Index: llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
===================================================================
--- llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -369,6 +369,12 @@
             (isOneConstant(SDValue(N, 0)) || isAllOnesConstant(SDValue(N, 0))))
           continue;
 
+        // If this is a sign-extended 8-bit integer immediate used in an ALU
+        // instruction, there is probably an opcode encoding to save space.
+        auto *C = dyn_cast<ConstantSDNode>(N);
+        if (C && isInt<8>(C->getSExtValue()))
+          continue;
+
         // Immediates that are used for offsets as part of stack
         // manipulation should be left alone. These are typically
         // used to indicate SP offsets for argument passing and
Index: llvm/test/CodeGen/X86/immediate_merging.ll
===================================================================
--- llvm/test/CodeGen/X86/immediate_merging.ll
+++ llvm/test/CodeGen/X86/immediate_merging.ll
@@ -19,9 +19,8 @@
 ; X86-NEXT:    movl $1234, %eax # imm = 0x4D2
 ; X86-NEXT:    movl %eax, a
 ; X86-NEXT:    movl %eax, b
-; X86-NEXT:    movl $12, %eax
-; X86-NEXT:    movl %eax, c
-; X86-NEXT:    cmpl %eax, e
+; X86-NEXT:    movl $12, c
+; X86-NEXT:    cmpl $12, e
 ; X86-NEXT:    jne .LBB0_2
 ; X86-NEXT:  # %bb.1: # %if.then
 ; X86-NEXT:    movl $1, x
@@ -38,9 +37,8 @@
 ; X64-NEXT:    movl $1234, %eax # imm = 0x4D2
 ; X64-NEXT:    movl %eax, {{.*}}(%rip)
 ; X64-NEXT:    movl %eax, {{.*}}(%rip)
-; X64-NEXT:    movl $12, %eax
-; X64-NEXT:    movl %eax, {{.*}}(%rip)
-; X64-NEXT:    cmpl %eax, {{.*}}(%rip)
+; X64-NEXT:    movl $12, {{.*}}(%rip)
+; X64-NEXT:    cmpl $12, {{.*}}(%rip)
 ; X64-NEXT:    jne .LBB0_2
 ; X64-NEXT:  # %bb.1: # %if.then
 ; X64-NEXT:    movl $1, {{.*}}(%rip)
@@ -81,9 +79,8 @@
 ; X86-NEXT:    movl $1234, %eax # imm = 0x4D2
 ; X86-NEXT:    movl %eax, a
 ; X86-NEXT:    movl %eax, b
-; X86-NEXT:    movl $12, %eax
-; X86-NEXT:    movl %eax, c
-; X86-NEXT:    cmpl %eax, e
+; X86-NEXT:    movl $12, c
+; X86-NEXT:    cmpl $12, e
 ; X86-NEXT:    jne .LBB1_2
 ; X86-NEXT:  # %bb.1: # %if.then
 ; X86-NEXT:    movl $1, x
@@ -100,9 +97,8 @@
 ; X64-NEXT:    movl $1234, %eax # imm = 0x4D2
 ; X64-NEXT:    movl %eax, {{.*}}(%rip)
 ; X64-NEXT:    movl %eax, {{.*}}(%rip)
-; X64-NEXT:    movl $12, %eax
-; X64-NEXT:    movl %eax, {{.*}}(%rip)
-; X64-NEXT:    cmpl %eax, {{.*}}(%rip)
+; X64-NEXT:    movl $12, {{.*}}(%rip)
+; X64-NEXT:    cmpl $12, {{.*}}(%rip)
 ; X64-NEXT:    jne .LBB1_2
 ; X64-NEXT:  # %bb.1: # %if.then
 ; X64-NEXT:    movl $1, {{.*}}(%rip)
Index: llvm/test/CodeGen/X86/immediate_merging64.ll
===================================================================
--- llvm/test/CodeGen/X86/immediate_merging64.ll
+++ llvm/test/CodeGen/X86/immediate_merging64.ll
@@ -9,9 +9,8 @@
 define i1 @imm_multiple_users(i64 %a, i64* %b) optsize {
 ; CHECK-LABEL: imm_multiple_users:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    movq $-1, %rax
-; CHECK-NEXT:    movq %rax, (%rsi)
-; CHECK-NEXT:    cmpq %rax, %rdi
+; CHECK-NEXT:    movq $-1, (%rsi)
+; CHECK-NEXT:    cmpq $-1, %rdi
 ; CHECK-NEXT:    sete %al
 ; CHECK-NEXT:    retq
   store i64 -1, i64* %b, align 8
@@ -22,9 +21,8 @@
 define i1 @imm_multiple_users_pgso(i64 %a, i64* %b) !prof !14 {
 ; CHECK-LABEL: imm_multiple_users_pgso:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    movq $-1, %rax
-; CHECK-NEXT:    movq %rax, (%rsi)
-; CHECK-NEXT:    cmpq %rax, %rdi
+; CHECK-NEXT:    movq $-1, (%rsi)
+; CHECK-NEXT:    cmpq $-1, %rdi
 ; CHECK-NEXT:    sete %al
 ; CHECK-NEXT:    retq
   store i64 -1, i64* %b, align 8
Index: llvm/test/CodeGen/X86/pr27202.ll
===================================================================
--- llvm/test/CodeGen/X86/pr27202.ll
+++ llvm/test/CodeGen/X86/pr27202.ll
@@ -17,9 +17,8 @@
 define zeroext i1 @g(i32 %x) optsize {
 ; CHECK-LABEL: g:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    movl $1, %eax
-; CHECK-NEXT:    orl %eax, %edi
-; CHECK-NEXT:    cmpl %eax, %edi
+; CHECK-NEXT:    orl $1, %edi
+; CHECK-NEXT:    cmpl $1, %edi
 ; CHECK-NEXT:    sete %al
 ; CHECK-NEXT:    retq
   %t0 = or i32 %x, 1
@@ -36,9 +35,8 @@
 ; CHECK-NEXT:    movl %edx, %eax
 ; CHECK-NEXT:    shll $6, %eax
 ; CHECK-NEXT:    movzbl %al, %ecx
-; CHECK-NEXT:    movl $7, %eax
-; CHECK-NEXT:    andq %rax, %rsi
-; CHECK-NEXT:    andq %rax, %rdx
+; CHECK-NEXT:    andl $7, %esi
+; CHECK-NEXT:    andl $7, %edx
 ; CHECK-NEXT:    leaq (%rdx,%rsi,8), %rax
 ; CHECK-NEXT:    orq %rcx, %rax
 ; CHECK-NEXT:    retq