diff --git a/third_party/llvm-10.0/llvm/lib/CodeGen/GlobalISel/LegalityPredicates.cpp b/third_party/llvm-10.0/llvm/lib/CodeGen/GlobalISel/LegalityPredicates.cpp
index 601d50e..f0f8c2d 100644
--- a/third_party/llvm-10.0/llvm/lib/CodeGen/GlobalISel/LegalityPredicates.cpp
+++ b/third_party/llvm-10.0/llvm/lib/CodeGen/GlobalISel/LegalityPredicates.cpp
@@ -10,6 +10,17 @@
 //
 //===----------------------------------------------------------------------===//
 
+// Enable optimizations to work around MSVC debug mode bug in 32-bit:
+// https://developercommunity.visualstudio.com/content/problem/1179643/msvc-copies-overaligned-non-trivially-copyable-par.html
+// FIXME: Remove this when the issue is closed.
+#if defined(_MSC_VER) && !defined(__clang__) && defined(_M_IX86)
+// We have to disable runtime checks in order to enable optimizations. This is
+// done for the entire file because the problem is actually observed in STL
+// template functions.
+#pragma runtime_checks("", off)
+#pragma optimize("gs", on)
+#endif
+
 #include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
 
 using namespace llvm;