pull request #${numbers[i]} has newer commits; start a new build"; exit 1; fi
+            if ! git -c user.name=ci -c user.email=ci@localhost merge --no-ff --no-edit "refs/remotes/pull/${numbers[i]}"; then echo "::error::Pull request #${numbers[i]} does not merge cleanly into main and the pull requests before it; rebase it first"; exit 1; fi
+          done
       - if: runner.os == 'Windows'
         id: toolchain
         uses: actions/cache@v6
@@ -235,9 +251,15 @@ jobs:
           PR_NUMBER: ${{ needs.eligibility.outputs.pr }}
           PR_HEAD: ${{ needs.eligibility.outputs.head }}
         run: |
-          git fetch --no-tags --unshallow origin "refs/pull/$PR_NUMBER/head"
-          if [ "$(git rev-parse FETCH_HEAD)" != "$PR_HEAD" ]; then echo "::error::The pull request has newer commits; start a new build"; exit 1; fi
-          if ! git -c user.name=ci -c user.email=ci@localhost merge --no-ff --no-edit FETCH_HEAD; then echo "::error::The pull request does not merge cleanly into main; rebase it first"; exit 1; fi
+          read -ra numbers <<< "$PR_NUMBER"
+          read -ra heads <<< "$PR_HEAD"
+          refspecs=()
+          for number in "${numbers[@]}"; do refspecs+=("refs/pull/$number/head:refs/remotes/pull/$number"); done
+          git fetch --no-tags --unshallow origin "${refspecs[@]}"
+          for i in "${!numbers[@]}"; do
+            if [ "$(git rev-parse "refs/remotes/pull/${numbers[i]}")" != "${heads[i]}" ]; then echo "::error::Pull request #${numbers[i]} has newer commits; start a new build"; exit 1; fi
+            if ! git -c user.name=ci -c user.email=ci@localhost merge --no-ff --no-edit "refs/remotes/pull/${numbers[i]}"; then echo "::error::Pull request #${numbers[i]} does not merge cleanly into main and the pull requests before it; rebase it first"; exit 1; fi
+          done
           git submodule update --init --recursive
       - uses: hendrikmuhs/ccache-action@v1.2.24
         with:
@@ -305,9 +327,15 @@ jobs:
           PR_NUMBER: ${{ needs.eligibility.outputs.pr }}
           PR_HEAD: ${{ needs.eligibility.outputs.head }}
         run: |
-          git fetch --no-tags --unshallow origin "refs/pull/$PR_NUMBER/head"
-          if [ "$(git rev-parse FETCH_HEAD)" != "$PR_HEAD" ]; then echo "::error::The pull request has newer commits; start a new build"; exit 1; fi
-          if ! git -c user.name=ci -c user.email=ci@localhost merge --no-ff --no-edit FETCH_HEAD; then echo "::error::The pull request does not merge cleanly into main; rebase it first"; exit 1; fi
+          read -ra numbers <<< "$PR_NUMBER"
+          read -ra heads <<< "$PR_HEAD"
+          refspecs=()
+          for number in "${numbers[@]}"; do refspecs+=("refs/pull/$number/head:refs/remotes/pull/$number"); done
+          git fetch --no-tags --unshallow origin "${refspecs[@]}"
+          for i in "${!numbers[@]}"; do
+            if [ "$(git rev-parse "refs/remotes/pull/${numbers[i]}")" != "${heads[i]}" ]; then echo "::error::Pull request #${numbers[i]} has newer commits; start a new build"; exit 1; fi
+            if ! git -c user.name=ci -c user.email=ci@localhost merge --no-ff --no-edit "refs/remotes/pull/${numbers[i]}"; then echo "::error::Pull request #${numbers[i]} does not merge cleanly into main and the pull requests before it; rebase it first"; exit 1; fi
+          done
           git submodule update --init --recursive
       - id: toolchain
         uses: actions/cache@v6