diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 5853b51..bdbc9bb 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -17692,6 +17692,7 @@
     { ISD::FP_TO_SINT,  MVT::v4i8, MVT::v4f32,  1 },
     { ISD::ZERO_EXTEND, MVT::v8i32, MVT::v8i1,  6 },
     { ISD::SIGN_EXTEND, MVT::v8i32, MVT::v8i1,  9 },
+    { ISD::TRUNCATE,    MVT::v8i32, MVT::v8i64, 3 },
   };
 
   if (ST.hasAVX()) {
diff --git a/test/Analysis/CostModel/X86/cast.ll b/test/Analysis/CostModel/X86/cast.ll
index 298d5c6..75c97a7 100644
--- a/test/Analysis/CostModel/X86/cast.ll
+++ b/test/Analysis/CostModel/X86/cast.ll
@@ -53,6 +53,9 @@
   ;CHECK: cost of 1 {{.*}} trunc
   %F = trunc <8 x i32> undef to <8 x i16>
 
+  ;CHECK: cost of 3 {{.*}} trunc
+  %G = trunc <8 x i64> undef to <8 x i32>
+
   ret i32 undef
 }