diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2f6b2bb..190de55 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -28,11 +28,23 @@ jobs:
   test:
     name: Test builds
     needs: pre-commit
-    runs-on: macOS-latest
+    runs-on: ${{ matrix.runs-on }}
     strategy:
       fail-fast: false
       matrix:
-        python-version: [ "3.9", "3.10", "3.11", "3.12", "3.13-dev" ]
+        python-version: [ "3.9", "3.10", "3.11", "3.12", "3.13" ]
+        runs-on: [ "macos-latest", "macos-12" ]
+
+        exclude:
+          # Don't need to run x86 tests on every Python version
+          - python-version: "3.9"
+            runs-on: "macos-12"
+          - python-version: "3.10"
+            runs-on: "macos-12"
+          - python-version: "3.11"
+            runs-on: "macos-12"
+          - python-version: "3.13"
+            runs-on: "macos-12"
 
     steps:
     - name: Checkout
@@ -43,30 +55,60 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5.2.0
       with:
-        python-version: ${{ matrix.python-version }}
+        # -dev suffix is a no-op for published releases
+        python-version: ${{ matrix.python-version }}-dev
 
     # Initial call to the setup script sets up the environment
     - name: Set up Forge
       run: |
-        source ./setup-iOS.sh $(cut -d- -f1 <<< ${{ matrix.python-version }})
+        source ./setup-iOS.sh ${{ matrix.python-version }}
+
+    # Build packages that are pre-build dependencies
+    # Calling setup script activates existing environment
+    - name: Build bzip2
+      run: |
+        source ./setup-iOS.sh ${{ matrix.python-version }}
+        forge iOS bzip2 -vv
+
+    - name: Build ninja
+      run: |
+        source ./setup-iOS.sh ${{ matrix.python-version }}
+        forge iOS ninja -vv
 
-    # Build an example of a native package
+    # Build examples of native packages
     # Calling setup script activates existing environment
     - name: Build libjpeg
       run: |
-        source ./setup-iOS.sh $(cut -d- -f1 <<< ${{ matrix.python-version }})
-        forge iOS libjpeg
+        source ./setup-iOS.sh ${{ matrix.python-version }}
+        forge iOS libjpeg -vv
+
+    - name: Build freetype
+      run: |
+        source ./setup-iOS.sh ${{ matrix.python-version }}
+        forge iOS freetype -vv
 
     # Build an example of a simple Python package
     # Calling setup script activates existing environment
     - name: Build lru-dict
       run: |
-        source ./setup-iOS.sh $(cut -d- -f1 <<< ${{ matrix.python-version }})
-        forge iOS lru-dict
+        source ./setup-iOS.sh ${{ matrix.python-version }}
+        forge iOS lru-dict -vv
+
+    # Build a package with dependencies on other packages
+    - name: Build pillow
+      run: |
+        source ./setup-iOS.sh ${{ matrix.python-version }}
+        forge iOS pillow -vv
+
+    # Build a package with a complex build system
+    - name: Build numpy
+      run: |
+        source ./setup-iOS.sh ${{ matrix.python-version }}
+        forge iOS numpy -vv
 
     # Build an example of a simple Python package using C++
     # Calling setup script activates existing environment
     - name: Build brotli
       run: |
-        source ./setup-iOS.sh $(cut -d- -f1 <<< ${{ matrix.python-version }})
-        forge iOS brotli
+        source ./setup-iOS.sh ${{ matrix.python-version }}
+        forge iOS brotli -vv
diff --git a/recipes/numpy/patches/mobile-1.26.0.patch b/recipes/numpy/patches/mobile-1.26.0.patch
index 2d23546..edf05ca 100644
--- a/recipes/numpy/patches/mobile-1.26.0.patch
+++ b/recipes/numpy/patches/mobile-1.26.0.patch
@@ -149,13 +149,13 @@ diff -ru numpy-1.26.0-orig/vendored-meson/meson-python/mesonpy/__init__.py numpy
                      self._meson_cross_file.write_text(cross_file_data)
                      self._meson_args['setup'].extend(('--cross-file', os.fspath(self._meson_cross_file)))
 +        elif sysconfig_platform.startswith("ios-"):
-+            arch = sysconfig_platform.split("-")[-1]
++            arch = sysconfig_platform.split("-")[-2]
 +            family = "aarch64" if arch == "arm64" else arch
 +            cross_file_data = textwrap.dedent(
 +                f"""
 +                [binaries]
 +                c = [{sysconfig.get_config_var("CC")!r}]
-+                cpp = [{sysconfig.get_config_var("CC")!r}]
++                cpp = [{sysconfig.get_config_var("CXX")!r}]
 +
 +                [host_machine]
 +                system = 'ios'
diff --git a/recipes/pillow/meta.yaml b/recipes/pillow/meta.yaml
index 101d00a..5f72955 100644
--- a/recipes/pillow/meta.yaml
+++ b/recipes/pillow/meta.yaml
@@ -15,6 +15,8 @@ build:
     # libfreetype references both libz and libbz2
     # but doesn't link them into the static library
     - LDFLAGS=-lz -lbz2
+  config:
+    - debug=true
 
 requirements:
   host:
diff --git a/recipes/pillow/patches/setup-9.4.0.patch b/recipes/pillow/patches/setup-9.4.0.patch
index 006dc9c..7bf32a4 100644
--- a/recipes/pillow/patches/setup-9.4.0.patch
+++ b/recipes/pillow/patches/setup-9.4.0.patch
@@ -1,10 +1,11 @@
 Common subdirectories: Pillow-9.4.0-orig/Tests and Pillow-9.4.0/Tests
+Common subdirectories: Pillow-9.4.0-orig/__pycache__ and Pillow-9.4.0/__pycache__
 Common subdirectories: Pillow-9.4.0-orig/depends and Pillow-9.4.0/depends
 Common subdirectories: Pillow-9.4.0-orig/docs and Pillow-9.4.0/docs
 diff -u Pillow-9.4.0-orig/setup.py Pillow-9.4.0/setup.py
---- Pillow-9.4.0-orig/setup.py	2023-01-02 08:17:32
-+++ Pillow-9.4.0/setup.py	2023-09-21 10:16:17
-@@ -408,10 +408,19 @@
+--- Pillow-9.4.0-orig/setup.py	2023-01-01 16:17:32
++++ Pillow-9.4.0/setup.py	2024-09-25 11:17:51
+@@ -408,10 +408,22 @@
                  self.extensions.remove(extension)
                  break
 
@@ -19,14 +20,17 @@ diff -u Pillow-9.4.0-orig/setup.py Pillow-9.4.0/setup.py
 +                ("watchos", False): ["--sdk", "watchos"],
 +                ("watchos", True): ["--sdk", "watchsimulator"],
 +                ("darwin", False): [],
-+            }[sys.platform, getattr(sys.implementation, "_multiarch", "").endswith("simulator")]
++            }[
++                sys.platform,
++                getattr(sys.implementation, "_multiarch", "").endswith("simulator"),
++            ]
              sdk_path = (
 -                subprocess.check_output(["xcrun", "--show-sdk-path"])
 +                subprocess.check_output(["xcrun", "--show-sdk-path"] + sdk)
                  .strip()
                  .decode("latin1")
              )
-@@ -556,10 +564,15 @@
+@@ -556,10 +568,15 @@
                  _add_directory(library_dirs, "/usr/X11/lib")
                  _add_directory(include_dirs, "/usr/X11/include")
 
@@ -43,3 +47,16 @@ diff -u Pillow-9.4.0-orig/setup.py Pillow-9.4.0/setup.py
          elif (
              sys.platform.startswith("linux")
              or sys.platform.startswith("gnu")
+@@ -593,7 +610,9 @@
+         # FIXME: check /opt/stuff directories here?
+
+         # standard locations
+-        if not self.disable_platform_guessing:
++        if not (
++            self.disable_platform_guessing or sys.platform in {"ios", "tvos", "watchos"}
++        ):
+             _add_directory(library_dirs, "/usr/local/lib")
+             _add_directory(include_dirs, "/usr/local/include")
+
+Common subdirectories: Pillow-9.4.0-orig/src and Pillow-9.4.0/src
+Common subdirectories: Pillow-9.4.0-orig/winbuild and Pillow-9.4.0/winbuild
diff --git a/recipes/pillow/patches/setup.patch b/recipes/pillow/patches/setup.patch
index 892122b..d678cae 100644
--- a/recipes/pillow/patches/setup.patch
+++ b/recipes/pillow/patches/setup.patch
@@ -1,6 +1,10 @@
-diff -ur pillow-10.4.0-orig/setup.py pillow-10.4.0/setup.py
---- pillow-10.4.0-orig/setup.py	2024-07-01 14:02:01
-+++ pillow-10.4.0/setup.py	2024-09-05 14:20:16
+Common subdirectories: pillow-10.4.0-orig/Tests and pillow-10.4.0/Tests
+Common subdirectories: pillow-10.4.0-orig/_custom_build and pillow-10.4.0/_custom_build
+Common subdirectories: pillow-10.4.0-orig/depends and pillow-10.4.0/depends
+Common subdirectories: pillow-10.4.0-orig/docs and pillow-10.4.0/docs
+diff -u pillow-10.4.0-orig/setup.py pillow-10.4.0/setup.py
+--- pillow-10.4.0-orig/setup.py	2024-06-30 23:02:01
++++ pillow-10.4.0/setup.py	2024-09-25 11:15:21
 @@ -422,10 +422,22 @@
                  self.extensions.remove(extension)
                  break
@@ -46,3 +50,17 @@ diff -ur pillow-10.4.0-orig/setup.py pillow-10.4.0/setup.py
          elif (
              sys.platform.startswith("linux")
              or sys.platform.startswith("gnu")
+@@ -618,7 +635,10 @@
+         # FIXME: check /opt/stuff directories here?
+
+         # standard locations
+-        if not self.disable_platform_guessing:
++        # The standard locations aren't standard on iOS et al.
++        if not (
++            self.disable_platform_guessing or sys.platform in {"ios", "tvos", "watchos"}
++        ):
+             _add_directory(library_dirs, "/usr/local/lib")
+             _add_directory(include_dirs, "/usr/local/include")
+
+Common subdirectories: pillow-10.4.0-orig/src and pillow-10.4.0/src
+Common subdirectories: pillow-10.4.0-orig/winbuild and pillow-10.4.0/winbuild
diff --git a/src/forge/build.py b/src/forge/build.py
index 06c3462..0e29dea 100644
--- a/src/forge/build.py
+++ b/src/forge/build.py
@@ -217,6 +217,7 @@ def compile_env(self, **kwargs) -> dict[str:str]:
         ar = sysconfig_data["AR"]
 
         cc = sysconfig_data["CC"]
+        cxx = sysconfig_data["CXX"]
 
         cflags = self.cross_venv.sysconfig_data["CFLAGS"]
 
@@ -258,7 +259,9 @@ def compile_env(self, **kwargs) -> dict[str:str]:
         env = {
             "AR": ar,
             "CC": cc,
+            "CXX": cxx,
             "CFLAGS": cflags,
+            "CXXFLAGS": cflags,
             "LDFLAGS": ldflags,
             "INSTALL_ROOT": str(self.cross_venv.install_root),
         }
@@ -560,6 +563,10 @@ def _build(self):
         else:
             output_dir = str(Path.cwd() / "dist")
 
+        config_args = []
+        for config in self.package.meta["build"]["config"]:
+            config_args.extend(["-C", config])
+
         self.cross_venv.run(
             self.log_file,
             [
@@ -570,7 +577,9 @@ def _build(self):
                 "--wheel",
                 "--outdir",
                 output_dir,
-            ],
+                "-v",
+            ]
+            + config_args,
             cwd=self.build_path,
             env=self.compile_env(**script_env),
         )
diff --git a/src/forge/schema/meta-schema.yaml b/src/forge/schema/meta-schema.yaml
index 5e66b4d..b6d37c8 100644
--- a/src/forge/schema/meta-schema.yaml
+++ b/src/forge/schema/meta-schema.yaml
@@ -65,6 +65,11 @@ properties:
         default: []
         items:
           type: string
+      config:           # Config arguments to pass to python -m build in the form -C value
+        type: array
+        default: []
+        items:
+          type: string
     additionalProperties: false
 
   requirements: