diff --git a/lib/Target/X86/X86.td b/lib/Target/X86/X86.td
index e310f2676c5..e15512db23a 100644
--- a/lib/Target/X86/X86.td
+++ b/lib/Target/X86/X86.td
@@ -114,7 +114,7 @@ def X86InstrInfo : InstrInfo {
                        7,
                        11,
                        13,
-                       17];
+                       16];
 }
 
 // The X86 target supports two different syntaxes for emitting machine code.
diff --git a/lib/Target/X86/X86InstrInfo.h b/lib/Target/X86/X86InstrInfo.h
index 654a4334cfa..d6dfae14e6b 100644
--- a/lib/Target/X86/X86InstrInfo.h
+++ b/lib/Target/X86/X86InstrInfo.h
@@ -120,7 +120,7 @@ namespace X86II {
     // This two-bit field describes the size of an immediate operand.  Zero is
     // unused so that we can tell if we forgot to set a value.
     ImmShift = 11,
-    ImmMask  = 7 << ImmShift,
+    ImmMask  = 3 << ImmShift,
     Imm8     = 1 << ImmShift,
     Imm16    = 2 << ImmShift,
     Imm32    = 3 << ImmShift,
@@ -161,8 +161,7 @@ namespace X86II {
     // SpecialFP - Special instruction forms.  Dispatch by opcode explicitly.
     SpecialFP  = 7 << FPTypeShift,
 
-    // Bit 15 is unused.
-    OpcodeShift   = 17,
+    OpcodeShift   = 16,
     OpcodeMask    = 0xFF << OpcodeShift,
     // Bits 25 -> 31 are unused
   };