diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_signal_interceptors.inc b/compiler-rt/lib/sanitizer_common/sanitizer_signal_interceptors.inc
--- a/compiler-rt/lib/sanitizer_common/sanitizer_signal_interceptors.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_signal_interceptors.inc
@@ -53,7 +53,13 @@
 
 INTERCEPTOR(int, sigaction_symname, int signum,
             const __sanitizer_sigaction *act, __sanitizer_sigaction *oldact) {
-  if (GetHandleSignalMode(signum) == kHandleSignalExclusive) return 0;
+  if (GetHandleSignalMode(signum) == kHandleSignalExclusive) {
+    if (oldact) {
+      act = nullptr;
+    } else {
+      return 0;
+    }
+  }
   SIGNAL_INTERCEPTOR_SIGACTION_IMPL(signum, act, oldact);
 }
 #define INIT_SIGACTION COMMON_INTERCEPT_FUNCTION(sigaction_symname)
diff --git a/compiler-rt/test/msan/interception_sigaction_test.cpp b/compiler-rt/test/msan/interception_sigaction_test.cpp
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/msan/interception_sigaction_test.cpp
@@ -0,0 +1,26 @@
+// RUN: %clangxx_msan -O0 -g %s -o %t
+// RUN: %t 2>&1 | FileCheck %s
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <signal.h>
+#include <string.h>
+
+extern "C" int __interceptor_sigaction(int signum, const struct sigaction *act, struct sigaction *oldact);
+extern "C" int sigaction(int signum, const struct sigaction *act, struct sigaction *oldact) {
+  write(2, "sigaction call\n", sizeof("sigaction call\n") - 1);
+  return __interceptor_sigaction(signum, act, oldact);
+}
+
+int main() {
+  struct sigaction oldact;
+  sigaction(11, nullptr, &oldact);
+  for (int i = 0; i < sizeof(oldact); ++i) {
+    if (oldact.sa_handler || oldact.sa_sigaction) {
+      write(2, "oldact filled\n", sizeof("oldact filled\n") - 1);
+    }
+  }
+  return 0;
+  // CHECK: sigaction call
+  // CHECK: oldact filled
+}