diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 2af6ba5c81822..682005282d92a 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2471,25 +2471,7 @@ static bool isMustTailCall(Value *V) {
 }
 
 Instruction *InstCombinerImpl::visitReturnInst(ReturnInst &RI) {
-  if (RI.getNumOperands() == 0) // ret void
-    return nullptr;
-
-  Value *ResultOp = RI.getOperand(0);
-  Type *VTy = ResultOp->getType();
-  if (!VTy->isIntegerTy() || isa<Constant>(ResultOp))
-    return nullptr;
-
-  // Don't replace result of musttail calls.
-  if (isMustTailCall(ResultOp))
-    return nullptr;
-
-  // There might be assume intrinsics dominating this return that completely
-  // determine the value. If so, constant fold it.
-  KnownBits Known = computeKnownBits(ResultOp, 0, &RI);
-  if (Known.isConstant())
-    return replaceOperand(RI, 0,
-        Constant::getIntegerValue(VTy, Known.getConstant()));
-
+  // Nothing for now.
   return nullptr;
 }
 
diff --git a/llvm/test/Transforms/InstCombine/assume.ll b/llvm/test/Transforms/InstCombine/assume.ll
index 467ecec60a3f5..83ff0e3a392dd 100644
--- a/llvm/test/Transforms/InstCombine/assume.ll
+++ b/llvm/test/Transforms/InstCombine/assume.ll
@@ -1,6 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -passes=instcombine -S  -instcombine-infinite-loop-threshold=2  | FileCheck --check-prefixes=CHECK,DEFAULT %s
-; RUN: opt < %s -passes=instcombine --enable-knowledge-retention -S  -instcombine-infinite-loop-threshold=2  | FileCheck --check-prefixes=CHECK,BUNDLES %s
+; RUN: opt < %s -passes=instcombine -S  -instcombine-infinite-loop-threshold=3  | FileCheck --check-prefixes=CHECK,DEFAULT %s
+; RUN: opt < %s -passes=instcombine --enable-knowledge-retention -S  -instcombine-infinite-loop-threshold=3  | FileCheck --check-prefixes=CHECK,BUNDLES %s
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
@@ -60,7 +60,7 @@ define i32 @simple(i32 %a) #1 {
 ; CHECK-LABEL: @simple(
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[A:%.*]], 4
 ; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
-; CHECK-NEXT:    ret i32 4
+; CHECK-NEXT:    ret i32 [[A]]
 ;
   %cmp = icmp eq i32 %a, 4
   tail call void @llvm.assume(i1 %cmp)
@@ -204,7 +204,8 @@ define i32 @icmp1(i32 %a) #0 {
 ; CHECK-LABEL: @icmp1(
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], 5
 ; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP]])
-; CHECK-NEXT:    ret i32 1
+; CHECK-NEXT:    [[CONV:%.*]] = zext i1 [[CMP]] to i32
+; CHECK-NEXT:    ret i32 [[CONV]]
 ;
   %cmp = icmp sgt i32 %a, 5
   tail call void @llvm.assume(i1 %cmp)
@@ -231,7 +232,7 @@ define i1 @assume_not(i1 %cond) {
 ; CHECK-LABEL: @assume_not(
 ; CHECK-NEXT:    [[NOTCOND:%.*]] = xor i1 [[COND:%.*]], true
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[NOTCOND]])
-; CHECK-NEXT:    ret i1 false
+; CHECK-NEXT:    ret i1 [[COND]]
 ;
   %notcond = xor i1 %cond, true
   call void @llvm.assume(i1 %notcond)
@@ -382,10 +383,7 @@ define i1 @nonnull5(ptr %a) {
 
 define i32 @assumption_conflicts_with_known_bits(i32 %a, i32 %b) {
 ; 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
@@ -451,7 +449,7 @@ define i1 @nonnull3A(ptr %a, i1 %control) {
 ; DEFAULT:       taken:
 ; DEFAULT-NEXT:    [[CMP:%.*]] = icmp ne ptr [[LOAD]], null
 ; DEFAULT-NEXT:    call void @llvm.assume(i1 [[CMP]])
-; DEFAULT-NEXT:    ret i1 true
+; DEFAULT-NEXT:    ret i1 [[CMP]]
 ; DEFAULT:       not_taken:
 ; DEFAULT-NEXT:    [[RVAL_2:%.*]] = icmp sgt ptr [[LOAD]], null
 ; DEFAULT-NEXT:    ret i1 [[RVAL_2]]
@@ -487,7 +485,7 @@ define i1 @nonnull3B(ptr %a, i1 %control) {
 ; CHECK-NEXT:    [[LOAD:%.*]] = load ptr, ptr [[A:%.*]], align 8
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ne ptr [[LOAD]], null
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]]) [ "nonnull"(ptr [[LOAD]]) ]
-; CHECK-NEXT:    ret i1 true
+; CHECK-NEXT:    ret i1 [[CMP]]
 ; CHECK:       not_taken:
 ; CHECK-NEXT:    ret i1 [[CONTROL]]
 ;
diff --git a/llvm/test/Transforms/InstCombine/known-phi-br.ll b/llvm/test/Transforms/InstCombine/known-phi-br.ll
index 64d3344eb2066..1ad0ed42d8d34 100644
--- a/llvm/test/Transforms/InstCombine/known-phi-br.ll
+++ b/llvm/test/Transforms/InstCombine/known-phi-br.ll
@@ -15,7 +15,8 @@ define i64 @limit_i64_eq_7(i64 %x) {
 ; CHECK:       body:
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    ret i64 7
+; CHECK-NEXT:    [[RES:%.*]] = phi i64 [ [[X]], [[ENTRY:%.*]] ], [ 7, [[BODY]] ]
+; CHECK-NEXT:    ret i64 [[RES]]
 ;
 entry:
   %cmp = icmp eq i64 %x, 7
@@ -37,7 +38,8 @@ define i64 @limit_i64_ne_255(i64 %x) {
 ; CHECK:       body:
 ; CHECK-NEXT:    br label [[END]]
 ; CHECK:       end:
-; CHECK-NEXT:    ret i64 255
+; CHECK-NEXT:    [[RES:%.*]] = phi i64 [ [[X]], [[ENTRY:%.*]] ], [ 255, [[BODY]] ]
+; CHECK-NEXT:    ret i64 [[RES]]
 ;
 entry:
   %cmp = icmp ne i64 %x, 255
diff --git a/llvm/test/Transforms/InstCombine/zext-or-icmp.ll b/llvm/test/Transforms/InstCombine/zext-or-icmp.ll
index 655c2e7c083a9..7d57cd21f4e83 100644
--- a/llvm/test/Transforms/InstCombine/zext-or-icmp.ll
+++ b/llvm/test/Transforms/InstCombine/zext-or-icmp.ll
@@ -251,7 +251,7 @@ define i1 @PR51762(ptr %i, i32 %t0, i16 %t1, ptr %p, ptr %d, ptr %f, i32 %p2, i1
 ; CHECK-NEXT:    store i32 [[SROA38]], ptr [[D]], align 8
 ; CHECK-NEXT:    [[R:%.*]] = icmp ult i64 [[INSERT_INSERT41]], [[CONV19]]
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[R]])
-; CHECK-NEXT:    ret i1 true
+; CHECK-NEXT:    ret i1 [[R]]
 ;
 entry:
   br label %for.cond