diff --git a/cpython-unix/build-cpython.sh b/cpython-unix/build-cpython.sh
index 9c65394e..33391336 100755
--- a/cpython-unix/build-cpython.sh
+++ b/cpython-unix/build-cpython.sh
@@ -260,7 +260,11 @@ if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_12}" ]; then
     patch -p1 -i ${ROOT}/patch-configure-bolt-icf-safe.patch
 
     # Tweak --skip-funcs to work with our toolchain.
-    patch -p1 -i ${ROOT}/patch-configure-bolt-skip-funcs.patch
+    if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_15}" ]; then
+        patch -p1 -i ${ROOT}/patch-configure-bolt-skip-funcs-3.15.patch
+    else
+        patch -p1 -i ${ROOT}/patch-configure-bolt-skip-funcs.patch
+    fi
 fi
 
 # The optimization make targets are both phony and non-phony. This leads
diff --git a/cpython-unix/extension-modules.yml b/cpython-unix/extension-modules.yml
index c9e5df9c..1fb0860d 100644
--- a/cpython-unix/extension-modules.yml
+++ b/cpython-unix/extension-modules.yml
@@ -362,6 +362,11 @@ _lzma:
   links:
     - lzma
 
+_math_integer:
+  minimum-python-version: "3.15"
+  sources:
+   - mathintegermodule.c
+
 _md5:
   sources:
     - md5module.c
diff --git a/cpython-unix/patch-configure-bolt-skip-funcs-3.15.patch b/cpython-unix/patch-configure-bolt-skip-funcs-3.15.patch
new file mode 100644
index 00000000..df3d5a2b
--- /dev/null
+++ b/cpython-unix/patch-configure-bolt-skip-funcs-3.15.patch
@@ -0,0 +1,18 @@
+diff --git a/configure.ac b/configure.ac
+index a059a07bec2..92a7ff8d54c 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -2167,11 +2167,8 @@ then
+     [m4_normalize("
+       [-update-debug-sections]
+ 
+-      dnl At least LLVM 19.x doesn't support computed gotos in PIC compiled code.
+-      dnl Exclude functions containing computed gotos.
+-      dnl TODO this may be fixed in LLVM 20.x via https://github.com/llvm/llvm-project/pull/120267.
+-      dnl GCC's LTO creates .lto_priv.0 clones of these functions.
+-      [-skip-funcs=_PyEval_EvalFrameDefault,sre_ucs1_match/1,sre_ucs2_match/1,sre_ucs4_match/1,sre_ucs1_match.lto_priv.0/1,sre_ucs2_match.lto_priv.0/1,sre_ucs4_match.lto_priv.0/1]
++      dnl LLVM on at least 20.1.0 crashes on this symbol. Work around.
++      [-skip-funcs=RC4_options/1]
+     ")]
+   )
+ fi
diff --git a/cpython-unix/patch-jit-llvm-version-3.15.patch b/cpython-unix/patch-jit-llvm-version-3.15.patch
index 35aae48e..5a039ffb 100644
--- a/cpython-unix/patch-jit-llvm-version-3.15.patch
+++ b/cpython-unix/patch-jit-llvm-version-3.15.patch
@@ -5,8 +5,8 @@ diff --git a/Tools/jit/_llvm.py b/Tools/jit/_llvm.py
  import _targets
 
 
--_LLVM_VERSION = "19"
+-_LLVM_VERSION = "21"
 +_LLVM_VERSION = "21"
- _EXTERNALS_LLVM_TAG = "llvm-19.1.7.0"
+ _EXTERNALS_LLVM_TAG = "llvm-21.1.4.0"
 
 
diff --git a/pythonbuild/downloads.py b/pythonbuild/downloads.py
index 4981e139..75686a9f 100644
--- a/pythonbuild/downloads.py
+++ b/pythonbuild/downloads.py
@@ -93,10 +93,10 @@
         "python_tag": "cp314",
     },
     "cpython-3.15": {
-        "url": "https://www.python.org/ftp/python/3.15.0/Python-3.15.0a1.tar.xz",
-        "size": 23646768,
-        "sha256": "3194939d488eeaeefdcf990d35542d9ad1ce788789c4e2305a2060eb7058e5a4",
-        "version": "3.15.0a1",
+        "url": "https://www.python.org/ftp/python/3.15.0/Python-3.15.0a2.tar.xz",
+        "size": 23728836,
+        "sha256": "d8a0a2f4a7f3d7090cf195e81814efe95f70554955557f40e149d8694a662751",
+        "version": "3.15.0a2",
         "licenses": ["Python-2.0", "CNRI-Python"],
         "license_file": "LICENSE.cpython.txt",
         "python_tag": "cp315",
diff --git a/src/validation.rs b/src/validation.rs
index 9b4756fe..ef64d29d 100644
--- a/src/validation.rs
+++ b/src/validation.rs
@@ -731,12 +731,8 @@ const GLOBAL_EXTENSIONS: &[&str] = &[
 // _xxinterpchannels added in 3.12.
 // audioop removed in 3.13.
 
-const GLOBAL_EXTENSIONS_PYTHON_3_10: &[&str] = &[
-    "audioop",
-    "_sha256",
-    "_sha512",
-    "_xxsubinterpreters",
-];
+const GLOBAL_EXTENSIONS_PYTHON_3_10: &[&str] =
+    &["audioop", "_sha256", "_sha512", "_xxsubinterpreters"];
 
 const GLOBAL_EXTENSIONS_PYTHON_3_11: &[&str] = &[
     "audioop",
@@ -782,6 +778,22 @@ const GLOBAL_EXTENSIONS_PYTHON_3_14: &[&str] = &[
     "_zstd",
 ];
 
+const GLOBAL_EXTENSIONS_PYTHON_3_15: &[&str] = &[
+    "_interpchannels",
+    "_interpqueues",
+    "_interpreters",
+    "_math_integer",
+    "_remote_debugging",
+    "_sha2",
+    "_suggestions",
+    "_sysconfig",
+    "_tokenize",
+    "_typing",
+    "_hmac",
+    "_types",
+    "_zstd",
+];
+
 const GLOBAL_EXTENSIONS_MACOS: &[&str] = &["_scproxy"];
 
 const GLOBAL_EXTENSIONS_POSIX: &[&str] = &[
@@ -1586,9 +1598,12 @@ fn validate_extension_modules(
         "3.13" => {
             wanted.extend(GLOBAL_EXTENSIONS_PYTHON_3_13);
         }
-        "3.14" | "3.15" => {
+        "3.14" => {
             wanted.extend(GLOBAL_EXTENSIONS_PYTHON_3_14);
         }
+        "3.15" => {
+            wanted.extend(GLOBAL_EXTENSIONS_PYTHON_3_15);
+        }
         _ => {
             panic!("unhandled Python version: {python_major_minor}");
         }