diff --git a/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp b/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
index d9766f5c157..606001d988a 100644
--- a/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
+++ b/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
@@ -1453,8 +1453,6 @@ static int readModRM(struct InternalInstruction* insn) {
         *valid = 0;                                       \
       return prefix##_ES + index;                         \
     case TYPE_DEBUGREG:                                   \
-      if (index > 7)                                      \
-        *valid = 0;                                       \
       return prefix##_DR0 + index;                        \
     case TYPE_CONTROLREG:                                 \
       return prefix##_CR0 + index;                        \
diff --git a/lib/Target/X86/Disassembler/X86DisassemblerDecoder.h b/lib/Target/X86/Disassembler/X86DisassemblerDecoder.h
index 46a74ab4e52..a79a923ac52 100644
--- a/lib/Target/X86/Disassembler/X86DisassemblerDecoder.h
+++ b/lib/Target/X86/Disassembler/X86DisassemblerDecoder.h
@@ -341,7 +341,15 @@ namespace X86Disassembler {
   ENTRY(DR4)        \
   ENTRY(DR5)        \
   ENTRY(DR6)        \
-  ENTRY(DR7)
+  ENTRY(DR7)        \
+  ENTRY(DR8)        \
+  ENTRY(DR9)        \
+  ENTRY(DR10)       \
+  ENTRY(DR11)       \
+  ENTRY(DR12)       \
+  ENTRY(DR13)       \
+  ENTRY(DR14)       \
+  ENTRY(DR15)
 
 #define REGS_CONTROL  \
   ENTRY(CR0)          \
diff --git a/lib/Target/X86/X86RegisterInfo.td b/lib/Target/X86/X86RegisterInfo.td
index 311a7178149..30cd09a5a2f 100644
--- a/lib/Target/X86/X86RegisterInfo.td
+++ b/lib/Target/X86/X86RegisterInfo.td
@@ -263,14 +263,22 @@ def FS : X86Reg<"fs", 4>;
 def GS : X86Reg<"gs", 5>;
 
 // Debug registers
-def DR0 : X86Reg<"dr0", 0>;
-def DR1 : X86Reg<"dr1", 1>;
-def DR2 : X86Reg<"dr2", 2>;
-def DR3 : X86Reg<"dr3", 3>;
-def DR4 : X86Reg<"dr4", 4>;
-def DR5 : X86Reg<"dr5", 5>;
-def DR6 : X86Reg<"dr6", 6>;
-def DR7 : X86Reg<"dr7", 7>;
+def DR0  : X86Reg<"dr0",   0>;
+def DR1  : X86Reg<"dr1",   1>;
+def DR2  : X86Reg<"dr2",   2>;
+def DR3  : X86Reg<"dr3",   3>;
+def DR4  : X86Reg<"dr4",   4>;
+def DR5  : X86Reg<"dr5",   5>;
+def DR6  : X86Reg<"dr6",   6>;
+def DR7  : X86Reg<"dr7",   7>;
+def DR8  : X86Reg<"dr8",   8>;
+def DR9  : X86Reg<"dr9",   9>;
+def DR10 : X86Reg<"dr10", 10>;
+def DR11 : X86Reg<"dr11", 11>;
+def DR12 : X86Reg<"dr12", 12>;
+def DR13 : X86Reg<"dr13", 13>;
+def DR14 : X86Reg<"dr14", 14>;
+def DR15 : X86Reg<"dr15", 15>;
 
 // Control registers
 def CR0  : X86Reg<"cr0",   0>;
diff --git a/test/MC/Disassembler/X86/prefixes.txt b/test/MC/Disassembler/X86/prefixes.txt
index 5f0a58c7437..ee0ba086618 100644
--- a/test/MC/Disassembler/X86/prefixes.txt
+++ b/test/MC/Disassembler/X86/prefixes.txt
@@ -58,6 +58,8 @@
 # Test that we can disassembler control registers above CR8
 # CHECK: movq %cr15, %rax
 0x44 0x0f 0x20 0xf8
+# CHECK: movq %dr15, %rax
+0x44 0x0f 0x21 0xf8
 
 # Test that MMX ignore REX.R and REX.B.
 # CHECK: movq %mm0, %mm1