diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2186,13 +2186,14 @@
       }
     }
 
-    // Undo the add -> or combine to merge constant offsets from a frame index.
+    // Fold (add (or x, c0), c1) -> (add x, (c0 + c1)) if (or x, c0) is
+    // equivalent to (add x, c0).
     if (N0.getOpcode() == ISD::OR &&
-        isa<FrameIndexSDNode>(N0.getOperand(0)) &&
-        isa<ConstantSDNode>(N0.getOperand(1)) &&
+        isConstantOrConstantVector(N0.getOperand(1), /* NoOpaque */ true) &&
         DAG.haveNoCommonBitsSet(N0.getOperand(0), N0.getOperand(1))) {
-      SDValue Add0 = DAG.getNode(ISD::ADD, DL, VT, N1, N0.getOperand(1));
-      return DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(0), Add0);
+      if (SDValue Add0 = DAG.FoldConstantArithmetic(ISD::ADD, DL, VT,
+                                                    {N1, N0.getOperand(1)}))
+        return DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(0), Add0);
     }
   }
 
diff --git a/llvm/test/CodeGen/ARM/va_arg.ll b/llvm/test/CodeGen/ARM/va_arg.ll
--- a/llvm/test/CodeGen/ARM/va_arg.ll
+++ b/llvm/test/CodeGen/ARM/va_arg.ll
@@ -13,10 +13,10 @@
 ; CHECK-NEXT:    stmib sp, {r1, r2, r3}
 ; CHECK-NEXT:    add r0, r0, #7
 ; CHECK-NEXT:    bic r1, r0, #7
-; CHECK-NEXT:    orr r2, r1, #4
-; CHECK-NEXT:    str r2, [sp]
+; CHECK-NEXT:    orr r0, r1, #4
+; CHECK-NEXT:    str r0, [sp]
 ; CHECK-NEXT:    ldr r0, [r1]
-; CHECK-NEXT:    add r2, r2, #4
+; CHECK-NEXT:    add r2, r1, #8
 ; CHECK-NEXT:    str r2, [sp]
 ; CHECK-NEXT:    ldr r1, [r1, #4]
 ; CHECK-NEXT:    add sp, sp, #4
diff --git a/llvm/test/CodeGen/Mips/cconv/arguments-varargs.ll b/llvm/test/CodeGen/Mips/cconv/arguments-varargs.ll
--- a/llvm/test/CodeGen/Mips/cconv/arguments-varargs.ll
+++ b/llvm/test/CodeGen/Mips/cconv/arguments-varargs.ll
@@ -316,7 +316,7 @@
 ; O32-DAG:       addiu [[GV:\$[0-9]+]], ${{[0-9]+}}, %lo(dwords)
 ; O32-DAG:       lw [[ARG1:\$[0-9]+]], 0([[VA_TMP2]])
 ; O32-DAG:       sw [[ARG1]], 8([[GV]])
-; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA2]], 4
+; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA_TMP2]], 8
 ; O32-DAG:       sw [[VA3]], 0([[SP]])
 ; O32-DAG:       lw [[ARG1:\$[0-9]+]], 4([[VA_TMP2]])
 ; O32-DAG:       sw [[ARG1]], 12([[GV]])
@@ -347,7 +347,7 @@
 ; Load the second argument from the variable portion and copy it to the global.
 ; O32-DAG:       lw [[ARG2:\$[0-9]+]], 0([[VA]])
 ; O32-DAG:       sw [[ARG2]], 16([[GV]])
-; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA2]], 4
+; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA_TMP2]], 8
 ; O32-DAG:       sw [[VA3]], 0([[SP]])
 ; O32-DAG:       lw [[ARG2:\$[0-9]+]], 4([[VA_TMP2]])
 ; O32-DAG:       sw [[ARG2]], 20([[GV]])
@@ -668,7 +668,7 @@
 ; O32-DAG:       addiu [[GV:\$[0-9]+]], ${{[0-9]+}}, %lo(dwords)
 ; O32-DAG:       lw [[ARG1:\$[0-9]+]], 0([[VA_TMP2]])
 ; O32-DAG:       sw [[ARG1]], 8([[GV]])
-; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA2]], 4
+; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA_TMP2]], 8
 ; O32-DAG:       sw [[VA3]], 0([[SP]])
 ; O32-DAG:       lw [[ARG1:\$[0-9]+]], 4([[VA_TMP2]])
 ; O32-DAG:       sw [[ARG1]], 12([[GV]])
@@ -699,8 +699,8 @@
 ; Load the second argument from the variable portion and copy it to the global.
 ; O32-DAG:       lw [[ARG2:\$[0-9]+]], 0([[VA]])
 ; O32-DAG:       sw [[ARG2]], 16([[GV]])
-; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA2]], 4
-; O32-DAG:       sw [[VA2]], 0([[SP]])
+; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA_TMP2]], 8
+; O32-DAG:       sw [[VA3]], 0([[SP]])
 ; O32-DAG:       lw [[ARG2:\$[0-9]+]], 4([[VA_TMP2]])
 ; O32-DAG:       sw [[ARG2]], 20([[GV]])
 
@@ -1017,7 +1017,7 @@
 ; O32-DAG:       addiu [[GV:\$[0-9]+]], ${{[0-9]+}}, %lo(dwords)
 ; O32-DAG:       lw [[ARG1:\$[0-9]+]], 0([[VA]])
 ; O32-DAG:       sw [[ARG1]], 8([[GV]])
-; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA2]], 4
+; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA_TMP2]], 8
 ; O32-DAG:       sw [[VA3]], 0([[SP]])
 ; O32-DAG:       lw [[ARG1:\$[0-9]+]], 4([[VA_TMP2]])
 ; O32-DAG:       sw [[ARG1]], 12([[GV]])
@@ -1047,11 +1047,11 @@
 
 ; Load the second argument from the variable portion and copy it to the global.
 ; O32-DAG:       lw [[ARG2:\$[0-9]+]], 0([[VA]])
-; O32-DAG:       sw [[ARG2]], 16([[GV]])
-; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA2]], 4
+; O32-DAG:       addiu [[VA3:\$[0-9]+]], [[VA_TMP2]], 8
 ; O32-DAG:       sw [[VA3]], 0([[SP]])
-; O32-DAG:       lw [[ARG2:\$[0-9]+]], 4([[VA_TMP2]])
-; O32-DAG:       sw [[ARG2]], 20([[GV]])
+; O32-DAG:       lw [[ARG3:\$[0-9]+]], 4([[VA_TMP2]])
+; O32-DAG:       sw [[ARG3]], 20([[GV]])
+; O32-DAG:       sw [[ARG2]], 16([[GV]])
 
 ; NEW-DAG:       ld [[ARG2:\$[0-9]+]], 0([[VA2]])
 ; NEW-DAG:       sd [[ARG2]], 16([[GV]])
diff --git a/llvm/test/CodeGen/RISCV/vararg.ll b/llvm/test/CodeGen/RISCV/vararg.ll
--- a/llvm/test/CodeGen/RISCV/vararg.ll
+++ b/llvm/test/CodeGen/RISCV/vararg.ll
@@ -651,13 +651,13 @@
 ; ILP32-ILP32F-FPELIM-NEXT:    sw a2, 24(sp)
 ; ILP32-ILP32F-FPELIM-NEXT:    sw a1, 20(sp)
 ; ILP32-ILP32F-FPELIM-NEXT:    addi a0, sp, 27
-; ILP32-ILP32F-FPELIM-NEXT:    andi a0, a0, -8
-; ILP32-ILP32F-FPELIM-NEXT:    ori a1, a0, 4
-; ILP32-ILP32F-FPELIM-NEXT:    sw a1, 12(sp)
-; ILP32-ILP32F-FPELIM-NEXT:    lw a0, 0(a0)
-; ILP32-ILP32F-FPELIM-NEXT:    addi a2, a1, 4
+; ILP32-ILP32F-FPELIM-NEXT:    andi a1, a0, -8
+; ILP32-ILP32F-FPELIM-NEXT:    ori a2, a1, 4
 ; ILP32-ILP32F-FPELIM-NEXT:    sw a2, 12(sp)
-; ILP32-ILP32F-FPELIM-NEXT:    lw a1, 0(a1)
+; ILP32-ILP32F-FPELIM-NEXT:    lw a0, 0(a1)
+; ILP32-ILP32F-FPELIM-NEXT:    addi a1, a1, 8
+; ILP32-ILP32F-FPELIM-NEXT:    sw a1, 12(sp)
+; ILP32-ILP32F-FPELIM-NEXT:    lw a1, 0(a2)
 ; ILP32-ILP32F-FPELIM-NEXT:    addi sp, sp, 48
 ; ILP32-ILP32F-FPELIM-NEXT:    ret
 ;
@@ -675,13 +675,13 @@
 ; ILP32-ILP32F-WITHFP-NEXT:    sw a2, 8(s0)
 ; ILP32-ILP32F-WITHFP-NEXT:    sw a1, 4(s0)
 ; ILP32-ILP32F-WITHFP-NEXT:    addi a0, s0, 11
-; ILP32-ILP32F-WITHFP-NEXT:    andi a0, a0, -8
-; ILP32-ILP32F-WITHFP-NEXT:    ori a1, a0, 4
-; ILP32-ILP32F-WITHFP-NEXT:    sw a1, -12(s0)
-; ILP32-ILP32F-WITHFP-NEXT:    lw a0, 0(a0)
-; ILP32-ILP32F-WITHFP-NEXT:    addi a2, a1, 4
+; ILP32-ILP32F-WITHFP-NEXT:    andi a1, a0, -8
+; ILP32-ILP32F-WITHFP-NEXT:    ori a2, a1, 4
 ; ILP32-ILP32F-WITHFP-NEXT:    sw a2, -12(s0)
-; ILP32-ILP32F-WITHFP-NEXT:    lw a1, 0(a1)
+; ILP32-ILP32F-WITHFP-NEXT:    lw a0, 0(a1)
+; ILP32-ILP32F-WITHFP-NEXT:    addi a1, a1, 8
+; ILP32-ILP32F-WITHFP-NEXT:    sw a1, -12(s0)
+; ILP32-ILP32F-WITHFP-NEXT:    lw a1, 0(a2)
 ; ILP32-ILP32F-WITHFP-NEXT:    lw s0, 8(sp)
 ; ILP32-ILP32F-WITHFP-NEXT:    lw ra, 12(sp)
 ; ILP32-ILP32F-WITHFP-NEXT:    addi sp, sp, 48
@@ -982,11 +982,11 @@
 ; ILP32-ILP32F-FPELIM-NEXT:    andi a0, a0, -8
 ; ILP32-ILP32F-FPELIM-NEXT:    ori a3, a0, 4
 ; ILP32-ILP32F-FPELIM-NEXT:    sw a3, 4(sp)
-; ILP32-ILP32F-FPELIM-NEXT:    lw a0, 0(a0)
-; ILP32-ILP32F-FPELIM-NEXT:    addi a4, a3, 4
-; ILP32-ILP32F-FPELIM-NEXT:    sw a4, 4(sp)
+; ILP32-ILP32F-FPELIM-NEXT:    lw a4, 0(a0)
+; ILP32-ILP32F-FPELIM-NEXT:    addi a0, a0, 8
+; ILP32-ILP32F-FPELIM-NEXT:    sw a0, 4(sp)
 ; ILP32-ILP32F-FPELIM-NEXT:    lw a3, 0(a3)
-; ILP32-ILP32F-FPELIM-NEXT:    add a0, a1, a0
+; ILP32-ILP32F-FPELIM-NEXT:    add a0, a1, a4
 ; ILP32-ILP32F-FPELIM-NEXT:    sltu a1, a0, a1
 ; ILP32-ILP32F-FPELIM-NEXT:    add a2, a2, a3
 ; ILP32-ILP32F-FPELIM-NEXT:    add a1, a2, a1
@@ -1008,11 +1008,11 @@
 ; ILP32-ILP32F-WITHFP-NEXT:    andi a0, a0, -8
 ; ILP32-ILP32F-WITHFP-NEXT:    ori a3, a0, 4
 ; ILP32-ILP32F-WITHFP-NEXT:    sw a3, -12(s0)
-; ILP32-ILP32F-WITHFP-NEXT:    lw a0, 0(a0)
-; ILP32-ILP32F-WITHFP-NEXT:    addi a4, a3, 4
-; ILP32-ILP32F-WITHFP-NEXT:    sw a4, -12(s0)
+; ILP32-ILP32F-WITHFP-NEXT:    lw a4, 0(a0)
+; ILP32-ILP32F-WITHFP-NEXT:    addi a0, a0, 8
+; ILP32-ILP32F-WITHFP-NEXT:    sw a0, -12(s0)
 ; ILP32-ILP32F-WITHFP-NEXT:    lw a3, 0(a3)
-; ILP32-ILP32F-WITHFP-NEXT:    add a0, a1, a0
+; ILP32-ILP32F-WITHFP-NEXT:    add a0, a1, a4
 ; ILP32-ILP32F-WITHFP-NEXT:    sltu a1, a0, a1
 ; ILP32-ILP32F-WITHFP-NEXT:    add a2, a2, a3
 ; ILP32-ILP32F-WITHFP-NEXT:    add a1, a2, a1