Index: llvm/trunk/docs/CodeGenerator.rst
===================================================================
--- llvm/trunk/docs/CodeGenerator.rst
+++ llvm/trunk/docs/CodeGenerator.rst
@@ -2197,9 +2197,9 @@
 the specified segment.  LLVM address space 0 is the default address space, which
 includes the stack, and any unqualified memory accesses in a program.  Address
 spaces 1-255 are currently reserved for user-defined code.  The GS-segment is
-represented by address space 256, while the FS-segment is represented by address
-space 257. Other x86 segments have yet to be allocated address space
-numbers.
+represented by address space 256, the FS-segment is represented by address space
+257, and the SS-segment is represented by address space 258. Other x86 segments
+have yet to be allocated address space numbers.
 
 While these address spaces may seem similar to TLS via the ``thread_local``
 keyword, and often use the same underlying hardware, there are some fundamental
Index: llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp
===================================================================
--- llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -727,6 +727,8 @@
       case 257:
         AM.Segment = CurDAG->getRegister(X86::FS, MVT::i16);
         return false;
+      // Address space 258 is not handled here, because it is not used to
+      // address TLS areas.
       }
 
   return true;
@@ -1424,11 +1426,13 @@
     return false;
   X86ISelAddressMode AM;
   unsigned AddrSpace = Mgs->getPointerInfo().getAddrSpace();
-  // AddrSpace 256 -> GS, 257 -> FS.
+  // AddrSpace 256 -> GS, 257 -> FS, 258 -> SS.
   if (AddrSpace == 256)
     AM.Segment = CurDAG->getRegister(X86::GS, MVT::i16);
   if (AddrSpace == 257)
     AM.Segment = CurDAG->getRegister(X86::FS, MVT::i16);
+  if (AddrSpace == 258)
+    AM.Segment = CurDAG->getRegister(X86::SS, MVT::i16);
 
   SDLoc DL(N);
   Base = Mgs->getBasePtr();
@@ -1473,11 +1477,13 @@
       Parent->getOpcode() != X86ISD::EH_SJLJ_LONGJMP) { // longjmp
     unsigned AddrSpace =
       cast<MemSDNode>(Parent)->getPointerInfo().getAddrSpace();
-    // AddrSpace 256 -> GS, 257 -> FS.
+    // AddrSpace 256 -> GS, 257 -> FS, 258 -> SS.
     if (AddrSpace == 256)
       AM.Segment = CurDAG->getRegister(X86::GS, MVT::i16);
     if (AddrSpace == 257)
       AM.Segment = CurDAG->getRegister(X86::FS, MVT::i16);
+    if (AddrSpace == 258)
+      AM.Segment = CurDAG->getRegister(X86::SS, MVT::i16);
   }
 
   if (matchAddress(N, AM))