diff --git a/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp b/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
index 122204ae75c..30c56061b93 100644
--- a/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
+++ b/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
@@ -446,6 +446,7 @@ void X86MCCodeEmitter::EmitVEXOpcodePrefix(uint64_t TSFlags, unsigned &CurByte,
                                            raw_ostream &OS) const {
   bool HasVEX_4V = (TSFlags >> X86II::VEXShift) & X86II::VEX_4V;
   bool HasVEX_4VOp3 = (TSFlags >> X86II::VEXShift) & X86II::VEX_4VOp3;
+  bool HasMemOp4 = (TSFlags >> X86II::VEXShift) & X86II::MemOp4;
 
   // VEX_R: opcode externsion equivalent to REX.R in
   // 1's complement (inverted) form
@@ -650,12 +651,19 @@ void X86MCCodeEmitter::EmitVEXOpcodePrefix(uint64_t TSFlags, unsigned &CurByte,
     //  dst(ModR/M), src1(ModR/M)
     //  dst(ModR/M), src1(ModR/M), imm8
     //
+    //  FMA4:
+    //  dst(ModR/M.reg), src1(VEX_4V), src2(ModR/M), src3(VEX_I8IMM)
+    //  dst(ModR/M.reg), src1(VEX_4V), src2(VEX_I8IMM), src3(ModR/M),
     if (X86II::isX86_64ExtendedReg(MI.getOperand(CurOp).getReg()))
       VEX_R = 0x0;
     CurOp++;
 
     if (HasVEX_4V)
       VEX_4V = getVEXRegisterEncoding(MI, CurOp++);
+
+    if (HasMemOp4) // Skip second register source (encoded in I8IMM)
+      CurOp++;
+
     if (X86II::isX86_64ExtendedReg(MI.getOperand(CurOp).getReg()))
       VEX_B = 0x0;
     CurOp++;
diff --git a/lib/Target/X86/X86CodeEmitter.cpp b/lib/Target/X86/X86CodeEmitter.cpp
index ece38aa3466..a6bb2a74261 100644
--- a/lib/Target/X86/X86CodeEmitter.cpp
+++ b/lib/Target/X86/X86CodeEmitter.cpp
@@ -816,6 +816,7 @@ void Emitter<CodeEmitter>::emitVEXOpcodePrefix(uint64_t TSFlags,
                                                const MCInstrDesc *Desc) const {
   bool HasVEX_4V = (TSFlags >> X86II::VEXShift) & X86II::VEX_4V;
   bool HasVEX_4VOp3 = (TSFlags >> X86II::VEXShift) & X86II::VEX_4VOp3;
+  bool HasMemOp4 = (TSFlags >> X86II::VEXShift) & X86II::MemOp4;
 
   // VEX_R: opcode externsion equivalent to REX.R in
   // 1's complement (inverted) form
@@ -1032,6 +1033,10 @@ void Emitter<CodeEmitter>::emitVEXOpcodePrefix(uint64_t TSFlags,
 
       if (HasVEX_4V)
         VEX_4V = getVEXRegisterEncoding(MI, CurOp++);
+
+      if (MemOp4) // Skip second register source (encoded in I8IMM)
+        CurOp++;
+
       if (X86II::isX86_64ExtendedReg(MI.getOperand(CurOp).getReg()))
         VEX_B = 0x0;
       CurOp++;
diff --git a/test/MC/X86/x86_64-fma4-encoding.s b/test/MC/X86/x86_64-fma4-encoding.s
index f7ee351ab51..c9bd954e904 100644
--- a/test/MC/X86/x86_64-fma4-encoding.s
+++ b/test/MC/X86/x86_64-fma4-encoding.s
@@ -25,6 +25,10 @@
 // CHECK: encoding: [0xc4,0xe3,0xf9,0x6b,0xc2,0x10]
           vfmaddsd   %xmm2, %xmm1, %xmm0, %xmm0
 
+// CHECK: vfmaddsd   %xmm10, %xmm1, %xmm0, %xmm0
+// CHECK: encoding: [0xc4,0xc3,0xf9,0x6b,0xc2,0x10]
+          vfmaddsd   %xmm10, %xmm1, %xmm0, %xmm0
+
 // CHECK: vfmaddps  (%rcx), %xmm1, %xmm0, %xmm0
 // CHECK: encoding: [0xc4,0xe3,0xf9,0x68,0x01,0x10]
           vfmaddps  (%rcx), %xmm1, %xmm0, %xmm0