diff --git a/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp b/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
--- a/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -3854,14 +3854,29 @@
       // If we are shifting by N-X where N == 0 mod Size, then just shift by -X
       // to generate a NEG instead of a SUB of a constant.
     } else if (ShiftAmt->getOpcode() == ISD::SUB && Add0C &&
-               Add0C->getAPIntValue() != 0 &&
-               Add0C->getAPIntValue().urem(Size) == 0) {
+               Add0C->getZExtValue() != 0) {
+      EVT SubVT = ShiftAmt.getValueType();
+      SDValue X;
+      if (Add0C->getZExtValue() % Size == 0)
+        X = Add1;
+      else if (ShiftAmt.hasOneUse() && Size == 64 &&
+               Add0C->getZExtValue() % 32 == 0) {
+        // We have a 64-bit shift by (n*32-x), turn it into -(x+n*32).
+        // This is mainly beneficial if we already compute (x+n*32).
+        if (Add1.getOpcode() == ISD::TRUNCATE) {
+          Add1 = Add1.getOperand(0);
+          SubVT = Add1.getValueType();
+        }
+        X = CurDAG->getNode(ISD::ADD, DL, SubVT, Add1,
+                            CurDAG->getZExtOrTrunc(Add0, DL, SubVT));
+        insertDAGNode(*CurDAG, OrigShiftAmt, X);
+      } else
+        return false;
       // Insert a negate op.
       // TODO: This isn't guaranteed to replace the sub if there is a logic cone
       // that uses it that's not a shift.
-      EVT SubVT = ShiftAmt.getValueType();
       SDValue Zero = CurDAG->getConstant(0, DL, SubVT);
-      SDValue Neg = CurDAG->getNode(ISD::SUB, DL, SubVT, Zero, Add1);
+      SDValue Neg = CurDAG->getNode(ISD::SUB, DL, SubVT, Zero, X);
       NewShiftAmt = Neg;
 
       // Insert these operands into a valid topological order so they can
diff --git a/llvm/test/CodeGen/X86/64-bit-shift-by-32-minus-y.ll b/llvm/test/CodeGen/X86/64-bit-shift-by-32-minus-y.ll
--- a/llvm/test/CodeGen/X86/64-bit-shift-by-32-minus-y.ll
+++ b/llvm/test/CodeGen/X86/64-bit-shift-by-32-minus-y.ll
@@ -8,16 +8,17 @@
 ; X64-NOBMI2-LABEL: t0:
 ; X64-NOBMI2:       # %bb.0:
 ; X64-NOBMI2-NEXT:    movq %rdi, %rax
-; X64-NOBMI2-NEXT:    movb $32, %cl
-; X64-NOBMI2-NEXT:    subb %sil, %cl
+; X64-NOBMI2-NEXT:    leaq 32(%rsi), %rcx
+; X64-NOBMI2-NEXT:    negq %rcx
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; X64-NOBMI2-NEXT:    shlq %cl, %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: t0:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movb $32, %al
-; X64-BMI2-NEXT:    subb %sil, %al
-; X64-BMI2-NEXT:    shlxq %rax, %rdi, %rax
+; X64-BMI2-NEXT:    addq $32, %rsi
+; X64-BMI2-NEXT:    negq %rsi
+; X64-BMI2-NEXT:    shlxq %rsi, %rdi, %rax
 ; X64-BMI2-NEXT:    retq
 ;
 ; X32-NOBMI2-LABEL: t0:
@@ -228,16 +229,17 @@
 ; X64-NOBMI2-LABEL: t4:
 ; X64-NOBMI2:       # %bb.0:
 ; X64-NOBMI2-NEXT:    movq %rdi, %rax
-; X64-NOBMI2-NEXT:    movb $96, %cl
-; X64-NOBMI2-NEXT:    subb %sil, %cl
+; X64-NOBMI2-NEXT:    leaq 96(%rsi), %rcx
+; X64-NOBMI2-NEXT:    negq %rcx
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; X64-NOBMI2-NEXT:    shlq %cl, %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: t4:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    movb $96, %al
-; X64-BMI2-NEXT:    subb %sil, %al
-; X64-BMI2-NEXT:    shlxq %rax, %rdi, %rax
+; X64-BMI2-NEXT:    addq $96, %rsi
+; X64-BMI2-NEXT:    negq %rsi
+; X64-BMI2-NEXT:    shlxq %rsi, %rdi, %rax
 ; X64-BMI2-NEXT:    retq
 ;
 ; X32-NOBMI2-LABEL: t4:
@@ -282,21 +284,21 @@
 define i64 @t5_cse(i64 %val, i64 %shamt, i64*%dst) nounwind {
 ; X64-NOBMI2-LABEL: t5_cse:
 ; X64-NOBMI2:       # %bb.0:
+; X64-NOBMI2-NEXT:    movq %rsi, %rcx
 ; X64-NOBMI2-NEXT:    movq %rdi, %rax
-; X64-NOBMI2-NEXT:    leaq 32(%rsi), %rcx
+; X64-NOBMI2-NEXT:    addq $32, %rcx
 ; X64-NOBMI2-NEXT:    movq %rcx, (%rdx)
-; X64-NOBMI2-NEXT:    movb $32, %cl
-; X64-NOBMI2-NEXT:    subb %sil, %cl
+; X64-NOBMI2-NEXT:    negq %rcx
+; X64-NOBMI2-NEXT:    # kill: def $cl killed $cl killed $rcx
 ; X64-NOBMI2-NEXT:    shlq %cl, %rax
 ; X64-NOBMI2-NEXT:    retq
 ;
 ; X64-BMI2-LABEL: t5_cse:
 ; X64-BMI2:       # %bb.0:
-; X64-BMI2-NEXT:    leaq 32(%rsi), %rax
-; X64-BMI2-NEXT:    movq %rax, (%rdx)
-; X64-BMI2-NEXT:    movb $32, %al
-; X64-BMI2-NEXT:    subb %sil, %al
-; X64-BMI2-NEXT:    shlxq %rax, %rdi, %rax
+; X64-BMI2-NEXT:    addq $32, %rsi
+; X64-BMI2-NEXT:    movq %rsi, (%rdx)
+; X64-BMI2-NEXT:    negq %rsi
+; X64-BMI2-NEXT:    shlxq %rsi, %rdi, %rax
 ; X64-BMI2-NEXT:    retq
 ;
 ; X32-NOBMI2-LABEL: t5_cse: