diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 2184ddd49537b57..91b929732f2808f 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -202,13 +202,13 @@ jobs:
       matrix:
         include:
         - config: generic-cxx03
-          os: macos-latest
+          os: macos-15
         - config: generic-cxx23
-          os: macos-latest
+          os: macos-15
         - config: generic-modules
-          os: macos-latest
+          os: macos-15
         - config: apple-configuration
-          os: macos-latest
+          os: macos-15
         - config: apple-system
           os: macos-13
         - config: apple-system-hardened
diff --git a/libcxx/test/std/experimental/simd/simd.class/simd_unary.pass.cpp b/libcxx/test/std/experimental/simd/simd.class/simd_unary.pass.cpp
index 8cc9924a3cdae14..17ecfd3b50d255a 100644
--- a/libcxx/test/std/experimental/simd/simd.class/simd_unary.pass.cpp
+++ b/libcxx/test/std/experimental/simd/simd.class/simd_unary.pass.cpp
@@ -12,9 +12,8 @@
 //   Pass-by-value arguments with alignment greater than register width are not supported.
 // XFAIL: target=powerpc{{.*}}-ibm-{{.*}} && (clang-17 || clang-18)
 
-// FIXME: The following issue occurs on macOS 13.7 with Apple clang 15.0.0:
-//   clang: error: unable to execute command: Illegal instruction: 4
-// XFAIL: target=x86_64-apple-macosx13.7
+// This test crashes AppleClang 15 but not later versions.
+// UNSUPPORTED: apple-clang-15
 
 // FIXME: The following issue occurs on Windows to Armv7 Ubuntu Linux:
 //   Assertion failed: N->getValueType(0) == MVT::v1i1 && "Expected v1i1 type"