Index: llvm/trunk/cmake/config-ix.cmake
===================================================================
--- llvm/trunk/cmake/config-ix.cmake
+++ llvm/trunk/cmake/config-ix.cmake
@@ -252,12 +252,15 @@
 # This check requires _GNU_SOURCE
 check_symbol_exists(sched_getaffinity sched.h HAVE_SCHED_GETAFFINITY)
 check_symbol_exists(CPU_COUNT sched.h HAVE_CPU_COUNT)
-if(HAVE_LIBPTHREAD)
-  check_library_exists(pthread pthread_getname_np "" HAVE_PTHREAD_GETNAME_NP)
-  check_library_exists(pthread pthread_setname_np "" HAVE_PTHREAD_SETNAME_NP)
-elseif(PTHREAD_IN_LIBC)
-  check_library_exists(c pthread_getname_np "" HAVE_PTHREAD_GETNAME_NP)
-  check_library_exists(c pthread_setname_np "" HAVE_PTHREAD_SETNAME_NP)
+if (NOT PURE_WINDOWS)
+  if (LLVM_PTHREAD_LIB)
+    list(APPEND CMAKE_REQUIRED_LIBRARIES ${LLVM_PTHREAD_LIB})
+  endif()
+  check_symbol_exists(pthread_getname_np pthread.h HAVE_PTHREAD_GETNAME_NP)
+  check_symbol_exists(pthread_setname_np pthread.h HAVE_PTHREAD_SETNAME_NP)
+  if (LLVM_PTHREAD_LIB)
+    list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES ${LLVM_PTHREAD_LIB})
+  endif()
 endif()
 
 # available programs checks
Index: llvm/trunk/lib/Support/Unix/Threading.inc
===================================================================
--- llvm/trunk/lib/Support/Unix/Threading.inc
+++ llvm/trunk/lib/Support/Unix/Threading.inc
@@ -204,7 +204,6 @@
 
   Name.append(buf, buf + strlen(buf));
 #elif defined(__linux__)
-#if (defined(__GLIBC__) && defined(_GNU_SOURCE)) || defined(__ANDROID__)
 #if HAVE_PTHREAD_GETNAME_NP
   constexpr uint32_t len = get_max_thread_name_length_impl();
   char Buffer[len] = {'\0'};  // FIXME: working around MSan false positive.
@@ -212,5 +211,4 @@
     Name.append(Buffer, Buffer + strlen(Buffer));
 #endif
 #endif
-#endif
 }