diff --git a/.github/workflows/build-pyre-check.yml b/.github/workflows/build-pyre-check.yml
new file mode 100644
index 00000000000..1274577d373
--- /dev/null
+++ b/.github/workflows/build-pyre-check.yml
@@ -0,0 +1,220 @@
+# SPDX-FileCopyrightText: 2026 The RISE Project
+# SPDX-License-Identifier: MIT
+---
+# This workflow mirrors Pysa's own `pysa` workflow
+# (https://github.com/facebook/Pysa/blob/v0.10.0/.github/workflows/pysa.yml),
+# followed by the wheel packaging of
+# https://github.com/facebook/Pysa/blob/v0.10.0/scripts/pypi/build_pypi_package.py
+name: Build pyre-check wheels (riscv64)
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'Version glob to (re)build; empty builds every version of docs/packages/pyre-check.yaml not released yet'
+        required: false
+        default: ''
+  pull_request:
+    branches: [main]
+    paths:
+      - '.github/workflows/build-pyre-check.yml'
+      - 'docs/packages/pyre-check.yaml'
+  push:
+    branches: [main]
+    paths:
+      - '.github/workflows/build-pyre-check.yml'
+      - 'docs/packages/pyre-check.yaml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read  # to fetch code (actions/checkout)
+
+env:
+  # Upstream builds on ubuntu-latest with Ubuntu's own opam; riscv64/ubuntu:24.04
+  # is the same userland, and its glibc 2.39 matches the runner.
+  BUILD_IMAGE: docker.io/riscv64/ubuntu:24.04
+
+jobs:
+  setup:
+    uses: $/.github/workflows/_setup.yml
+    with:
+      package: pyre-check
+      version: ${{ inputs.version }}
+
+  build_wheel:
+    needs: [setup]
+    if: needs.setup.outputs.versions != '[]'
+    strategy:
+      fail-fast: false
+      matrix:
+        version: ${{ fromJSON(needs.setup.outputs.versions) }}
+    name: Build pyre-check ${{ matrix.version }} manylinux_riscv64
+    runs-on: ubuntu-24.04-riscv
+    # The OCaml compiler (flambda), ~100 opam packages and Pyre itself are all
+    # compiled from source on the riscv64 runner.
+    timeout-minutes: 1440
+
+    env:
+      PYRE_VERSION: ${{ matrix.version }}
+
+    steps:
+      - name: Checkout Pysa v${{ env.PYRE_VERSION }}
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          repository: facebook/Pysa
+          ref: v${{ env.PYRE_VERSION }}
+          persist-credentials: false
+
+      - name: Checkout python-wheels
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          path: python-wheels
+          persist-credentials: false
+
+      - name: Apply riscv64 patches
+        run: git apply -v python-wheels/patches/pyre-check/${{ env.PYRE_VERSION }}/*.patch
+
+      - name: Build pyre.bin and the wheel
+        shell: bash
+        run: |
+          cat > riscv64-build.sh <<'EOF'
+          set -eux
+
+          export DEBIAN_FRONTEND=noninteractive
+          apt-get update -qq
+          apt-get install -y --no-install-recommends \
+            opam \
+            build-essential bzip2 ca-certificates curl file git m4 make \
+            patch pkg-config python3 python3-venv rsync unzip xz-utils
+
+          git config --global --add safe.directory /workspace
+          export OPAMYES=1 OPAMROOTISOK=1
+
+          python3 -m venv /tmp/buildenv
+          # Ubuntu 24.04's pip 24.0 matches no manylinux_*_riscv64 tag.
+          /tmp/buildenv/bin/pip install --quiet --upgrade pip
+          export PIP_EXTRA_INDEX_URL=https://pypi.riseproject.dev/simple/ PIP_PREFER_BINARY=1
+          /tmp/buildenv/bin/pip install --quiet -r requirements.txt
+          export PATH="/tmp/buildenv/bin:${HOME}/.opam/pyre-4.14.2/bin:${PATH}"
+
+          ./scripts/setup.sh --local --release --no-tests
+
+          # The released wheels' WHEEL file names bdist_wheel 0.38.4 as generator.
+          pip install --quiet 'setuptools<70' 'wheel==0.38.4' twine
+          mkdir -p dist
+
+          # build_pypi_package.py builds the wheel under tempfile.mkdtemp() (which
+          # defaults to /tmp) and then os.replace()s it into --output-dir. /tmp is
+          # the container's own overlay/tmpfs, a different device from /workspace
+          # (bind-mounted from the runner host), so that replace() fails with
+          # "Invalid cross-device link" (os.replace/rename(2) can't cross devices).
+          # Point TMPDIR at a directory on the same bind-mounted filesystem as
+          # ../dist so the final move is same-device.
+          mkdir -p /workspace/tmp
+          export TMPDIR=/workspace/tmp
+
+          cd scripts
+          python -m pypi \
+            --typeshed-path ../stubs/typeshed/typeshed \
+            --version "${PYRE_VERSION}" \
+            --output-dir ../dist
+          cd ..
+          rm dist/*.tar.gz
+          EOF
+
+          # `opam switch create` builds the compiler; tee the whole run to an
+          # artifact since a multi-hour job's log is sometimes dropped.
+          podman run \
+            --log-driver=none \
+            --network=host \
+            -v "$(pwd)":/workspace \
+            --workdir /workspace \
+            -e PYRE_VERSION="${PYRE_VERSION}" \
+            --pull=newer \
+            "${BUILD_IMAGE}" \
+            bash riscv64-build.sh 2>&1 | tee build.log
+
+      - name: Upload build log
+        if: failure()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: pyre-check-${{ env.PYRE_VERSION }}-build-log
+          path: build.log
+
+      - name: Store wheel
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: pyre-check-${{ env.PYRE_VERSION }}-py3-manylinux_riscv64
+          path: dist/*.whl
+          if-no-files-found: error
+          retention-days: 1
+          compression-level: 0
+
+      - name: Test the wheel
+        shell: bash
+        run: |
+          cat > riscv64-test.sh <<'EOF'
+          set -eux
+
+          export DEBIAN_FRONTEND=noninteractive
+          apt-get update -qq
+          apt-get install -y --no-install-recommends ca-certificates file python3 python3-venv
+
+          file dist/*.whl
+          python3 -m venv /tmp/testenv
+          /tmp/testenv/bin/pip install --quiet --upgrade pip
+          export PIP_EXTRA_INDEX_URL=https://pypi.riseproject.dev/simple/ PIP_PREFER_BINARY=1
+          /tmp/testenv/bin/pip install --quiet dist/*.whl
+          export PATH="/tmp/testenv/bin:${PATH}"
+
+          file "$(command -v pyre.bin)"
+          pyre --version
+
+          # Upstream's own `pysa` workflow test, run against the installed wheel.
+          # v0.10.0 removed the Pyre1 backend, but the app still ships only Pyre1
+          # expectations (result.json, no result.pyrefly.json), so upstream's runner
+          # cannot pass on any arch; run its analysis and require taint issues in app.py.
+          # The pyrefly.toml scopes Pyrefly to the app instead of the whole checkout.
+          cd documentation/deliberately_vulnerable_flask_app
+          . ./setup.sh
+          touch pyrefly.toml
+          python -mPysa.client.pyre --noninteractive analyze --use-pyrefly --no-verify > result.pyrefly.actual
+          python3 - <<'PY'
+          import json
+          found = {(i["code"], i["define"]) for i in json.load(open("result.pyrefly.actual"))}
+          expected = {(i["code"], i["define"]) for i in json.load(open("result.json"))}
+          print(f"{len(found)} issues found, {len(found & expected)} of the {len(expected)} Pyre1 ones")
+          for issue in sorted(found):
+              print(*issue)
+          assert any(define.startswith("app.") for _, define in found)
+          PY
+          EOF
+
+          podman run -t \
+            --log-driver=none \
+            --network=host \
+            -v "$(pwd)":/workspace \
+            --workdir /workspace \
+            --pull=newer \
+            "${BUILD_IMAGE}" \
+            bash riscv64-test.sh
+
+  publish:
+    name: Publish pyre-check ${{ matrix.version }}
+    needs: [setup, build_wheel]
+    if: needs.setup.outputs.versions != '[]'
+    strategy:
+      fail-fast: false
+      matrix:
+        version: ${{ fromJSON(needs.setup.outputs.versions) }}
+    permissions:
+      contents: write
+      pull-requests: write
+    uses: $/.github/workflows/_publish-wheel.yml
+    secrets:
+      app-private-key: ${{ secrets.RISEPROJECT_APP_PRIVATE_KEY }}
+    with:
+      artifact-pattern: pyre-check-${{ matrix.version }}-*-manylinux_riscv64
diff --git a/docs/packages/pyre-check.yaml b/docs/packages/pyre-check.yaml
new file mode 100644
index 00000000000..c277276dc2b
--- /dev/null
+++ b/docs/packages/pyre-check.yaml
@@ -0,0 +1,5 @@
+package-name: pyre-check
+source-code: https://github.com/facebook/Pysa
+license: MIT
+versions:
+- version: 0.10.0
diff --git a/patches/pyre-check/0.10.0/0001-scripts-pypi-package-the-client-as-Pysa.patch b/patches/pyre-check/0.10.0/0001-scripts-pypi-package-the-client-as-Pysa.patch
new file mode 100644
index 00000000000..71ede208a9d
--- /dev/null
+++ b/patches/pyre-check/0.10.0/0001-scripts-pypi-package-the-client-as-Pysa.patch
@@ -0,0 +1,53 @@
+From: RISE Project <info@riseproject.dev>
+Subject: [PATCH] scripts/pypi: package the client as Pysa, as released in 0.10.0
+
+The pyre-check 0.10.0 wheels on PyPI (uploaded 2026-08-06) were cut after
+the v0.10.0 tag, from f3057a5 "Update references of facebook/pyre-check.git
+to facebook/Pysa.git" (2026-08-05), the only commit in between. It touches
+nothing but packaging: the client ships as the `Pysa` package instead of
+`pyre_check` (the `pyre` console script is `Pysa.client.pyre:main`, which is
+also what tools/pysa_integration_tests' `--run-from=python-package` runs),
+and the metadata names facebook/Pysa and pysa@meta.com.
+
+Backport its two scripts/pypi hunks so the riscv64 wheel has the same
+layout and metadata as the released ones.
+
+Upstream-Status: Backport [https://github.com/facebook/Pysa/commit/f3057a5f4f9ff354a76e72af47bb7d9d7b35673d]
+
+diff --git a/scripts/pypi/build_pypi_package.py b/scripts/pypi/build_pypi_package.py
+index 3d42918..baf7a02 100644
+--- a/scripts/pypi/build_pypi_package.py
++++ b/scripts/pypi/build_pypi_package.py
+@@ -27,7 +27,7 @@ from twine.commands.check import check as twine_check
+ 
+ from .setup import run as run_setup
+ 
+-MODULE_NAME = "pyre_check"
++MODULE_NAME = "Pysa"
+ EXPECTED_LD_PATH = "/lib64/ld-linux-x86-64.so.2"
+ 
+ LOG: logging.Logger = logging.getLogger(__name__)
+diff --git a/scripts/pypi/setup.py b/scripts/pypi/setup.py
+index 0de9b66..6bc54d6 100644
+--- a/scripts/pypi/setup.py
++++ b/scripts/pypi/setup.py
+@@ -84,15 +84,15 @@ def run(
+     setup(
+         name=package_name,
+         version=package_version,
+-        description="A performant type checker for Python",
++        description="A performant type checker and security-focused static analyzer for Python",
+         long_description=long_description,
+         long_description_content_type="text/markdown",
+         url="https://pyre-check.org/",
+-        download_url="https://github.com/facebook/pyre-check",
++        download_url="https://github.com/facebook/Pysa",
+         author="Facebook",
+-        author_email="pyre@fb.com",
++        author_email="pysa@meta.com",
+         maintainer="Facebook",
+-        maintainer_email="pyre@fb.com",
++        maintainer_email="pysa@meta.com",
+         license="MIT",
+         classifiers=[
+             "Development Status :: 5 - Production/Stable",
diff --git a/patches/pyre-check/0.10.0/0002-Build-and-package-pyre.bin-on-riscv64.patch b/patches/pyre-check/0.10.0/0002-Build-and-package-pyre.bin-on-riscv64.patch
new file mode 100644
index 00000000000..df4711cb4a6
--- /dev/null
+++ b/patches/pyre-check/0.10.0/0002-Build-and-package-pyre.bin-on-riscv64.patch
@@ -0,0 +1,80 @@
+From: RISE Project <info@riseproject.dev>
+Subject: [PATCH] Build and package pyre.bin on riscv64
+
+Three x86_64/aarch64 assumptions stop a riscv64 build or make its binary
+unusable:
+
+- hh_shared.c's spin-wait in hh_mem_inner falls through to x86's `pause`
+  for everything that is not aarch64/ppc64. On riscv64 `pause` is the
+  Zihintpause mnemonic, which the assembler rejects for the default
+  rv64gc ("instruction requires the following: 'Zihintpause'"), so the
+  build fails. Emit its encoding with `.insn` instead: it is a FENCE hint,
+  so cores without Zihintpause execute it as a no-op.
+
+- SHARED_MEM_INIT maps the shared heap with MAP_FIXED at 0x500000000000
+  (80 TiB). riscv64 hardware commonly implements only Sv39, whose user
+  address space ends at 256 GiB (0x4000000000), so that mmap fails with
+  ENOMEM and every pyre.bin command that initializes shared memory exits
+  with "Error initializing". Use 0x1000000000 (64 GiB) on riscv64: it
+  lies below the 2/3*TASK_SIZE PIE load address and far from the
+  top-down mmap area on Sv39, and is valid on Sv48/Sv57 as well. The
+  address stays fixed, as the comment requires.
+
+- scripts/pypi/build_pypi_package.py only accepts a dynamically linked
+  binary whose interpreter is x86_64's ld.so, and always names the
+  wheel manylinux1_x86_64. Accept riscv64's ld.so and tag the wheel
+  manylinux_2_39_riscv64 (glibc 2.39, Ubuntu 24.04, the build image).
+
+Upstream-Status: To upstream [facebook/Pysa only builds release binaries on x86_64 Linux and arm64 macOS]
+
+diff --git a/scripts/pypi/build_pypi_package.py b/scripts/pypi/build_pypi_package.py
+index baf7a02..b19abeb 100644
+--- a/scripts/pypi/build_pypi_package.py
++++ b/scripts/pypi/build_pypi_package.py
+@@ -28,7 +28,9 @@ from twine.commands.check import check as twine_check
+ from .setup import run as run_setup
+ 
+ MODULE_NAME = "Pysa"
+-EXPECTED_LD_PATH = "/lib64/ld-linux-x86-64.so.2"
++EXPECTED_LD_PATH = {
++    "riscv64": "/lib/ld-linux-riscv64-lp64d.so.1",
++}.get(platform.machine(), "/lib64/ld-linux-x86-64.so.2")
+ 
+ LOG: logging.Logger = logging.getLogger(__name__)
+ 
+@@ -53,6 +55,8 @@ def get_source_distribution_and_wheel(artifact_directory: Path) -> BuildArtifact
+ def _distribution_platform() -> str:
+     system = platform.system()
+     if system == "Linux":
++        if platform.machine() == "riscv64":
++            return "-manylinux_2_39_riscv64"
+         # Currently we only ever build on Intel Linux machines.
+         return "-manylinux1_x86_64"
+     elif system == "Darwin":
+diff --git a/source/hack_parallel/hack_parallel/heap/hh_shared.c b/source/hack_parallel/hack_parallel/heap/hh_shared.c
+index e386387..c0a2d4d 100644
+--- a/source/hack_parallel/hack_parallel/heap/hh_shared.c
++++ b/source/hack_parallel/hack_parallel/heap/hh_shared.c
+@@ -161,7 +161,12 @@ typedef struct {
+ 
+ /* Fix the location of our shared memory so we can save and restore the
+  * hashtable easily */
++#if defined(__riscv) && __riscv_xlen == 64
++/* Sv39 caps user space at 256 GiB, so 80 TiB is unmappable there. */
++#define SHARED_MEM_INIT ((char*)0x1000000000ll)
++#else
+ #define SHARED_MEM_INIT ((char*)0x500000000000ll)
++#endif
+ 
+ /* As a sanity check when loading from a file */
+ static const uint64_t MAGIC_CONSTANT = 0xfacefacefaceb000ull;
+@@ -1390,6 +1395,9 @@ int hh_mem_inner(value key) {
+     while (hashtbl[slot].addr == HASHTBL_WRITE_IN_PROGRESS) {
+ #if defined(__aarch64__) || defined(__powerpc64__)
+       asm volatile("yield" : : : "memory");
++#elif defined(__riscv)
++      /* Zihintpause `pause`, a plain FENCE hint where it is not implemented. */
++      asm volatile(".insn i 0x0f, 0, x0, x0, 0x010" : : : "memory");
+ #else
+       asm volatile("pause" : : : "memory");
+ #endif