diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -130,6 +130,7 @@
 EnableCodeSinking("instcombine-code-sinking", cl::desc("Enable code sinking"),
                                               cl::init(true));
 
+// FIXME: This option is no longer used for anything and may be removed.
 static cl::opt<bool>
 EnableExpensiveCombines("expensive-combines",
                         cl::desc("Enable expensive instruction combines"));
@@ -3491,27 +3492,6 @@
       }
     }
 
-    // In general, it is possible for computeKnownBits to determine all bits in
-    // a value even when the operands are not all constants.
-    Type *Ty = I->getType();
-    if (ExpensiveCombines && !I->use_empty() && Ty->isIntOrIntVectorTy() &&
-        !isMustTailCall(I)) {
-      KnownBits Known = computeKnownBits(I, /*Depth*/0, I);
-      if (Known.isConstant()) {
-        Constant *C = ConstantInt::get(Ty, Known.getConstant());
-        LLVM_DEBUG(dbgs() << "IC: ConstFold (all bits known) to: " << *C
-                          << " from: " << *I << '\n');
-
-        // Add operands to the worklist.
-        replaceInstUsesWith(*I, C);
-        ++NumConstProp;
-        if (isInstructionTriviallyDead(I, &TLI))
-          eraseInstFromFunction(*I);
-        MadeIRChange = true;
-        continue;
-      }
-    }
-
     // See if we can trivially sink this instruction to a successor basic block.
     if (EnableCodeSinking && I->hasOneUse()) {
       BasicBlock *BB = I->getParent();
diff --git a/llvm/test/Transforms/InstCombine/assume.ll b/llvm/test/Transforms/InstCombine/assume.ll
--- a/llvm/test/Transforms/InstCombine/assume.ll
+++ b/llvm/test/Transforms/InstCombine/assume.ll
@@ -353,16 +353,12 @@
 ; PR35846 - https://bugs.llvm.org/show_bug.cgi?id=35846
 
 define i32 @assumption_conflicts_with_known_bits(i32 %a, i32 %b) {
-; EXPENSIVE-ON-LABEL: @assumption_conflicts_with_known_bits(
-; EXPENSIVE-ON-NEXT:    tail call void @llvm.assume(i1 false)
-; EXPENSIVE-ON-NEXT:    ret i32 0
-;
-; EXPENSIVE-OFF-LABEL: @assumption_conflicts_with_known_bits(
-; EXPENSIVE-OFF-NEXT:    [[AND1:%.*]] = and i32 [[B:%.*]], 3
-; EXPENSIVE-OFF-NEXT:    tail call void @llvm.assume(i1 false)
-; EXPENSIVE-OFF-NEXT:    [[CMP2:%.*]] = icmp eq i32 [[AND1]], 0
-; EXPENSIVE-OFF-NEXT:    tail call void @llvm.assume(i1 [[CMP2]])
-; EXPENSIVE-OFF-NEXT:    ret i32 0
+; CHECK-LABEL: @assumption_conflicts_with_known_bits(
+; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[B:%.*]], 3
+; CHECK-NEXT:    tail call void @llvm.assume(i1 false)
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp eq i32 [[AND1]], 0
+; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP2]])
+; CHECK-NEXT:    ret i32 0
 ;
   %and1 = and i32 %b, 3
   %B1 = lshr i32 %and1, %and1
diff --git a/llvm/test/Transforms/InstCombine/known-signbit-shift.ll b/llvm/test/Transforms/InstCombine/known-signbit-shift.ll
--- a/llvm/test/Transforms/InstCombine/known-signbit-shift.ll
+++ b/llvm/test/Transforms/InstCombine/known-signbit-shift.ll
@@ -30,11 +30,8 @@
 ; If sign bit is a known zero, it cannot be a known one.
 ; This test should not crash opt. The shift produces poison.
 define i32 @test_no_sign_bit_conflict1(i1 %b) {
-; EXPENSIVE-OFF-LABEL: @test_no_sign_bit_conflict1(
-; EXPENSIVE-OFF-NEXT:    ret i32 undef
-;
-; EXPENSIVE-ON-LABEL: @test_no_sign_bit_conflict1(
-; EXPENSIVE-ON-NEXT:    ret i32 0
+; CHECK-LABEL: @test_no_sign_bit_conflict1(
+; CHECK-NEXT:    ret i32 undef
 ;
   %sel = select i1 %b, i32 8193, i32 8192
   %mul = shl nsw i32 %sel, 18
@@ -44,11 +41,8 @@
 ; If sign bit is a known one, it cannot be a known zero.
 ; This test should not crash opt. The shift produces poison.
 define i32 @test_no_sign_bit_conflict2(i1 %b) {
-; EXPENSIVE-OFF-LABEL: @test_no_sign_bit_conflict2(
-; EXPENSIVE-OFF-NEXT:    ret i32 undef
-;
-; EXPENSIVE-ON-LABEL: @test_no_sign_bit_conflict2(
-; EXPENSIVE-ON-NEXT:    ret i32 0
+; CHECK-LABEL: @test_no_sign_bit_conflict2(
+; CHECK-NEXT:    ret i32 undef
 ;
   %sel = select i1 %b, i32 -8193, i32 -8194
   %mul = shl nsw i32 %sel, 18
diff --git a/llvm/test/Transforms/InstCombine/out-of-bounds-indexes.ll b/llvm/test/Transforms/InstCombine/out-of-bounds-indexes.ll
--- a/llvm/test/Transforms/InstCombine/out-of-bounds-indexes.ll
+++ b/llvm/test/Transforms/InstCombine/out-of-bounds-indexes.ll
@@ -4,17 +4,11 @@
 ; Check that we don't crash on unreasonable constant indexes
 
 define i32 @test_out_of_bounds(i32 %a, i1 %x, i1 %y) {
-; EXPENSIVE-OFF-LABEL: @test_out_of_bounds(
-; EXPENSIVE-OFF-NEXT:  entry:
-; EXPENSIVE-OFF-NEXT:    [[AND1:%.*]] = and i32 [[A:%.*]], 3
-; EXPENSIVE-OFF-NEXT:    tail call void @llvm.assume(i1 undef)
-; EXPENSIVE-OFF-NEXT:    ret i32 [[AND1]]
-;
-; EXPENSIVE-ON-LABEL: @test_out_of_bounds(
-; EXPENSIVE-ON-NEXT:  entry:
-; EXPENSIVE-ON-NEXT:    [[AND1:%.*]] = and i32 [[A:%.*]], 3
-; EXPENSIVE-ON-NEXT:    tail call void @llvm.assume(i1 false)
-; EXPENSIVE-ON-NEXT:    ret i32 [[AND1]]
+; CHECK-LABEL: @test_out_of_bounds(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[A:%.*]], 3
+; CHECK-NEXT:    tail call void @llvm.assume(i1 undef)
+; CHECK-NEXT:    ret i32 [[AND1]]
 ;
 entry:
   %and1 = and i32 %a, 3
@@ -25,15 +19,10 @@
 }
 
 define i128 @test_non64bit(i128 %a) {
-; EXPENSIVE-OFF-LABEL: @test_non64bit(
-; EXPENSIVE-OFF-NEXT:    [[AND1:%.*]] = and i128 [[A:%.*]], 3
-; EXPENSIVE-OFF-NEXT:    tail call void @llvm.assume(i1 undef)
-; EXPENSIVE-OFF-NEXT:    ret i128 [[AND1]]
-;
-; EXPENSIVE-ON-LABEL: @test_non64bit(
-; EXPENSIVE-ON-NEXT:    [[AND1:%.*]] = and i128 [[A:%.*]], 3
-; EXPENSIVE-ON-NEXT:    tail call void @llvm.assume(i1 false)
-; EXPENSIVE-ON-NEXT:    ret i128 [[AND1]]
+; CHECK-LABEL: @test_non64bit(
+; CHECK-NEXT:    [[AND1:%.*]] = and i128 [[A:%.*]], 3
+; CHECK-NEXT:    tail call void @llvm.assume(i1 undef)
+; CHECK-NEXT:    ret i128 [[AND1]]
 ;
   %and1 = and i128 %a, 3
   %B = lshr i128 %and1, -1
diff --git a/llvm/test/Transforms/InstCombine/phi-shifts.ll b/llvm/test/Transforms/InstCombine/phi-shifts.ll
--- a/llvm/test/Transforms/InstCombine/phi-shifts.ll
+++ b/llvm/test/Transforms/InstCombine/phi-shifts.ll
@@ -4,21 +4,13 @@
 
 ; OSS Fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15217
 define i64 @fuzz15217(i1 %cond, i8* %Ptr, i64 %Val) {
-; EXPENSIVE-OFF-LABEL: @fuzz15217(
-; EXPENSIVE-OFF-NEXT:  entry:
-; EXPENSIVE-OFF-NEXT:    br i1 [[COND:%.*]], label [[END:%.*]], label [[TWO:%.*]]
-; EXPENSIVE-OFF:       two:
-; EXPENSIVE-OFF-NEXT:    br label [[END]]
-; EXPENSIVE-OFF:       end:
-; EXPENSIVE-OFF-NEXT:    ret i64 undef
-;
-; EXPENSIVE-ON-LABEL: @fuzz15217(
-; EXPENSIVE-ON-NEXT:  entry:
-; EXPENSIVE-ON-NEXT:    br i1 [[COND:%.*]], label [[END:%.*]], label [[TWO:%.*]]
-; EXPENSIVE-ON:       two:
-; EXPENSIVE-ON-NEXT:    br label [[END]]
-; EXPENSIVE-ON:       end:
-; EXPENSIVE-ON-NEXT:    ret i64 0
+; CHECK-LABEL: @fuzz15217(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[COND:%.*]], label [[END:%.*]], label [[TWO:%.*]]
+; CHECK:       two:
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       end:
+; CHECK-NEXT:    ret i64 undef
 ;
 entry:
   br i1 %cond, label %end, label %two