diff --git a/compiler-rt/test/sanitizer_common/TestCases/Linux/pthread_getaffinity_np.cpp b/compiler-rt/test/sanitizer_common/TestCases/Linux/pthread_getaffinity_np.cpp
--- a/compiler-rt/test/sanitizer_common/TestCases/Linux/pthread_getaffinity_np.cpp
+++ b/compiler-rt/test/sanitizer_common/TestCases/Linux/pthread_getaffinity_np.cpp
@@ -4,6 +4,7 @@
 // (Note: libresolv is integrated with libc, but apparently only
 // sched_getaffinity).
 // UNSUPPORTED: android
+// UNSUPPORTED: mismatched-core-count
 
 #include <assert.h>
 #include <pthread.h>
diff --git a/compiler-rt/test/sanitizer_common/lit.common.cfg.py b/compiler-rt/test/sanitizer_common/lit.common.cfg.py
--- a/compiler-rt/test/sanitizer_common/lit.common.cfg.py
+++ b/compiler-rt/test/sanitizer_common/lit.common.cfg.py
@@ -34,6 +34,11 @@
 if config.arm_thumb:
   config.available_features.add('thumb')
 
+# Using cgroups on Linux the number of available cores can be different from the
+# number of online cores.
+if os.cpu_count() != len(os.sched_getaffinity(0)):
+  config.available_features.add('mismatched-core-count')
+
 if config.host_os == 'Darwin':
   # On Darwin, we default to `abort_on_error=1`, which would make tests run
   # much slower. Let's override this and run lit tests with 'abort_on_error=0'.