diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp
index d890a3a317737c..c7f5557cb6c4e6 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_posix.cpp
@@ -340,6 +340,9 @@ bool ShouldMockFailureToOpen(const char *path) {
 }
 
 #if SANITIZER_LINUX && !SANITIZER_ANDROID && !SANITIZER_GO
+# ifndef O_CLOEXEC
+#  define O_CLOEXEC 0
+# endif
 int GetNamedMappingFd(const char *name, uptr size, int *flags) {
   if (!common_flags()->decorate_proc_maps || !name)
     return -1;
diff --git a/compiler-rt/lib/xray/xray_x86_64.cpp b/compiler-rt/lib/xray/xray_x86_64.cpp
index e63ee1b3bd02eb..209aa7a106bbcc 100644
--- a/compiler-rt/lib/xray/xray_x86_64.cpp
+++ b/compiler-rt/lib/xray/xray_x86_64.cpp
@@ -49,6 +49,9 @@ retryingReadSome(int Fd, char *Begin, char *End) XRAY_NEVER_INSTRUMENT {
   return std::make_pair(TotalBytesRead, true);
 }
 
+#ifndef O_CLOEXEC
+# define O_CLOEXEC 0
+#endif
 static bool readValueFromFile(const char *Filename,
                               long long *Value) XRAY_NEVER_INSTRUMENT {
   int Fd = open(Filename, O_RDONLY | O_CLOEXEC);