Index: include/llvm/IR/InlineAsm.h
===================================================================
--- include/llvm/IR/InlineAsm.h
+++ include/llvm/IR/InlineAsm.h
@@ -239,6 +239,7 @@
     // constraint codes for all targets.
     Constraint_Unknown = 0,
     Constraint_es,
+    Constraint_i,
     Constraint_m,
     Constraint_o,
     Constraint_v,
@@ -246,6 +247,7 @@
     Constraint_R,
     Constraint_S,
     Constraint_T,
+    Constraint_X,
     Constraint_Um,
     Constraint_Un,
     Constraint_Uq,
Index: lib/Target/X86/X86ISelDAGToDAG.cpp
===================================================================
--- lib/Target/X86/X86ISelDAGToDAG.cpp
+++ lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -2818,10 +2818,16 @@
                              std::vector<SDValue> &OutOps) {
   SDValue Op0, Op1, Op2, Op3, Op4;
   switch (ConstraintID) {
+  default:
+    llvm_unreachable("Unexpected asm memory constraint");
+  case InlineAsm::Constraint_i:
+    // FIXME: It seems strange that 'i' is needed here since it's supposed to
+    //        be an immediate and not a memory constraint.
+    // Fallthrough.
   case InlineAsm::Constraint_o: // offsetable        ??
   case InlineAsm::Constraint_v: // not offsetable    ??
-  default: return true;
   case InlineAsm::Constraint_m: // memory
+  case InlineAsm::Constraint_X:
     if (!SelectAddr(nullptr, Op, Op0, Op1, Op2, Op3, Op4))
       return true;
     break;
Index: lib/Target/X86/X86ISelLowering.h
===================================================================
--- lib/Target/X86/X86ISelLowering.h
+++ lib/Target/X86/X86ISelLowering.h
@@ -697,8 +697,15 @@
 
     unsigned getInlineAsmMemConstraint(
         const std::string ConstraintCode) const override {
-      // FIXME: Map different constraints differently.
-      return InlineAsm::Constraint_m;
+      if (ConstraintCode == "i")
+        return InlineAsm::Constraint_i;
+      else if (ConstraintCode == "o")
+        return InlineAsm::Constraint_o;
+      else if (ConstraintCode == "v")
+        return InlineAsm::Constraint_v;
+      else if (ConstraintCode == "X")
+        return InlineAsm::Constraint_X;
+      return TargetLowering::getInlineAsmMemConstraint(ConstraintCode);
     }
 
     /// Given a physical register constraint