Index: lib/Target/X86/X86InstrCompiler.td
===================================================================
--- lib/Target/X86/X86InstrCompiler.td
+++ lib/Target/X86/X86InstrCompiler.td
@@ -1798,6 +1798,37 @@
                         (i64 (IMPLICIT_DEF)), GR8:$src2, sub_8bit))>;
 }
 
+// If we have BMI2, we transform the
+//   x &  (-1 'logical shift' y)
+// into
+//   (x 'opposite logical shift' y) 'logical shift' y
+let Predicates = [HasBMI2] in {
+  multiclass bit_clean<RegisterClass RC, ValueType VT, PatFrag Load,
+                       PatFrag OrigShift, Instruction OuterShift,
+                       Instruction InnerShiftReg, Instruction InnerShiftMem> {
+    def : Pat<(and RC:$src1, (OrigShift -1, GR8:$src2)),
+              (OuterShift (InnerShiftReg $src1,
+                            (INSERT_SUBREG (VT (IMPLICIT_DEF)),
+                                           GR8:$src2, sub_8bit)),
+                          (INSERT_SUBREG (VT (IMPLICIT_DEF)),
+                                         GR8:$src2, sub_8bit))>;
+    def : Pat<(and (Load addr:$src1), (OrigShift -1, GR8:$src2)),
+              (OuterShift (InnerShiftMem addr:$src1,
+                            (INSERT_SUBREG (VT (IMPLICIT_DEF)),
+                                           GR8:$src2, sub_8bit)),
+                          (INSERT_SUBREG (VT (IMPLICIT_DEF)),
+                                         GR8:$src2, sub_8bit))>;
+  }
+
+  // x & (-1 >> y)  -->  x << y >> y   (clear y high bits)
+  defm : bit_clean<GR32, i32, loadi32,  srl_su, SHRX32rr,  SHLX32rr, SHLX32rm>;
+  defm : bit_clean<GR64, i64, loadi64,  srl_su, SHRX64rr,  SHLX64rr, SHLX64rm>;
+
+  // x & (-1 << y)  -->  x >> y << y   (clear y low  bits)
+  defm : bit_clean<GR32, i32, loadi32,  shl_su, SHLX32rr,  SHRX32rr, SHRX32rm>;
+  defm : bit_clean<GR64, i64, loadi64,  shl_su, SHLX64rr,  SHRX64rr, SHRX64rm>;
+}
+
 // Use BTR/BTS/BTC for clearing/setting/toggling a bit in a variable location.
 multiclass one_bit_patterns<RegisterClass RC, ValueType VT, Instruction BTR,
                             Instruction BTS, Instruction BTC,
Index: lib/Target/X86/X86InstrInfo.td
===================================================================
--- lib/Target/X86/X86InstrInfo.td
+++ lib/Target/X86/X86InstrInfo.td
@@ -1132,6 +1132,10 @@
 def srl_su : PatFrag<(ops node:$lhs, node:$rhs), (srl node:$lhs, node:$rhs), [{
   return N->hasOneUse();
 }]>;
+// An 'shl' node with a single use.
+def shl_su : PatFrag<(ops node:$lhs, node:$rhs), (shl node:$lhs, node:$rhs), [{
+  return N->hasOneUse();
+}]>;
 // An 'trunc' node with a single use.
 def trunc_su : PatFrag<(ops node:$src), (trunc node:$src), [{
   return N->hasOneUse();
Index: test/CodeGen/X86/clear-highbits.ll
===================================================================
--- test/CodeGen/X86/clear-highbits.ll
+++ test/CodeGen/X86/clear-highbits.ll
@@ -31,9 +31,8 @@
 ; X86-TRANSFORM-LABEL: clear_highbits32_c0:
 ; X86-TRANSFORM:       # %bb.0:
 ; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-TRANSFORM-NEXT:    movl $-1, %ecx
+; X86-TRANSFORM-NEXT:    shlxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-TRANSFORM-NEXT:    shrxl %eax, %ecx, %eax
-; X86-TRANSFORM-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-TRANSFORM-NEXT:    retl
 ;
 ; X64-NOTRANSFORM-LABEL: clear_highbits32_c0:
@@ -46,9 +45,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_highbits32_c0:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movl $-1, %eax
+; X64-TRANSFORM-NEXT:    shlxl %esi, %edi, %eax
 ; X64-TRANSFORM-NEXT:    shrxl %esi, %eax, %eax
-; X64-TRANSFORM-NEXT:    andl %edi, %eax
 ; X64-TRANSFORM-NEXT:    retq
   %mask = lshr i32 -1, %numhighbits
   %masked = and i32 %mask, %val
@@ -67,9 +65,8 @@
 ; X86-TRANSFORM-LABEL: clear_highbits32_c1_indexzext:
 ; X86-TRANSFORM:       # %bb.0:
 ; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-TRANSFORM-NEXT:    movl $-1, %ecx
+; X86-TRANSFORM-NEXT:    shlxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-TRANSFORM-NEXT:    shrxl %eax, %ecx, %eax
-; X86-TRANSFORM-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-TRANSFORM-NEXT:    retl
 ;
 ; X64-NOTRANSFORM-LABEL: clear_highbits32_c1_indexzext:
@@ -82,9 +79,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_highbits32_c1_indexzext:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movl $-1, %eax
+; X64-TRANSFORM-NEXT:    shlxl %esi, %edi, %eax
 ; X64-TRANSFORM-NEXT:    shrxl %esi, %eax, %eax
-; X64-TRANSFORM-NEXT:    andl %edi, %eax
 ; X64-TRANSFORM-NEXT:    retq
   %sh_prom = zext i8 %numhighbits to i32
   %mask = lshr i32 -1, %sh_prom
@@ -104,11 +100,10 @@
 ;
 ; X86-TRANSFORM-LABEL: clear_highbits32_c2_load:
 ; X86-TRANSFORM:       # %bb.0:
-; X86-TRANSFORM-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-TRANSFORM-NEXT:    movl $-1, %edx
-; X86-TRANSFORM-NEXT:    shrxl %eax, %edx, %eax
-; X86-TRANSFORM-NEXT:    andl (%ecx), %eax
+; X86-TRANSFORM-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %cl
+; X86-TRANSFORM-NEXT:    shlxl %ecx, (%eax), %eax
+; X86-TRANSFORM-NEXT:    shrxl %ecx, %eax, %eax
 ; X86-TRANSFORM-NEXT:    retl
 ;
 ; X64-NOTRANSFORM-LABEL: clear_highbits32_c2_load:
@@ -121,9 +116,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_highbits32_c2_load:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movl $-1, %eax
+; X64-TRANSFORM-NEXT:    shlxl %esi, (%rdi), %eax
 ; X64-TRANSFORM-NEXT:    shrxl %esi, %eax, %eax
-; X64-TRANSFORM-NEXT:    andl (%rdi), %eax
 ; X64-TRANSFORM-NEXT:    retq
   %val = load i32, i32* %w
   %mask = lshr i32 -1, %numhighbits
@@ -143,11 +137,10 @@
 ;
 ; X86-TRANSFORM-LABEL: clear_highbits32_c3_load_indexzext:
 ; X86-TRANSFORM:       # %bb.0:
-; X86-TRANSFORM-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-TRANSFORM-NEXT:    movl $-1, %edx
-; X86-TRANSFORM-NEXT:    shrxl %eax, %edx, %eax
-; X86-TRANSFORM-NEXT:    andl (%ecx), %eax
+; X86-TRANSFORM-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %cl
+; X86-TRANSFORM-NEXT:    shlxl %ecx, (%eax), %eax
+; X86-TRANSFORM-NEXT:    shrxl %ecx, %eax, %eax
 ; X86-TRANSFORM-NEXT:    retl
 ;
 ; X64-NOTRANSFORM-LABEL: clear_highbits32_c3_load_indexzext:
@@ -160,9 +153,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_highbits32_c3_load_indexzext:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movl $-1, %eax
+; X64-TRANSFORM-NEXT:    shlxl %esi, (%rdi), %eax
 ; X64-TRANSFORM-NEXT:    shrxl %esi, %eax, %eax
-; X64-TRANSFORM-NEXT:    andl (%rdi), %eax
 ; X64-TRANSFORM-NEXT:    retq
   %val = load i32, i32* %w
   %sh_prom = zext i8 %numhighbits to i32
@@ -183,9 +175,8 @@
 ; X86-TRANSFORM-LABEL: clear_highbits32_c4_commutative:
 ; X86-TRANSFORM:       # %bb.0:
 ; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-TRANSFORM-NEXT:    movl $-1, %ecx
+; X86-TRANSFORM-NEXT:    shlxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-TRANSFORM-NEXT:    shrxl %eax, %ecx, %eax
-; X86-TRANSFORM-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-TRANSFORM-NEXT:    retl
 ;
 ; X64-NOTRANSFORM-LABEL: clear_highbits32_c4_commutative:
@@ -198,9 +189,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_highbits32_c4_commutative:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movl $-1, %eax
+; X64-TRANSFORM-NEXT:    shlxl %esi, %edi, %eax
 ; X64-TRANSFORM-NEXT:    shrxl %esi, %eax, %eax
-; X64-TRANSFORM-NEXT:    andl %edi, %eax
 ; X64-TRANSFORM-NEXT:    retq
   %mask = lshr i32 -1, %numhighbits
   %masked = and i32 %val, %mask ; swapped order
@@ -253,9 +243,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_highbits64_c0:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movq $-1, %rax
+; X64-TRANSFORM-NEXT:    shlxq %rsi, %rdi, %rax
 ; X64-TRANSFORM-NEXT:    shrxq %rsi, %rax, %rax
-; X64-TRANSFORM-NEXT:    andq %rdi, %rax
 ; X64-TRANSFORM-NEXT:    retq
   %mask = lshr i64 -1, %numhighbits
   %masked = and i64 %mask, %val
@@ -307,9 +296,8 @@
 ; X64-TRANSFORM-LABEL: clear_highbits64_c1_indexzext:
 ; X64-TRANSFORM:       # %bb.0:
 ; X64-TRANSFORM-NEXT:    # kill: def $esi killed $esi def $rsi
-; X64-TRANSFORM-NEXT:    movq $-1, %rax
+; X64-TRANSFORM-NEXT:    shlxq %rsi, %rdi, %rax
 ; X64-TRANSFORM-NEXT:    shrxq %rsi, %rax, %rax
-; X64-TRANSFORM-NEXT:    andq %rdi, %rax
 ; X64-TRANSFORM-NEXT:    retq
   %sh_prom = zext i8 %numhighbits to i64
   %mask = lshr i64 -1, %sh_prom
@@ -367,9 +355,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_highbits64_c2_load:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movq $-1, %rax
+; X64-TRANSFORM-NEXT:    shlxq %rsi, (%rdi), %rax
 ; X64-TRANSFORM-NEXT:    shrxq %rsi, %rax, %rax
-; X64-TRANSFORM-NEXT:    andq (%rdi), %rax
 ; X64-TRANSFORM-NEXT:    retq
   %val = load i64, i64* %w
   %mask = lshr i64 -1, %numhighbits
@@ -428,9 +415,8 @@
 ; X64-TRANSFORM-LABEL: clear_highbits64_c3_load_indexzext:
 ; X64-TRANSFORM:       # %bb.0:
 ; X64-TRANSFORM-NEXT:    # kill: def $esi killed $esi def $rsi
-; X64-TRANSFORM-NEXT:    movq $-1, %rax
+; X64-TRANSFORM-NEXT:    shlxq %rsi, (%rdi), %rax
 ; X64-TRANSFORM-NEXT:    shrxq %rsi, %rax, %rax
-; X64-TRANSFORM-NEXT:    andq (%rdi), %rax
 ; X64-TRANSFORM-NEXT:    retq
   %val = load i64, i64* %w
   %sh_prom = zext i8 %numhighbits to i64
@@ -483,9 +469,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_highbits64_c4_commutative:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movq $-1, %rax
+; X64-TRANSFORM-NEXT:    shlxq %rsi, %rdi, %rax
 ; X64-TRANSFORM-NEXT:    shrxq %rsi, %rax, %rax
-; X64-TRANSFORM-NEXT:    andq %rdi, %rax
 ; X64-TRANSFORM-NEXT:    retq
   %mask = lshr i64 -1, %numhighbits
   %masked = and i64 %val, %mask ; swapped order
Index: test/CodeGen/X86/clear-lowbits.ll
===================================================================
--- test/CodeGen/X86/clear-lowbits.ll
+++ test/CodeGen/X86/clear-lowbits.ll
@@ -31,9 +31,8 @@
 ; X86-TRANSFORM-LABEL: clear_lowbits32_c0:
 ; X86-TRANSFORM:       # %bb.0:
 ; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-TRANSFORM-NEXT:    movl $-1, %ecx
+; X86-TRANSFORM-NEXT:    shrxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-TRANSFORM-NEXT:    shlxl %eax, %ecx, %eax
-; X86-TRANSFORM-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-TRANSFORM-NEXT:    retl
 ;
 ; X64-NOTRANSFORM-LABEL: clear_lowbits32_c0:
@@ -46,9 +45,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_lowbits32_c0:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movl $-1, %eax
+; X64-TRANSFORM-NEXT:    shrxl %esi, %edi, %eax
 ; X64-TRANSFORM-NEXT:    shlxl %esi, %eax, %eax
-; X64-TRANSFORM-NEXT:    andl %edi, %eax
 ; X64-TRANSFORM-NEXT:    retq
   %mask = shl i32 -1, %numlowbits
   %masked = and i32 %mask, %val
@@ -67,9 +65,8 @@
 ; X86-TRANSFORM-LABEL: clear_lowbits32_c1_indexzext:
 ; X86-TRANSFORM:       # %bb.0:
 ; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-TRANSFORM-NEXT:    movl $-1, %ecx
+; X86-TRANSFORM-NEXT:    shrxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-TRANSFORM-NEXT:    shlxl %eax, %ecx, %eax
-; X86-TRANSFORM-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-TRANSFORM-NEXT:    retl
 ;
 ; X64-NOTRANSFORM-LABEL: clear_lowbits32_c1_indexzext:
@@ -82,9 +79,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_lowbits32_c1_indexzext:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movl $-1, %eax
+; X64-TRANSFORM-NEXT:    shrxl %esi, %edi, %eax
 ; X64-TRANSFORM-NEXT:    shlxl %esi, %eax, %eax
-; X64-TRANSFORM-NEXT:    andl %edi, %eax
 ; X64-TRANSFORM-NEXT:    retq
   %sh_prom = zext i8 %numlowbits to i32
   %mask = shl i32 -1, %sh_prom
@@ -104,11 +100,10 @@
 ;
 ; X86-TRANSFORM-LABEL: clear_lowbits32_c2_load:
 ; X86-TRANSFORM:       # %bb.0:
-; X86-TRANSFORM-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-TRANSFORM-NEXT:    movl $-1, %edx
-; X86-TRANSFORM-NEXT:    shlxl %eax, %edx, %eax
-; X86-TRANSFORM-NEXT:    andl (%ecx), %eax
+; X86-TRANSFORM-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %cl
+; X86-TRANSFORM-NEXT:    shrxl %ecx, (%eax), %eax
+; X86-TRANSFORM-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-TRANSFORM-NEXT:    retl
 ;
 ; X64-NOTRANSFORM-LABEL: clear_lowbits32_c2_load:
@@ -121,9 +116,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_lowbits32_c2_load:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movl $-1, %eax
+; X64-TRANSFORM-NEXT:    shrxl %esi, (%rdi), %eax
 ; X64-TRANSFORM-NEXT:    shlxl %esi, %eax, %eax
-; X64-TRANSFORM-NEXT:    andl (%rdi), %eax
 ; X64-TRANSFORM-NEXT:    retq
   %val = load i32, i32* %w
   %mask = shl i32 -1, %numlowbits
@@ -143,11 +137,10 @@
 ;
 ; X86-TRANSFORM-LABEL: clear_lowbits32_c3_load_indexzext:
 ; X86-TRANSFORM:       # %bb.0:
-; X86-TRANSFORM-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-TRANSFORM-NEXT:    movl $-1, %edx
-; X86-TRANSFORM-NEXT:    shlxl %eax, %edx, %eax
-; X86-TRANSFORM-NEXT:    andl (%ecx), %eax
+; X86-TRANSFORM-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %cl
+; X86-TRANSFORM-NEXT:    shrxl %ecx, (%eax), %eax
+; X86-TRANSFORM-NEXT:    shlxl %ecx, %eax, %eax
 ; X86-TRANSFORM-NEXT:    retl
 ;
 ; X64-NOTRANSFORM-LABEL: clear_lowbits32_c3_load_indexzext:
@@ -160,9 +153,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_lowbits32_c3_load_indexzext:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movl $-1, %eax
+; X64-TRANSFORM-NEXT:    shrxl %esi, (%rdi), %eax
 ; X64-TRANSFORM-NEXT:    shlxl %esi, %eax, %eax
-; X64-TRANSFORM-NEXT:    andl (%rdi), %eax
 ; X64-TRANSFORM-NEXT:    retq
   %val = load i32, i32* %w
   %sh_prom = zext i8 %numlowbits to i32
@@ -183,9 +175,8 @@
 ; X86-TRANSFORM-LABEL: clear_lowbits32_c4_commutative:
 ; X86-TRANSFORM:       # %bb.0:
 ; X86-TRANSFORM-NEXT:    movb {{[0-9]+}}(%esp), %al
-; X86-TRANSFORM-NEXT:    movl $-1, %ecx
+; X86-TRANSFORM-NEXT:    shrxl %eax, {{[0-9]+}}(%esp), %ecx
 ; X86-TRANSFORM-NEXT:    shlxl %eax, %ecx, %eax
-; X86-TRANSFORM-NEXT:    andl {{[0-9]+}}(%esp), %eax
 ; X86-TRANSFORM-NEXT:    retl
 ;
 ; X64-NOTRANSFORM-LABEL: clear_lowbits32_c4_commutative:
@@ -198,9 +189,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_lowbits32_c4_commutative:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movl $-1, %eax
+; X64-TRANSFORM-NEXT:    shrxl %esi, %edi, %eax
 ; X64-TRANSFORM-NEXT:    shlxl %esi, %eax, %eax
-; X64-TRANSFORM-NEXT:    andl %edi, %eax
 ; X64-TRANSFORM-NEXT:    retq
   %mask = shl i32 -1, %numlowbits
   %masked = and i32 %val, %mask ; swapped order
@@ -253,9 +243,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_lowbits64_c0:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movq $-1, %rax
+; X64-TRANSFORM-NEXT:    shrxq %rsi, %rdi, %rax
 ; X64-TRANSFORM-NEXT:    shlxq %rsi, %rax, %rax
-; X64-TRANSFORM-NEXT:    andq %rdi, %rax
 ; X64-TRANSFORM-NEXT:    retq
   %mask = shl i64 -1, %numlowbits
   %masked = and i64 %mask, %val
@@ -307,9 +296,8 @@
 ; X64-TRANSFORM-LABEL: clear_lowbits64_c1_indexzext:
 ; X64-TRANSFORM:       # %bb.0:
 ; X64-TRANSFORM-NEXT:    # kill: def $esi killed $esi def $rsi
-; X64-TRANSFORM-NEXT:    movq $-1, %rax
+; X64-TRANSFORM-NEXT:    shrxq %rsi, %rdi, %rax
 ; X64-TRANSFORM-NEXT:    shlxq %rsi, %rax, %rax
-; X64-TRANSFORM-NEXT:    andq %rdi, %rax
 ; X64-TRANSFORM-NEXT:    retq
   %sh_prom = zext i8 %numlowbits to i64
   %mask = shl i64 -1, %sh_prom
@@ -367,9 +355,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_lowbits64_c2_load:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movq $-1, %rax
+; X64-TRANSFORM-NEXT:    shrxq %rsi, (%rdi), %rax
 ; X64-TRANSFORM-NEXT:    shlxq %rsi, %rax, %rax
-; X64-TRANSFORM-NEXT:    andq (%rdi), %rax
 ; X64-TRANSFORM-NEXT:    retq
   %val = load i64, i64* %w
   %mask = shl i64 -1, %numlowbits
@@ -428,9 +415,8 @@
 ; X64-TRANSFORM-LABEL: clear_lowbits64_c3_load_indexzext:
 ; X64-TRANSFORM:       # %bb.0:
 ; X64-TRANSFORM-NEXT:    # kill: def $esi killed $esi def $rsi
-; X64-TRANSFORM-NEXT:    movq $-1, %rax
+; X64-TRANSFORM-NEXT:    shrxq %rsi, (%rdi), %rax
 ; X64-TRANSFORM-NEXT:    shlxq %rsi, %rax, %rax
-; X64-TRANSFORM-NEXT:    andq (%rdi), %rax
 ; X64-TRANSFORM-NEXT:    retq
   %val = load i64, i64* %w
   %sh_prom = zext i8 %numlowbits to i64
@@ -483,9 +469,8 @@
 ;
 ; X64-TRANSFORM-LABEL: clear_lowbits64_c4_commutative:
 ; X64-TRANSFORM:       # %bb.0:
-; X64-TRANSFORM-NEXT:    movq $-1, %rax
+; X64-TRANSFORM-NEXT:    shrxq %rsi, %rdi, %rax
 ; X64-TRANSFORM-NEXT:    shlxq %rsi, %rax, %rax
-; X64-TRANSFORM-NEXT:    andq %rdi, %rax
 ; X64-TRANSFORM-NEXT:    retq
   %mask = shl i64 -1, %numlowbits
   %masked = and i64 %val, %mask ; swapped order