Index: lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
===================================================================
--- lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
+++ lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
@@ -1483,6 +1483,7 @@
     case TYPE_MM64:                                       \
       return prefix##_MM0 + (index & 0x7);                \
     case TYPE_SEGMENTREG:                                 \
+      index = regFromModRM(insn->modRM);                  \
       if (index > 5)                                      \
         *valid = 0;                                       \
       return prefix##_ES + index;                         \
Index: test/MC/Disassembler/X86/x86-64.txt
===================================================================
--- test/MC/Disassembler/X86/x86-64.txt
+++ test/MC/Disassembler/X86/x86-64.txt
@@ -486,3 +486,9 @@
 
 # CHECK: nopq %rax
 0x48 0x0f 0x1f 0xC0
+
+# CHECK: movq    %rdx, %cs
+0x4c 0x8e 0xca
+
+# CHECK: movq    %rdx, %cs
+0x48 0x8e 0xca