diff --git a/lib/Support/Process.cpp b/lib/Support/Process.cpp
index 1360842753d..d5168f03a6d 100644
--- a/lib/Support/Process.cpp
+++ b/lib/Support/Process.cpp
@@ -12,11 +12,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Config/config.h"
-#if LLVM_ON_WIN32
-  // This define makes stdlib.h declare the rand_s function.
-#define _CRT_RAND_S
-#include <stdlib.h>
-#endif
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Process.h"
 
diff --git a/lib/Support/Windows/Process.inc b/lib/Support/Windows/Process.inc
index 62b6da0cb1b..a0e3bc413a3 100644
--- a/lib/Support/Windows/Process.inc
+++ b/lib/Support/Windows/Process.inc
@@ -362,8 +362,15 @@ const char *Process::ResetColor() {
 }
 
 unsigned Process::GetRandomNumber() {
-  unsigned int result;
-  const int ec = rand_s(&result);
-  assert(ec == 0 && "rand_s failed");
-  return result;
+  HCRYPTPROV HCPC;
+  if (!::CryptAcquireContextW(&HCPC, NULL, NULL, PROV_RSA_FULL,
+                              CRYPT_VERIFYCONTEXT))
+    assert(false && "Could not acquire a cryptographic context");
+
+  ScopedCryptContext CryptoProvider(HCPC);
+  unsigned Ret;
+  if (!::CryptGenRandom(CryptoProvider, sizeof(Ret),
+                        reinterpret_cast<BYTE *>(&Ret)))
+    assert(false && "Could not generate a random number");
+  return Ret;
 }