diff --git a/lib/IR/ConstantFold.cpp b/lib/IR/ConstantFold.cpp
index 9124c111935..b96d1540d71 100644
--- a/lib/IR/ConstantFold.cpp
+++ b/lib/IR/ConstantFold.cpp
@@ -674,6 +674,9 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V,
     }
     return nullptr;
   case Instruction::Trunc: {
+    if (V->getType()->isVectorTy())
+      return nullptr;
+
     uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
     if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
       return ConstantInt::get(V->getContext(),
diff --git a/test/Transforms/ConstProp/trunc_vec.ll b/test/Transforms/ConstProp/trunc_vec.ll
new file mode 100644
index 00000000000..99db329cdd2
--- /dev/null
+++ b/test/Transforms/ConstProp/trunc_vec.ll
@@ -0,0 +1,9 @@
+; RUN: opt -constprop < %s
+
+; Make sure we don't crash on this one
+
+define <8 x i8> @test_truc_vec() {
+  %x = bitcast <2 x i64> <i64 1, i64 2> to <8 x i16>
+  %y = trunc <8 x i16> %x to <8 x i8>
+  ret <8 x i8> %y
+}