Index: clang/lib/CodeGen/CGExpr.cpp
===================================================================
--- clang/lib/CodeGen/CGExpr.cpp
+++ clang/lib/CodeGen/CGExpr.cpp
@@ -3936,10 +3936,44 @@
 
     // Propagate the alignment from the array itself to the result.
     QualType arrayType = Array->getType();
-    Addr = emitArraySubscriptGEP(
-        *this, ArrayLV.getAddress(*this), {CGM.getSize(CharUnits::Zero()), Idx},
-        E->getType(), !getLangOpts().isSignedOverflowDefined(), SignedIndices,
-        E->getExprLoc(), &arrayType, E->getBase());
+
+    Address ArrayLVAddr = ArrayLV.getAddress(*this);
+
+    if (!getLangOpts().isSignedOverflowDefined() && 
+        // ISO/IEC 9899:TC3, 6.5.6.8
+        (getLangOpts().C99 || getLangOpts().CPlusPlus) &&
+        getContext().getAsConstantArrayType(arrayType)) {
+      auto *CAT = getContext().getAsConstantArrayType(arrayType);
+      uint64_t BoundedRegionSize = (Idx->getType()->getScalarSizeInBits() / 8) * 
+          CAT->getSize().getZExtValue();
+
+      Address BeginOff = emitArraySubscriptGEP(
+          *this, ArrayLVAddr, 
+          {CGM.getSize(CharUnits::Zero()), CGM.getSize(CharUnits::Zero())},
+          E->getType(), !getLangOpts().isSignedOverflowDefined(), SignedIndices,
+          E->getExprLoc(), &arrayType, E->getBase());
+
+      llvm::Function *F = CGM.getIntrinsic(llvm::Intrinsic::memory_region_decl, 
+          BeginOff.getPointer()->getType());
+      llvm::Value *Call = Builder.CreateCall(F,
+          {BeginOff.getPointer(), 
+          llvm::ConstantInt::get(Int64Ty, 0), 
+          llvm::ConstantInt::get(Int64Ty, BoundedRegionSize)},
+          "arrayidx.bounded");
+      Address RetAddr(Call, BeginOff.getElementType(), 
+          ArrayLVAddr.getAlignment());
+
+      Addr = emitArraySubscriptGEP(
+          *this, RetAddr, {Idx},
+          E->getType(), !getLangOpts().isSignedOverflowDefined(), SignedIndices,
+          E->getExprLoc(), &arrayType, E->getBase());
+    } else {
+      Addr = emitArraySubscriptGEP(
+          *this, ArrayLVAddr, {CGM.getSize(CharUnits::Zero()), Idx},
+          E->getType(), !getLangOpts().isSignedOverflowDefined(), SignedIndices,
+          E->getExprLoc(), &arrayType, E->getBase());
+    }
+        
     EltBaseInfo = ArrayLV.getBaseInfo();
     EltTBAAInfo = CGM.getTBAAInfoForSubobject(ArrayLV, E->getType());
   } else {