diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -3179,6 +3179,10 @@
   if (isa<UndefValue>(V))
     return UndefInt8;
 
+  const uint64_t Size = DL.getTypeStoreSize(V->getType());
+  if (!Size)
+    return UndefInt8;
+
   Constant *C = dyn_cast<Constant>(V);
   if (!C) {
     // Conceptually, we could handle things like:
diff --git a/llvm/unittests/Analysis/ValueTrackingTest.cpp b/llvm/unittests/Analysis/ValueTrackingTest.cpp
--- a/llvm/unittests/Analysis/ValueTrackingTest.cpp
+++ b/llvm/unittests/Analysis/ValueTrackingTest.cpp
@@ -810,7 +810,7 @@
         "i16* inttoptr (i96 -1 to i16*)",
     },
     {
-        "i8 0",
+        "i8 undef",
         "[0 x i8] zeroinitializer",
     },
     {
@@ -818,7 +818,7 @@
         "[0 x i8] undef",
     },
     {
-        "i8 0",
+        "i8 undef",
         "[5 x [0 x i8]] zeroinitializer",
     },
     {
@@ -900,7 +900,7 @@
         "[2 x i16] [i16 -21836, i16 -21846]]",
     },
     {
-        "i8 0",
+        "i8 undef",
         "{ } zeroinitializer",
     },
     {
@@ -908,7 +908,7 @@
         "{ } undef",
     },
     {
-        "i8 0",
+        "i8 undef",
         "{ {}, {} } zeroinitializer",
     },
     {