diff --git a/lib/Target/X86/X86InstrSSE.td b/lib/Target/X86/X86InstrSSE.td
index e8bbcb31a0a..66daddbb78e 100644
--- a/lib/Target/X86/X86InstrSSE.td
+++ b/lib/Target/X86/X86InstrSSE.td
@@ -341,6 +341,14 @@ def FsANDNPDrm : PDI<0x55, MRMSrcMem, (ops FR64:$dst, FR64:$src1, f128mem:$src2)
 // SSE packed FP Instructions
 //===----------------------------------------------------------------------===//
 
+// Some 'special' instructions
+def IMPLICIT_DEF_VR128 : I<0, Pseudo, (ops VR128:$dst),
+                           "#IMPLICIT_DEF $dst",
+                           [(set VR128:$dst, (v4f32 (undef)))]>,
+                         Requires<[HasSSE1]>;
+
+def : Pat<(v2f64 (undef)), (IMPLICIT_DEF_VR128)>, Requires<[HasSSE2]>;
+
 // Move Instructions
 def MOVAPSrr : PSI<0x28, MRMSrcReg, (ops VR128:$dst, VR128:$src),
                    "movaps {$src, $dst|$dst, $src}", []>;
@@ -686,6 +694,19 @@ def UNPCKLPDrm : PDI<0x14, MRMSrcMem,
 // SSE integer instructions
 //===----------------------------------------------------------------------===//
 
+// Some 'special' instructions
+def IMPLICIT_DEF_VR64 : I<0, Pseudo, (ops VR64:$dst),
+                          "#IMPLICIT_DEF $dst",
+                          [(set VR64:$dst, (v8i8 (undef)))]>,
+                        Requires<[HasMMX]>;
+
+def : Pat<(v4i16 (undef)), (IMPLICIT_DEF_VR64)>,  Requires<[HasMMX]>;
+def : Pat<(v2i32 (undef)), (IMPLICIT_DEF_VR64)>,  Requires<[HasMMX]>;
+def : Pat<(v16i8 (undef)), (IMPLICIT_DEF_VR128)>, Requires<[HasSSE2]>;
+def : Pat<(v8i16 (undef)), (IMPLICIT_DEF_VR128)>, Requires<[HasSSE2]>;
+def : Pat<(v4i32 (undef)), (IMPLICIT_DEF_VR128)>, Requires<[HasSSE2]>;
+def : Pat<(v2i64 (undef)), (IMPLICIT_DEF_VR128)>, Requires<[HasSSE2]>;
+
 // Move Instructions
 def MOVD128rr : PDI<0x6E, MRMSrcReg, (ops VR128:$dst, R32:$src),
                   "movd {$src, $dst|$dst, $src}", []>;