diff --git a/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java b/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java
index 7b5e8f31a46..bd050cf8720 100644
--- a/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java
+++ b/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java
@@ -3950,6 +3950,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             runTest("compiler/testData/codegen/box/casts/nullableSafeCastToTypeParameterWithInterfaceUpperBound.kt");
         }
 
+        @Test
+        @TestMetadata("objectToPrimitiveWithAssertion.kt")
+        public void testObjectToPrimitiveWithAssertion() throws Exception {
+            runTest("compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt");
+        }
+
         @Test
         @TestMetadata("unitAsAny.kt")
         public void testUnitAsAny() throws Exception {
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt
index 6d5713ad716..aac40d055c7 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt
@@ -326,7 +326,6 @@ private val jvmFilePhases = listOf(
     polymorphicSignaturePhase,
     varargPhase,
     arrayConstructorPhase,
-    checkNotNullPhase,
 
     lateinitNullableFieldsPhase,
     lateinitDeclarationLoweringPhase,
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/intrinsics/IrCheckNotNull.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/intrinsics/IrCheckNotNull.kt
new file mode 100644
index 00000000000..e79c83b380d
--- /dev/null
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/intrinsics/IrCheckNotNull.kt
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.backend.jvm.intrinsics
+
+import org.jetbrains.kotlin.backend.jvm.codegen.*
+import org.jetbrains.kotlin.codegen.AsmUtil
+import org.jetbrains.kotlin.codegen.intrinsics.IntrinsicMethods
+import org.jetbrains.kotlin.ir.expressions.IrFunctionAccessExpression
+import org.jetbrains.kotlin.ir.types.IrType
+import org.jetbrains.org.objectweb.asm.Label
+import org.jetbrains.org.objectweb.asm.Type
+
+private fun ExpressionCodegen.checkTopValueForNull() {
+    mv.dup()
+    if (state.unifiedNullChecks) {
+        mv.invokestatic(IntrinsicMethods.INTRINSICS_CLASS_NAME, "checkNotNull", "(Ljava/lang/Object;)V", false)
+    } else {
+        val ifNonNullLabel = Label()
+        mv.ifnonnull(ifNonNullLabel)
+        mv.invokestatic(IntrinsicMethods.INTRINSICS_CLASS_NAME, "throwNpe", "()V", false)
+        mv.mark(ifNonNullLabel)
+    }
+}
+
+object IrCheckNotNull : IntrinsicMethod() {
+    override fun invoke(expression: IrFunctionAccessExpression, codegen: ExpressionCodegen, data: BlockInfo): PromisedValue? {
+        val arg0 = expression.getValueArgument(0)!!.accept(codegen, data)
+        if (AsmUtil.isPrimitive(arg0.type)) return arg0
+        return object : PromisedValue(codegen, arg0.type, expression.type) {
+            override fun materializeAt(target: Type, irTarget: IrType, castForReified: Boolean) =
+                arg0.materialized().also { codegen.checkTopValueForNull() }.materializeAt(target, irTarget, castForReified)
+
+            override fun discard() =
+                arg0.materialized().also { codegen.checkTopValueForNull() }.discard()
+        }
+    }
+}
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/intrinsics/IrIntrinsicMethods.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/intrinsics/IrIntrinsicMethods.kt
index bce051b46e4..221e0d86f47 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/intrinsics/IrIntrinsicMethods.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/intrinsics/IrIntrinsicMethods.kt
@@ -110,6 +110,7 @@ class IrIntrinsicMethods(val irBuiltIns: IrBuiltIns, val symbols: JvmSymbols) {
                 irBuiltIns.booleanNotSymbol.toKey()!! to Not,
                 irBuiltIns.noWhenBranchMatchedExceptionSymbol.toKey()!! to IrNoWhenBranchMatchedException,
                 irBuiltIns.illegalArgumentExceptionSymbol.toKey()!! to IrIllegalArgumentException,
+                irBuiltIns.checkNotNullSymbol.toKey()!! to IrCheckNotNull,
                 irBuiltIns.andandSymbol.toKey()!! to AndAnd,
                 irBuiltIns.ororSymbol.toKey()!! to OrOr,
                 irBuiltIns.dataClassArrayMemberHashCodeSymbol.toKey()!! to IrDataClassArrayMemberHashCode,
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/CheckNotNullLowering.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/CheckNotNullLowering.kt
deleted file mode 100644
index 9205857095f..00000000000
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/CheckNotNullLowering.kt
+++ /dev/null
@@ -1,56 +0,0 @@
-/*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
-package org.jetbrains.kotlin.backend.jvm.lower
-
-import org.jetbrains.kotlin.backend.common.FileLoweringPass
-import org.jetbrains.kotlin.backend.common.IrElementTransformerVoidWithContext
-import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
-import org.jetbrains.kotlin.backend.common.lower.irIfThen
-import org.jetbrains.kotlin.backend.common.phaser.makeIrFilePhase
-import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
-import org.jetbrains.kotlin.ir.builders.*
-import org.jetbrains.kotlin.ir.declarations.IrFile
-import org.jetbrains.kotlin.ir.expressions.IrCall
-import org.jetbrains.kotlin.ir.expressions.IrExpression
-import org.jetbrains.kotlin.ir.expressions.IrGetValue
-
-internal val checkNotNullPhase = makeIrFilePhase(
-    ::CheckNotNullLowering,
-    name = "CheckNotNullLowering",
-    description = "Lower calls to the CHECK_NOT_NULL intrinsic, which are generated by psi2ir for \"!!\" expressions."
-)
-
-private class CheckNotNullLowering(private val backendContext: JvmBackendContext) : FileLoweringPass, IrElementTransformerVoidWithContext() {
-    override fun lower(irFile: IrFile) = irFile.transformChildrenVoid()
-
-    override fun visitCall(expression: IrCall): IrExpression {
-        if (expression.symbol != backendContext.irBuiltIns.checkNotNullSymbol)
-            return super.visitCall(expression)
-
-        expression.transformChildrenVoid()
-        return backendContext.createIrBuilder(currentScope!!.scope.scopeOwnerSymbol, expression.startOffset, expression.endOffset).irBlock {
-            val valueArgument = expression.getValueArgument(0)!!
-
-            // For a null-check on a variable we should not introduce a temporary, since null checks are
-            // optimized by RedundantNullCheckMethodTransformer, which remembers that the argument variable
-            // is non-nullable if this call succeeds.
-            val argument = if (valueArgument is IrGetValue) valueArgument.symbol.owner else irTemporary(valueArgument)
-
-            // Starting with Kotlin 1.4 null-checks are lowered to calls to the "checkNotNull" intrinsic, which
-            // throws a NullPointerException on failure. Prior to Kotlin 1.4 we instead inline the null-check and
-            // call the "throwNpe" intrinsic on failure which throws a KotlinNullPointerException.
-            if (backendContext.state.unifiedNullChecks) {
-                +irCall(backendContext.ir.symbols.checkNotNull).apply {
-                    putValueArgument(0, irGet(argument))
-                }
-            } else {
-                +irIfThen(irEqualsNull(irGet(argument)), irCall(backendContext.ir.symbols.throwNpe))
-            }
-
-            +irImplicitCast(irGet(argument), expression.type)
-        }
-    }
-}
diff --git a/compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt b/compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt
new file mode 100644
index 00000000000..1ef8e0033e4
--- /dev/null
+++ b/compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt
@@ -0,0 +1,8 @@
+// IGNORE_BACKEND: JS, JS_IR, WASM
+@Suppress("UNCHECKED_CAST")
+fun <T> f() = 1L as T
+
+fun box(): String {
+    val x: Int = f()!! // T = Int?, but the cast succeeds because it's immediately upcasted to Number
+    return if (x == 1) "OK" else "fail: $x"
+}
diff --git a/compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing1.kt b/compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing1.kt
index 6917d999aea..896b784b78c 100644
--- a/compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing1.kt
+++ b/compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing1.kt
@@ -1,4 +1,5 @@
-// NB '!!' uses Intrinsics.throwNpe/checkNotNull
+// NB '!!' uses Intrinsics.throwNpe/checkNotNull, but IR follows it with ATHROW
+// while the old backend returns null from `exit`
 inline fun exit(): Nothing = null!!
 
 fun box(): String {
@@ -13,4 +14,7 @@ fun box(): String {
     return a
 }
 
+// JVM_TEMPLATES
 // 1 ATHROW
+// JVM_IR_TEMPLATES
+// 2 ATHROW
diff --git a/compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing3.kt b/compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing3.kt
index f39c50f633f..0bdfb85c061 100644
--- a/compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing3.kt
+++ b/compiler/testData/codegen/bytecodeText/inline/inlineReturnsNothing3.kt
@@ -1,3 +1,5 @@
+// NB '!!' uses Intrinsics.throwNpe/checkNotNull, but IR follows it with ATHROW
+// while the old backend returns null from `exit`
 inline fun exit(): Nothing = null!!
 inline fun exita(): Nothing = exit() // ATHROW
 inline fun exitb(): Nothing = exita() // ATHROW
@@ -14,4 +16,7 @@ fun box(): String {
     return a
 }
 
-// 4 ATHROW
\ No newline at end of file
+// JVM_TEMPLATES
+// 4 ATHROW
+// JVM_IR_TEMPLATES
+// 5 ATHROW
diff --git a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java
index 90aca518941..815cbdc35cf 100644
--- a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java
+++ b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java
@@ -3950,6 +3950,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/casts/nullableSafeCastToTypeParameterWithInterfaceUpperBound.kt");
         }
 
+        @Test
+        @TestMetadata("objectToPrimitiveWithAssertion.kt")
+        public void testObjectToPrimitiveWithAssertion() throws Exception {
+            runTest("compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt");
+        }
+
         @Test
         @TestMetadata("unitAsAny.kt")
         public void testUnitAsAny() throws Exception {
diff --git a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java
index 25715caf6a5..ed6db17f630 100644
--- a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java
+++ b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java
@@ -3950,6 +3950,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/casts/nullableSafeCastToTypeParameterWithInterfaceUpperBound.kt");
         }
 
+        @Test
+        @TestMetadata("objectToPrimitiveWithAssertion.kt")
+        public void testObjectToPrimitiveWithAssertion() throws Exception {
+            runTest("compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt");
+        }
+
         @Test
         @TestMetadata("unitAsAny.kt")
         public void testUnitAsAny() throws Exception {
diff --git a/compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java b/compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java
index 7204ccccc58..f6f0a36327d 100644
--- a/compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java
+++ b/compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java
@@ -3450,6 +3450,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/casts/nullableSafeCastToTypeParameterWithInterfaceUpperBound.kt");
         }
 
+        @TestMetadata("objectToPrimitiveWithAssertion.kt")
+        public void testObjectToPrimitiveWithAssertion() throws Exception {
+            runTest("compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt");
+        }
+
         @TestMetadata("unitAsAny.kt")
         public void testUnitAsAny() throws Exception {
             runTest("compiler/testData/codegen/box/casts/unitAsAny.kt");
diff --git a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java
index 0dd027f1bd1..8229dae8eda 100644
--- a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java
+++ b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java
@@ -2625,6 +2625,11 @@ public class IrJsCodegenBoxES6TestGenerated extends AbstractIrJsCodegenBoxES6Tes
             runTest("compiler/testData/codegen/box/casts/nullableSafeCastToTypeParameterWithInterfaceUpperBound.kt");
         }
 
+        @TestMetadata("objectToPrimitiveWithAssertion.kt")
+        public void testObjectToPrimitiveWithAssertion() throws Exception {
+            runTest("compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt");
+        }
+
         @TestMetadata("unitAsAny.kt")
         public void testUnitAsAny() throws Exception {
             runTest("compiler/testData/codegen/box/casts/unitAsAny.kt");
diff --git a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java
index 5b54c57e440..13371c5f6c6 100644
--- a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java
+++ b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java
@@ -2625,6 +2625,11 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/casts/nullableSafeCastToTypeParameterWithInterfaceUpperBound.kt");
         }
 
+        @TestMetadata("objectToPrimitiveWithAssertion.kt")
+        public void testObjectToPrimitiveWithAssertion() throws Exception {
+            runTest("compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt");
+        }
+
         @TestMetadata("unitAsAny.kt")
         public void testUnitAsAny() throws Exception {
             runTest("compiler/testData/codegen/box/casts/unitAsAny.kt");
diff --git a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
index f254c22f8b3..9d6d4e65113 100644
--- a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
+++ b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
@@ -2625,6 +2625,11 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/casts/nullableSafeCastToTypeParameterWithInterfaceUpperBound.kt");
         }
 
+        @TestMetadata("objectToPrimitiveWithAssertion.kt")
+        public void testObjectToPrimitiveWithAssertion() throws Exception {
+            runTest("compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt");
+        }
+
         @TestMetadata("unitAsAny.kt")
         public void testUnitAsAny() throws Exception {
             runTest("compiler/testData/codegen/box/casts/unitAsAny.kt");
diff --git a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/wasm/semantics/IrCodegenBoxWasmTestGenerated.java b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/wasm/semantics/IrCodegenBoxWasmTestGenerated.java
index e200bf51802..377cd120450 100644
--- a/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/wasm/semantics/IrCodegenBoxWasmTestGenerated.java
+++ b/js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/wasm/semantics/IrCodegenBoxWasmTestGenerated.java
@@ -1820,6 +1820,11 @@ public class IrCodegenBoxWasmTestGenerated extends AbstractIrCodegenBoxWasmTest
             runTest("compiler/testData/codegen/box/casts/lambdaToUnitCast.kt");
         }
 
+        @TestMetadata("objectToPrimitiveWithAssertion.kt")
+        public void testObjectToPrimitiveWithAssertion() throws Exception {
+            runTest("compiler/testData/codegen/box/casts/objectToPrimitiveWithAssertion.kt");
+        }
+
         @TestMetadata("compiler/testData/codegen/box/casts/functions")
         @TestDataPath("$PROJECT_ROOT")
         @RunWith(JUnit3RunnerWithInners.class)