Index: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2899,12 +2899,71 @@
                                                    BinaryOperator *Add,
                                                    const APInt &C) {
   Value *Y = Add->getOperand(1);
+  Value *X = Add->getOperand(0);
+
+  Value *Op0 = X, *Op1 = Y;
+
+  // We handle all (s/zext i1 Op0 + s/zext i1 Op1 == 0/1/2) here.
+  if (Cmp.isEquality() &&
+      match(Add, m_c_Add(m_OneUse(m_ZExtOrSExt(m_Value(Op0))),
+                         m_OneUse(m_ZExtOrSExt(m_Value(Op1))))) &&
+      Op0->getType()->isIntOrIntVectorTy(1) &&
+      Op1->getType()->isIntOrIntVectorTy(1) &&
+      (C.isZero() || C.isOne() || (C.exactLogBase2() == 1))) {
+    Value *Cond = Builder.getFalse();
+    // Handle zext/zext additions
+    if (match(X, m_OneUse(m_ZExt(m_Value(Op0)))) &&
+        match(Y, m_OneUse(m_ZExt(m_Value(Op1))))) {
+      // Case 1: zext i1 Op0 + zext i1 Op1 == 0 --> !(or i1 Op0, Op1)
+      if (C.isZero())
+        Cond = Builder.CreateNot(Builder.CreateOr(Op0, Op1));
+      else if (C.isOne())
+        // Case 2:  zext i1 Op0 + zext i1 Op1 == 1 --> xor i1 Op0, Op1
+        Cond = Builder.CreateXor(Op0, Op1);
+      else if (C.exactLogBase2() == 1)
+        // Case 3: zext i1 Op0 + zext i1 Op1 == 2 --> xor i1 Op0, Op1
+        Cond = Builder.CreateAnd(Op0, Op1);
+      return replaceInstUsesWith(Cmp, Cond);
+    }
+
+    // Handles sext i1 Op0 + sext i1 Op1 == 0/1/2
+    if (match(X, m_OneUse(m_SExt(m_Value(Op0)))) &&
+        match(Y, m_OneUse(m_SExt(m_Value(Op1))))) {
+      // Case 1: sext i1 Op0 + sext i1 Op1 == 0 --> !(or i1 Op0, Op1)
+      if (C.isZero())
+        Cond = Builder.CreateNot(Builder.CreateOr(Op0, Op1));
+      // Case 2: sext i1 Op0 + sext i1 Op1 == 1 --> false
+      // Case 3: sext i1 Op0 + sext i1 Op2 == 2 --> false,
+      // these two cases were handled int initialization of Cond.
+      return replaceInstUsesWith(Cmp, Cond);
+    }
+
+    // Sum is cummulative so swap the operations to avoid recompuations
+    if (match(X, m_OneUse(m_ZExt(m_OneUse(m_Value(Op0))))) &&
+        match(Y, m_OneUse(m_SExt(m_OneUse(m_Value(Op1))))))
+      std::swap(Op0, Op1);
+
+    // Handles sext i1 Op0 + zext Op1 == 0/1/2
+    if (match(X, m_OneUse(m_SExt(m_Value(Op0)))) &&
+        match(Y, m_OneUse(m_ZExt(m_Value(Op1))))) {
+      // Case 1: sext i1 Op0 + zext i1 Op1 == 0 --> !(xor i1 Op0, Op1)
+      if (C.isZero())
+        Cond = Builder.CreateNot(Builder.CreateXor(Op0, Op1));
+      else if (C.isOne())
+        // Case 2: sext i1 Op0 + zext i1 Op1 == 1 --> (!Op0) & Op1
+        Cond = Builder.CreateAnd(Builder.CreateNot(Op0), Op1);
+      // Case 3: sext i1 Op0 + zext i1 Op1 == 2 --> false,
+      // already handled in the initilization of Cond.
+      return replaceInstUsesWith(Cmp, Cond);
+    }
+    return nullptr;
+  }
+
   const APInt *C2;
-  if (Cmp.isEquality() || !match(Y, m_APInt(C2)))
+  if (!match(Y, m_APInt(C2)))
     return nullptr;
 
   // Fold icmp pred (add X, C2), C.
-  Value *X = Add->getOperand(0);
   Type *Ty = Add->getType();
   const CmpInst::Predicate Pred = Cmp.getPredicate();
 
Index: llvm/test/Transforms/InstCombine/icmp-add.ll
===================================================================
--- llvm/test/Transforms/InstCombine/icmp-add.ll
+++ llvm/test/Transforms/InstCombine/icmp-add.ll
@@ -5,6 +5,133 @@
 
 ; PR1949
 
+define i1 @cvt_icmp_0_zext_plus_zext(i1 %arg, i1 %arg1) {
+; CHECK-LABEL: @cvt_icmp_0_zext_plus_zext(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    [[TMP0:%.*]] = or i1 [[ARG1:%.*]], [[ARG:%.*]]
+; CHECK-NEXT:    [[I4:%.*]] = xor i1 [[TMP0]], true
+; CHECK-NEXT:    ret i1 [[I4]]
+;
+bb:
+  %i = zext i1 %arg to i32
+  %i2 = zext i1 %arg1 to i32
+  %i3 = add i32 %i2, %i
+  %i4 = icmp eq i32 %i3, 0
+  ret i1 %i4
+}
+
+define i1 @cvt_icmp_1_zext_plus_zext(i1 %arg, i1 %arg1) {
+; CHECK-LABEL: @cvt_icmp_1_zext_plus_zext(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    [[I4:%.*]] = xor i1 [[ARG1:%.*]], [[ARG:%.*]]
+; CHECK-NEXT:    ret i1 [[I4]]
+;
+bb:
+  %i = zext i1 %arg to i32
+  %i2 = zext i1 %arg1 to i32
+  %i3 = add i32 %i2, %i
+  %i4 = icmp eq i32 %i3, 1
+  ret i1 %i4
+}
+
+define i1 @cvt_icmp_2_zext_plus_zext(i1 %arg, i1 %arg1) {
+; CHECK-LABEL: @cvt_icmp_2_zext_plus_zext(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    [[T:%.*]] = and i1 [[ARG:%.*]], [[ARG1:%.*]]
+; CHECK-NEXT:    ret i1 [[T]]
+;
+bb:
+  %i = zext i1 %arg to i32
+  %i2 = zext i1 %arg1 to i32
+  %i3 = add i32 %i, %i2
+  %t = icmp eq i32 %i3, 2
+  ret i1 %t
+}
+
+define i1 @cvt_icmp_0_sext_plus_sext(i1 %arg, i1 %arg1) {
+; CHECK-LABEL: @cvt_icmp_0_sext_plus_sext(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    [[TMP0:%.*]] = or i1 [[ARG:%.*]], [[ARG1:%.*]]
+; CHECK-NEXT:    [[T:%.*]] = xor i1 [[TMP0]], true
+; CHECK-NEXT:    ret i1 [[T]]
+;
+bb:
+  %i = sext i1 %arg to i32
+  %i2 = sext i1 %arg1 to i32
+  %i3 = add i32 %i, %i2
+  %t = icmp eq i32 %i3, 0
+  ret i1 %t
+}
+
+define i1 @cvt_icmp_1_sext_plus_sext(i1 %arg, i1 %arg1) {
+; CHECK-LABEL: @cvt_icmp_1_sext_plus_sext(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    ret i1 false
+;
+bb:
+  %i = sext i1 %arg to i32
+  %i2 = sext i1 %arg1 to i32
+  %i3 = add i32 %i, %i2
+  %t = icmp eq i32 %i3, 1
+  ret i1 %t
+}
+
+define i1 @cvt_icmp_2_sext_plus_sext(i1 %arg, i1 %arg1) {
+; CHECK-LABEL: @cvt_icmp_2_sext_plus_sext(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    ret i1 false
+;
+bb:
+  %i = sext i1 %arg to i32
+  %i2 = sext i1 %arg1 to i32
+  %i3 = add i32 %i, %i2
+  %t = icmp eq i32 %i3, 2
+  ret i1 %t
+}
+
+define i1 @cvt_icmp_0_sext_plus_zext(i1 %arg, i1 %arg1) {
+; CHECK-LABEL: @cvt_icmp_0_sext_plus_zext(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    [[TMP0:%.*]] = xor i1 [[ARG:%.*]], [[ARG1:%.*]]
+; CHECK-NEXT:    [[T:%.*]] = xor i1 [[TMP0]], true
+; CHECK-NEXT:    ret i1 [[T]]
+;
+bb:
+  %i = sext i1 %arg to i32
+  %i2 = zext i1 %arg1 to i32
+  %i3 = add i32 %i, %i2
+  %t = icmp eq i32 %i3, 0
+  ret i1 %t
+}
+
+define i1 @cvt_icmp_1_sext_plus_zext(i1 %arg, i1 %arg1) {
+; CHECK-LABEL: @cvt_icmp_1_sext_plus_zext(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    [[TMP0:%.*]] = xor i1 [[ARG:%.*]], true
+; CHECK-NEXT:    [[T:%.*]] = and i1 [[TMP0]], [[ARG1:%.*]]
+; CHECK-NEXT:    ret i1 [[T]]
+;
+bb:
+  %i = sext i1 %arg to i32
+  %i2 = zext i1 %arg1 to i32
+  %i3 = add i32 %i, %i2
+  %t = icmp eq i32 %i3, 1
+  ret i1 %t
+}
+
+define i1 @cvt_icmp_2_sext_plus_zext(i1 %arg, i1 %arg1) {
+; CHECK-LABEL: @cvt_icmp_2_sext_plus_zext(
+; CHECK-NEXT:  bb:
+; CHECK-NEXT:    ret i1 false
+;
+bb:
+  %i = sext i1 %arg to i32
+  %i2 = zext i1 %arg1 to i32
+  %i3 = add i32 %i, %i2
+  %t = icmp eq i32 %i3, 2
+  ret i1 %t
+}
+
 define i1 @test1(i32 %a) {
 ; CHECK-LABEL: @test1(
 ; CHECK-NEXT:    [[C:%.*]] = icmp ugt i32 [[A:%.*]], -5