Index: lib/sanitizer_common/CMakeLists.txt
===================================================================
--- lib/sanitizer_common/CMakeLists.txt
+++ lib/sanitizer_common/CMakeLists.txt
@@ -11,6 +11,7 @@
   sanitizer_libc.cc
   sanitizer_libignore.cc
   sanitizer_linux.cc
+  sanitizer_linux_s390.cc
   sanitizer_mac.cc
   sanitizer_persistent_allocator.cc
   sanitizer_platform_limits_linux.cc
Index: lib/sanitizer_common/sanitizer_linux.cc
===================================================================
--- lib/sanitizer_common/sanitizer_linux.cc
+++ lib/sanitizer_common/sanitizer_linux.cc
@@ -111,34 +111,10 @@
 #endif
 
 // --------------- sanitizer_libc.h
+#ifndef __s390__
 uptr internal_mmap(void *addr, uptr length, int prot, int flags, int fd,
                    OFF_T offset) {
-#ifdef __s390__
-  struct s390_mmap_params {
-    unsigned long addr;
-    unsigned long length;
-    unsigned long prot;
-    unsigned long flags;
-    unsigned long fd;
-    unsigned long offset;
-  } params = {
-    (unsigned long)addr,
-    (unsigned long)length,
-    (unsigned long)prot,
-    (unsigned long)flags,
-    (unsigned long)fd,
-# ifdef __s390x__
-    (unsigned long)offset,
-# else
-    (unsigned long)(offset / 4096),
-# endif
-  };
-# ifdef __s390x__
-  return internal_syscall(SYSCALL(mmap), &params);
-# else
-  return internal_syscall(SYSCALL(mmap2), &params);
-# endif
-#elif SANITIZER_FREEBSD || SANITIZER_LINUX_USES_64BIT_SYSCALLS
+#if SANITIZER_FREEBSD || SANITIZER_LINUX_USES_64BIT_SYSCALLS
   return internal_syscall(SYSCALL(mmap), (uptr)addr, length, prot, flags, fd,
                           offset);
 #else
@@ -148,6 +124,7 @@
                           offset / 4096);
 #endif
 }
+#endif
 
 uptr internal_munmap(void *addr, uptr length) {
   return internal_syscall(SYSCALL(munmap), (uptr)addr, length);
Index: lib/sanitizer_common/sanitizer_linux_s390.cc
===================================================================
--- /dev/null
+++ lib/sanitizer_common/sanitizer_linux_s390.cc
@@ -0,0 +1,57 @@
+//===-- sanitizer_linux_s390.cc -------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries and implements s390-linux-specific functions from
+// sanitizer_libc.h.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+
+#if SANITIZER_LINUX && defined(__s390__)
+
+#include "sanitizer_linux.h"
+
+#include <sys/syscall.h>
+#include <unistd.h>
+
+namespace __sanitizer {
+
+// --------------- sanitizer_libc.h
+uptr internal_mmap(void *addr, uptr length, int prot, int flags, int fd,
+                   OFF_T offset) {
+  struct s390_mmap_params {
+    unsigned long addr;
+    unsigned long length;
+    unsigned long prot;
+    unsigned long flags;
+    unsigned long fd;
+    unsigned long offset;
+  } params = {
+    (unsigned long)addr,
+    (unsigned long)length,
+    (unsigned long)prot,
+    (unsigned long)flags,
+    (unsigned long)fd,
+# ifdef __s390x__
+    (unsigned long)offset,
+# else
+    (unsigned long)(offset / 4096),
+# endif
+  };
+# ifdef __s390x__
+  return syscall(__NR_mmap, &params);
+# else
+  return syscall(__NR_mmap2, &params);
+# endif
+}
+
+} // namespace __sanitizer
+
+#endif // SANITIZER_LINUX && defined(__s390__)