diff --git a/llvm/lib/Support/Unix/Signals.inc b/llvm/lib/Support/Unix/Signals.inc
--- a/llvm/lib/Support/Unix/Signals.inc
+++ b/llvm/lib/Support/Unix/Signals.inc
@@ -252,10 +252,13 @@
 
   stack_t AltStack = {};
   AltStack.ss_sp = static_cast<char *>(safe_malloc(AltStackSize));
-  NewAltStackPointer = AltStack.ss_sp; // Save to avoid reporting a leak.
   AltStack.ss_size = AltStackSize;
-  if (sigaltstack(&AltStack, &OldAltStack) != 0)
+  if (sigaltstack(&AltStack, &OldAltStack) != 0) {
     free(AltStack.ss_sp);
+  } else {
+    free(NewAltStackPointer);
+    NewAltStackPointer = AltStack.ss_sp; // Save to avoid reporting a leak.
+  }
 }
 #else
 static void CreateSigAltStack() {}