Index: lib/Target/X86/X86InstrInfo.td
===================================================================
--- lib/Target/X86/X86InstrInfo.td
+++ lib/Target/X86/X86InstrInfo.td
@@ -1371,52 +1371,52 @@
 def BSF16rr  : I<0xBC, MRMSrcReg, (outs GR16:$dst), (ins GR16:$src),
                  "bsf{w}\t{$src, $dst|$dst, $src}",
                  [(set GR16:$dst, EFLAGS, (X86bsf GR16:$src))]>,
-                  PS, OpSize16, Sched<[WriteBitScan]>;
+                  PS, OpSize16, Sched<[WriteBitScanForward]>;
 def BSF16rm  : I<0xBC, MRMSrcMem, (outs GR16:$dst), (ins i16mem:$src),
                  "bsf{w}\t{$src, $dst|$dst, $src}",
                  [(set GR16:$dst, EFLAGS, (X86bsf (loadi16 addr:$src)))]>,
-                 PS, OpSize16, Sched<[WriteBitScanLd]>;
+                 PS, OpSize16, Sched<[WriteBitScanForwardLd]>;
 def BSF32rr  : I<0xBC, MRMSrcReg, (outs GR32:$dst), (ins GR32:$src),
                  "bsf{l}\t{$src, $dst|$dst, $src}",
                  [(set GR32:$dst, EFLAGS, (X86bsf GR32:$src))]>,
-                 PS, OpSize32, Sched<[WriteBitScan]>;
+                 PS, OpSize32, Sched<[WriteBitScanForward]>;
 def BSF32rm  : I<0xBC, MRMSrcMem, (outs GR32:$dst), (ins i32mem:$src),
                  "bsf{l}\t{$src, $dst|$dst, $src}",
                  [(set GR32:$dst, EFLAGS, (X86bsf (loadi32 addr:$src)))]>,
-                 PS, OpSize32, Sched<[WriteBitScanLd]>;
+                 PS, OpSize32, Sched<[WriteBitScanForwardLd]>;
 def BSF64rr  : RI<0xBC, MRMSrcReg, (outs GR64:$dst), (ins GR64:$src),
                   "bsf{q}\t{$src, $dst|$dst, $src}",
                   [(set GR64:$dst, EFLAGS, (X86bsf GR64:$src))]>,
-                  PS, Sched<[WriteBitScan]>;
+                  PS, Sched<[WriteBitScanForward]>;
 def BSF64rm  : RI<0xBC, MRMSrcMem, (outs GR64:$dst), (ins i64mem:$src),
                   "bsf{q}\t{$src, $dst|$dst, $src}",
                   [(set GR64:$dst, EFLAGS, (X86bsf (loadi64 addr:$src)))]>,
-                  PS, Sched<[WriteBitScanLd]>;
+                  PS, Sched<[WriteBitScanForwardLd]>;
 
 def BSR16rr  : I<0xBD, MRMSrcReg, (outs GR16:$dst), (ins GR16:$src),
                  "bsr{w}\t{$src, $dst|$dst, $src}",
                  [(set GR16:$dst, EFLAGS, (X86bsr GR16:$src))]>,
-                 PS, OpSize16, Sched<[WriteBitScan]>;
+                 PS, OpSize16, Sched<[WriteBitScanReverse]>;
 def BSR16rm  : I<0xBD, MRMSrcMem, (outs GR16:$dst), (ins i16mem:$src),
                  "bsr{w}\t{$src, $dst|$dst, $src}",
                  [(set GR16:$dst, EFLAGS, (X86bsr (loadi16 addr:$src)))]>,
-                 PS, OpSize16, Sched<[WriteBitScanLd]>;
+                 PS, OpSize16, Sched<[WriteBitScanReverseLd]>;
 def BSR32rr  : I<0xBD, MRMSrcReg, (outs GR32:$dst), (ins GR32:$src),
                  "bsr{l}\t{$src, $dst|$dst, $src}",
                  [(set GR32:$dst, EFLAGS, (X86bsr GR32:$src))]>,
-                 PS, OpSize32, Sched<[WriteBitScan]>;
+                 PS, OpSize32, Sched<[WriteBitScanReverse]>;
 def BSR32rm  : I<0xBD, MRMSrcMem, (outs GR32:$dst), (ins i32mem:$src),
                  "bsr{l}\t{$src, $dst|$dst, $src}",
                  [(set GR32:$dst, EFLAGS, (X86bsr (loadi32 addr:$src)))]>,
-                 PS, OpSize32, Sched<[WriteBitScanLd]>;
+                 PS, OpSize32, Sched<[WriteBitScanReverseLd]>;
 def BSR64rr  : RI<0xBD, MRMSrcReg, (outs GR64:$dst), (ins GR64:$src),
                   "bsr{q}\t{$src, $dst|$dst, $src}",
                   [(set GR64:$dst, EFLAGS, (X86bsr GR64:$src))]>,
-                  PS, Sched<[WriteBitScan]>;
+                  PS, Sched<[WriteBitScanReverse]>;
 def BSR64rm  : RI<0xBD, MRMSrcMem, (outs GR64:$dst), (ins i64mem:$src),
                   "bsr{q}\t{$src, $dst|$dst, $src}",
                   [(set GR64:$dst, EFLAGS, (X86bsr (loadi64 addr:$src)))]>,
-                  PS, Sched<[WriteBitScanLd]>;
+                  PS, Sched<[WriteBitScanReverseLd]>;
 } // Defs = [EFLAGS]
 
 let SchedRW = [WriteMicrocoded] in {
Index: lib/Target/X86/X86SchedBroadwell.td
===================================================================
--- lib/Target/X86/X86SchedBroadwell.td
+++ lib/Target/X86/X86SchedBroadwell.td
@@ -137,10 +137,11 @@
 def  : WriteRes<WriteLAHFSAHF, [BWPort06]>;
 
 // Bit counts.
-defm : BWWriteResPair<WriteBitScan, [BWPort1], 3>;
-defm : BWWriteResPair<WriteLZCNT,   [BWPort1], 3>;
-defm : BWWriteResPair<WriteTZCNT,   [BWPort1], 3>;
-defm : BWWriteResPair<WritePOPCNT,  [BWPort1], 3>;
+defm : BWWriteResPair<WriteBitScanForward, [BWPort1], 3>;
+defm : BWWriteResPair<WriteBitScanReverse, [BWPort1], 3>;
+defm : BWWriteResPair<WriteLZCNT,          [BWPort1], 3>;
+defm : BWWriteResPair<WriteTZCNT,          [BWPort1], 3>;
+defm : BWWriteResPair<WritePOPCNT,         [BWPort1], 3>;
 
 // Integer shifts and rotates.
 defm : BWWriteResPair<WriteShift, [BWPort06],  1>;
Index: lib/Target/X86/X86SchedHaswell.td
===================================================================
--- lib/Target/X86/X86SchedHaswell.td
+++ lib/Target/X86/X86SchedHaswell.td
@@ -143,10 +143,11 @@
 def : WriteRes<WriteLEA, [HWPort15]>;
 
 // Bit counts.
-defm : HWWriteResPair<WriteBitScan, [HWPort1], 3>;
-defm : HWWriteResPair<WriteLZCNT,   [HWPort1], 3>;
-defm : HWWriteResPair<WriteTZCNT,   [HWPort1], 3>;
-defm : HWWriteResPair<WritePOPCNT,  [HWPort1], 3>;
+defm : HWWriteResPair<WriteBitScanForward, [HWPort1], 3>;
+defm : HWWriteResPair<WriteBitScanReverse, [HWPort1], 3>;
+defm : HWWriteResPair<WriteLZCNT,          [HWPort1], 3>;
+defm : HWWriteResPair<WriteTZCNT,          [HWPort1], 3>;
+defm : HWWriteResPair<WritePOPCNT,         [HWPort1], 3>;
 
 // BMI1 BEXTR, BMI2 BZHI
 defm : HWWriteResPair<WriteBEXTR, [HWPort06,HWPort15], 2, [1,1], 2>;
Index: lib/Target/X86/X86SchedSandyBridge.td
===================================================================
--- lib/Target/X86/X86SchedSandyBridge.td
+++ lib/Target/X86/X86SchedSandyBridge.td
@@ -142,10 +142,11 @@
 def : WriteRes<WriteLEA, [SBPort01]>;
 
 // Bit counts.
-defm : SBWriteResPair<WriteBitScan, [SBPort1], 3, [1], 1, 5>;
-defm : SBWriteResPair<WriteLZCNT,   [SBPort1], 3, [1], 1, 5>;
-defm : SBWriteResPair<WriteTZCNT,   [SBPort1], 3, [1], 1, 5>;
-defm : SBWriteResPair<WritePOPCNT,  [SBPort1], 3, [1], 1, 6>;
+defm : SBWriteResPair<WriteBitScanForward, [SBPort1], 3, [1], 1, 5>;
+defm : SBWriteResPair<WriteBitScanReverse, [SBPort1], 3, [1], 1, 5>;
+defm : SBWriteResPair<WriteLZCNT,          [SBPort1], 3, [1], 1, 5>;
+defm : SBWriteResPair<WriteTZCNT,          [SBPort1], 3, [1], 1, 5>;
+defm : SBWriteResPair<WritePOPCNT,         [SBPort1], 3, [1], 1, 6>;
 
 // BMI1 BEXTR, BMI2 BZHI
 // NOTE: These don't exist on Sandy Bridge. Ports are guesses.
Index: lib/Target/X86/X86SchedSkylakeClient.td
===================================================================
--- lib/Target/X86/X86SchedSkylakeClient.td
+++ lib/Target/X86/X86SchedSkylakeClient.td
@@ -135,10 +135,11 @@
 def  : WriteRes<WriteLAHFSAHF, [SKLPort06]>;
 
 // Bit counts.
-defm : SKLWriteResPair<WriteBitScan, [SKLPort1], 3>;
-defm : SKLWriteResPair<WriteLZCNT,   [SKLPort1], 3>;
-defm : SKLWriteResPair<WriteTZCNT,   [SKLPort1], 3>;
-defm : SKLWriteResPair<WritePOPCNT,  [SKLPort1], 3>;
+defm : SKLWriteResPair<WriteBitScanForward, [SKLPort1], 3>;
+defm : SKLWriteResPair<WriteBitScanReverse, [SKLPort1], 3>;
+defm : SKLWriteResPair<WriteLZCNT,          [SKLPort1], 3>;
+defm : SKLWriteResPair<WriteTZCNT,          [SKLPort1], 3>;
+defm : SKLWriteResPair<WritePOPCNT,         [SKLPort1], 3>;
 
 // Integer shifts and rotates.
 defm : SKLWriteResPair<WriteShift, [SKLPort06],  1>;
Index: lib/Target/X86/X86SchedSkylakeServer.td
===================================================================
--- lib/Target/X86/X86SchedSkylakeServer.td
+++ lib/Target/X86/X86SchedSkylakeServer.td
@@ -138,10 +138,11 @@
 defm : SKXWriteResPair<WriteShift, [SKXPort06],  1>;
 
 // Bit counts.
-defm : SKXWriteResPair<WriteBitScan, [SKXPort1], 3>;
-defm : SKXWriteResPair<WriteLZCNT,   [SKXPort1], 3>;
-defm : SKXWriteResPair<WriteTZCNT,   [SKXPort1], 3>;
-defm : SKXWriteResPair<WritePOPCNT,  [SKXPort1], 3>;
+defm : SKXWriteResPair<WriteBitScanForward, [SKXPort1], 3>;
+defm : SKXWriteResPair<WriteBitScanReverse, [SKXPort1], 3>;
+defm : SKXWriteResPair<WriteLZCNT,          [SKXPort1], 3>;
+defm : SKXWriteResPair<WriteTZCNT,          [SKXPort1], 3>;
+defm : SKXWriteResPair<WritePOPCNT,         [SKXPort1], 3>;
 
 // BMI1 BEXTR, BMI2 BZHI
 defm : SKXWriteResPair<WriteBEXTR, [SKXPort06,SKXPort15], 2, [1,1], 2>;
Index: lib/Target/X86/X86Schedule.td
===================================================================
--- lib/Target/X86/X86Schedule.td
+++ lib/Target/X86/X86Schedule.td
@@ -128,7 +128,8 @@
 defm WriteIDiv32 : X86SchedWritePair;
 defm WriteIDiv64 : X86SchedWritePair;
 
-defm WriteBitScan : X86SchedWritePair; // Bit scan forward/reverse.
+defm WriteBitScanForward : X86SchedWritePair; // Bit scan forward.
+defm WriteBitScanReverse : X86SchedWritePair; // Bit scan reverse.
 defm WritePOPCNT : X86SchedWritePair; // Bit population count.
 defm WriteLZCNT : X86SchedWritePair; // Leading zero count.
 defm WriteTZCNT : X86SchedWritePair; // Trailing zero count.
Index: lib/Target/X86/X86ScheduleAtom.td
===================================================================
--- lib/Target/X86/X86ScheduleAtom.td
+++ lib/Target/X86/X86ScheduleAtom.td
@@ -131,7 +131,8 @@
                                          IMUL64rmi8, IMUL64rmi32)>;
 
 // Bit counts.
-defm : AtomWriteResPair<WriteBitScan, [AtomPort01], [AtomPort01], 16, 16, [16], [16]>;
+defm : AtomWriteResPair<WriteBitScanForward, [AtomPort01], [AtomPort01], 16, 16, [16], [16]>;
+defm : AtomWriteResPair<WriteBitScanReverse, [AtomPort01], [AtomPort01], 16, 16, [16], [16]>;
 defm : X86WriteResPairUnsupported<WritePOPCNT>;
 defm : X86WriteResPairUnsupported<WriteLZCNT>;
 defm : X86WriteResPairUnsupported<WriteTZCNT>;
Index: lib/Target/X86/X86ScheduleBtVer2.td
===================================================================
--- lib/Target/X86/X86ScheduleBtVer2.td
+++ lib/Target/X86/X86ScheduleBtVer2.td
@@ -184,10 +184,11 @@
 def : WriteRes<WriteLEA, [JALU01]>;
 
 // Bit counts.
-defm : JWriteResIntPair<WriteBitScan, [JALU01], 5, [4], 8>;
-defm : JWriteResIntPair<WritePOPCNT,  [JALU01], 1>;
-defm : JWriteResIntPair<WriteLZCNT,   [JALU01], 1>;
-defm : JWriteResIntPair<WriteTZCNT,   [JALU01], 2, [2]>;
+defm : JWriteResIntPair<WriteBitScanForward, [JALU01], 5, [4], 8>;
+defm : JWriteResIntPair<WriteBitScanReverse, [JALU01], 5, [4], 8>;
+defm : JWriteResIntPair<WritePOPCNT,         [JALU01], 1>;
+defm : JWriteResIntPair<WriteLZCNT,          [JALU01], 1>;
+defm : JWriteResIntPair<WriteTZCNT,          [JALU01], 2, [2]>;
 
 // BMI1 BEXTR, BMI2 BZHI
 defm : JWriteResIntPair<WriteBEXTR, [JALU01], 1>;
Index: lib/Target/X86/X86ScheduleSLM.td
===================================================================
--- lib/Target/X86/X86ScheduleSLM.td
+++ lib/Target/X86/X86ScheduleSLM.td
@@ -117,10 +117,11 @@
 def : WriteRes<WriteLEA, [SLM_IEC_RSV1]>;
 
 // Bit counts.
-defm : SLMWriteResPair<WriteBitScan, [SLM_IEC_RSV01], 10, [20], 10>;
-defm : SLMWriteResPair<WriteLZCNT,   [SLM_IEC_RSV0], 3>;
-defm : SLMWriteResPair<WriteTZCNT,   [SLM_IEC_RSV0], 3>;
-defm : SLMWriteResPair<WritePOPCNT,  [SLM_IEC_RSV0], 3>;
+defm : SLMWriteResPair<WriteBitScanForward, [SLM_IEC_RSV01], 10, [20], 10>;
+defm : SLMWriteResPair<WriteBitScanReverse, [SLM_IEC_RSV01], 10, [20], 10>;
+defm : SLMWriteResPair<WriteLZCNT,          [SLM_IEC_RSV0], 3>;
+defm : SLMWriteResPair<WriteTZCNT,          [SLM_IEC_RSV0], 3>;
+defm : SLMWriteResPair<WritePOPCNT,         [SLM_IEC_RSV0], 3>;
 
 // BMI1 BEXTR, BMI2 BZHI
 defm : X86WriteResPairUnsupported<WriteBEXTR>;
Index: lib/Target/X86/X86ScheduleZnver1.td
===================================================================
--- lib/Target/X86/X86ScheduleZnver1.td
+++ lib/Target/X86/X86ScheduleZnver1.td
@@ -190,10 +190,11 @@
 defm : X86WriteRes<WriteLAHFSAHF, [ZnALU], 2, [1], 2>;
 
 // Bit counts.
-defm : ZnWriteResPair<WriteBitScan, [ZnALU], 3>;
-defm : ZnWriteResPair<WriteLZCNT,   [ZnALU], 2>;
-defm : ZnWriteResPair<WriteTZCNT,   [ZnALU], 2>;
-defm : ZnWriteResPair<WritePOPCNT,  [ZnALU], 1>;
+defm : ZnWriteResPair<WriteBitScanForward, [ZnALU], 3>;
+defm : ZnWriteResPair<WriteBitScanReverse, [ZnALU], 3>;
+defm : ZnWriteResPair<WriteLZCNT,          [ZnALU], 2>;
+defm : ZnWriteResPair<WriteTZCNT,          [ZnALU], 2>;
+defm : ZnWriteResPair<WritePOPCNT,         [ZnALU], 1>;
 
 // Treat misc copies as a move.
 def : InstRW<[WriteMove], (instrs COPY)>;