diff --git a/compiler/ir/backend.jvm/entrypoint/src/org/jetbrains/kotlin/backend/jvm/JvmIrSerializerImpl.kt b/compiler/ir/backend.jvm/entrypoint/src/org/jetbrains/kotlin/backend/jvm/JvmIrSerializerImpl.kt
index 1e78174f2b9..c3bb85d7c14 100644
--- a/compiler/ir/backend.jvm/entrypoint/src/org/jetbrains/kotlin/backend/jvm/JvmIrSerializerImpl.kt
+++ b/compiler/ir/backend.jvm/entrypoint/src/org/jetbrains/kotlin/backend/jvm/JvmIrSerializerImpl.kt
@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.backend.jvm
 
 import org.jetbrains.kotlin.backend.common.serialization.DeclarationTable
+import org.jetbrains.kotlin.backend.jvm.lower.getFileClassInfo
 import org.jetbrains.kotlin.backend.jvm.serialization.JvmGlobalDeclarationTable
 import org.jetbrains.kotlin.backend.jvm.serialization.JvmIrSerializerSession
 import org.jetbrains.kotlin.config.CompilerConfiguration
@@ -14,25 +15,29 @@ import org.jetbrains.kotlin.config.JvmSerializeIrMode
 import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.ir.util.IrMessageLogger
+import org.jetbrains.kotlin.name.FqName
 
 class JvmIrSerializerImpl(private val configuration: CompilerConfiguration) : JvmIrSerializer {
 
     private val declarationTable = DeclarationTable(JvmGlobalDeclarationTable())
 
     override fun serializeIrFile(irFile: IrFile): ByteArray? {
-        return makeSerializerSession().serializeJvmIrFile(irFile)?.toByteArray()
+        val fileClassFqName = irFile.getFileClassInfo().fileClassFqName
+        return makeSerializerSession(fileClassFqName).serializeJvmIrFile(irFile)?.toByteArray()
     }
 
     override fun serializeTopLevelIrClass(irClass: IrClass): ByteArray? {
         assert(irClass.parent is IrFile)
-        return makeSerializerSession().serializeTopLevelClass(irClass)?.toByteArray()
+        val fileClassFqName = (irClass.parent as IrFile).getFileClassInfo().fileClassFqName
+        return makeSerializerSession(fileClassFqName).serializeTopLevelClass(irClass)?.toByteArray()
     }
 
-    private fun makeSerializerSession() =
+    private fun makeSerializerSession(fileClassFqName: FqName) =
         JvmIrSerializerSession(
             configuration.get(IrMessageLogger.IR_MESSAGE_LOGGER) ?: IrMessageLogger.None,
             declarationTable,
             mutableMapOf(),
-            configuration.get(JVMConfigurationKeys.SERIALIZE_IR) ?: JvmSerializeIrMode.NONE
+            configuration.get(JVMConfigurationKeys.SERIALIZE_IR) ?: JvmSerializeIrMode.NONE,
+            fileClassFqName
         )
 }
\ No newline at end of file
diff --git a/compiler/ir/serialization.jvm/src/JvmIr.proto b/compiler/ir/serialization.jvm/src/JvmIr.proto
index b407045fafb..e8b88e795ca 100644
--- a/compiler/ir/serialization.jvm/src/JvmIr.proto
+++ b/compiler/ir/serialization.jvm/src/JvmIr.proto
@@ -21,4 +21,5 @@ message ClassOrFile {
   repeated string string = 4;
   repeated XStatementOrExpression body = 5;
   repeated string debug_info = 6;
+  required string file_facade_fq_name = 7;
 }
diff --git a/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/JvmIrSerializerSession.kt b/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/JvmIrSerializerSession.kt
index d4ecc0f8e82..0df40f8c33a 100644
--- a/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/JvmIrSerializerSession.kt
+++ b/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/JvmIrSerializerSession.kt
@@ -16,6 +16,7 @@ import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.util.IrMessageLogger
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
+import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.synthetic.isVisibleOutside
 
 class JvmIrSerializerSession(
@@ -23,6 +24,7 @@ class JvmIrSerializerSession(
     private val declarationTable: DeclarationTable,
     expectDescriptorToSymbol: MutableMap<DeclarationDescriptor, IrSymbol>,
     private val mode: JvmSerializeIrMode,
+    private val fileClassFqName: FqName,
     skipExpects: Boolean = false,
 ) : IrFileSerializer(
     messageLogger, declarationTable, expectDescriptorToSymbol, CompatibilityMode.CURRENT,
@@ -50,6 +52,7 @@ class JvmIrSerializerSession(
         if (!anySaved) return null
 
         serializeAuxTables(proto)
+        proto.fileFacadeFqName = fileClassFqName.asString()
 
         return proto.build()
     }
@@ -62,6 +65,8 @@ class JvmIrSerializerSession(
             }
         }
         serializeAuxTables(proto)
+        proto.fileFacadeFqName = fileClassFqName.asString()
+
         return proto.build()
     }
 
diff --git a/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/deserializeLazyDeclarations.kt b/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/deserializeLazyDeclarations.kt
index 4e1c36e0ce8..8727989dcd9 100644
--- a/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/deserializeLazyDeclarations.kt
+++ b/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/deserializeLazyDeclarations.kt
@@ -62,7 +62,8 @@ fun deserializeFromByteArray(
 
     // Only needed for local signature computation.
     val dummyIrFile = IrFileImpl(NaiveSourceBasedFileEntryImpl("<unknown>"), IrFileSymbolImpl(), toplevelParent.packageFqName!!)
-    val dummyFileSignature = IdSignature.FileSignature(Any(), toplevelParent.packageFqName!!, "<unknown>")
+    // On JVM, file-scope private declarations are uniquely identified by file facade's fq name.
+    val dummyFileSignature = IdSignature.FileSignature(irProto.fileFacadeFqName, toplevelParent.packageFqName!!, "<unknown>")
 
     val symbolDeserializer = IrSymbolDeserializer(
         symbolTable,
diff --git a/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/proto/JvmIr.java b/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/proto/JvmIr.java
index 8a1dca4c2c8..b4f4bae769e 100644
--- a/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/proto/JvmIr.java
+++ b/compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/proto/JvmIr.java
@@ -690,6 +690,20 @@ public final class JvmIr {
      */
     org.jetbrains.kotlin.protobuf.ByteString
         getDebugInfoBytes(int index);
+
+    /**
+     * <code>required string file_facade_fq_name = 7;</code>
+     */
+    boolean hasFileFacadeFqName();
+    /**
+     * <code>required string file_facade_fq_name = 7;</code>
+     */
+    java.lang.String getFileFacadeFqName();
+    /**
+     * <code>required string file_facade_fq_name = 7;</code>
+     */
+    org.jetbrains.kotlin.protobuf.ByteString
+        getFileFacadeFqNameBytes();
   }
   /**
    * Protobuf type {@code org.jetbrains.kotlin.backend.jvm.serialization.proto.ClassOrFile}
@@ -791,6 +805,12 @@ public final class JvmIr {
               debugInfo_.add(bs);
               break;
             }
+            case 58: {
+              org.jetbrains.kotlin.protobuf.ByteString bs = input.readBytes();
+              bitField0_ |= 0x00000001;
+              fileFacadeFqName_ = bs;
+              break;
+            }
           }
         }
       } catch (org.jetbrains.kotlin.protobuf.InvalidProtocolBufferException e) {
@@ -842,6 +862,7 @@ public final class JvmIr {
       return PARSER;
     }
 
+    private int bitField0_;
     public static final int DECLARATION_FIELD_NUMBER = 1;
     private java.util.List<org.jetbrains.kotlin.backend.common.serialization.proto.IrDeclaration> declaration_;
     /**
@@ -1040,6 +1061,48 @@ public final class JvmIr {
       return debugInfo_.getByteString(index);
     }
 
+    public static final int FILE_FACADE_FQ_NAME_FIELD_NUMBER = 7;
+    private java.lang.Object fileFacadeFqName_;
+    /**
+     * <code>required string file_facade_fq_name = 7;</code>
+     */
+    public boolean hasFileFacadeFqName() {
+      return ((bitField0_ & 0x00000001) == 0x00000001);
+    }
+    /**
+     * <code>required string file_facade_fq_name = 7;</code>
+     */
+    public java.lang.String getFileFacadeFqName() {
+      java.lang.Object ref = fileFacadeFqName_;
+      if (ref instanceof java.lang.String) {
+        return (java.lang.String) ref;
+      } else {
+        org.jetbrains.kotlin.protobuf.ByteString bs = 
+            (org.jetbrains.kotlin.protobuf.ByteString) ref;
+        java.lang.String s = bs.toStringUtf8();
+        if (bs.isValidUtf8()) {
+          fileFacadeFqName_ = s;
+        }
+        return s;
+      }
+    }
+    /**
+     * <code>required string file_facade_fq_name = 7;</code>
+     */
+    public org.jetbrains.kotlin.protobuf.ByteString
+        getFileFacadeFqNameBytes() {
+      java.lang.Object ref = fileFacadeFqName_;
+      if (ref instanceof java.lang.String) {
+        org.jetbrains.kotlin.protobuf.ByteString b = 
+            org.jetbrains.kotlin.protobuf.ByteString.copyFromUtf8(
+                (java.lang.String) ref);
+        fileFacadeFqName_ = b;
+        return b;
+      } else {
+        return (org.jetbrains.kotlin.protobuf.ByteString) ref;
+      }
+    }
+
     private void initFields() {
       declaration_ = java.util.Collections.emptyList();
       type_ = java.util.Collections.emptyList();
@@ -1047,6 +1110,7 @@ public final class JvmIr {
       string_ = org.jetbrains.kotlin.protobuf.LazyStringArrayList.EMPTY;
       body_ = java.util.Collections.emptyList();
       debugInfo_ = org.jetbrains.kotlin.protobuf.LazyStringArrayList.EMPTY;
+      fileFacadeFqName_ = "";
     }
     private byte memoizedIsInitialized = -1;
     public final boolean isInitialized() {
@@ -1054,6 +1118,10 @@ public final class JvmIr {
       if (isInitialized == 1) return true;
       if (isInitialized == 0) return false;
 
+      if (!hasFileFacadeFqName()) {
+        memoizedIsInitialized = 0;
+        return false;
+      }
       for (int i = 0; i < getDeclarationCount(); i++) {
         if (!getDeclaration(i).isInitialized()) {
           memoizedIsInitialized = 0;
@@ -1103,6 +1171,9 @@ public final class JvmIr {
       for (int i = 0; i < debugInfo_.size(); i++) {
         output.writeBytes(6, debugInfo_.getByteString(i));
       }
+      if (((bitField0_ & 0x00000001) == 0x00000001)) {
+        output.writeBytes(7, getFileFacadeFqNameBytes());
+      }
       output.writeRawBytes(unknownFields);
     }
 
@@ -1146,6 +1217,10 @@ public final class JvmIr {
         size += dataSize;
         size += 1 * getDebugInfoList().size();
       }
+      if (((bitField0_ & 0x00000001) == 0x00000001)) {
+        size += org.jetbrains.kotlin.protobuf.CodedOutputStream
+          .computeBytesSize(7, getFileFacadeFqNameBytes());
+      }
       size += unknownFields.size();
       memoizedSerializedSize = size;
       return size;
@@ -1252,6 +1327,8 @@ public final class JvmIr {
         bitField0_ = (bitField0_ & ~0x00000010);
         debugInfo_ = org.jetbrains.kotlin.protobuf.LazyStringArrayList.EMPTY;
         bitField0_ = (bitField0_ & ~0x00000020);
+        fileFacadeFqName_ = "";
+        bitField0_ = (bitField0_ & ~0x00000040);
         return this;
       }
 
@@ -1274,6 +1351,7 @@ public final class JvmIr {
       public org.jetbrains.kotlin.backend.jvm.serialization.proto.JvmIr.ClassOrFile buildPartial() {
         org.jetbrains.kotlin.backend.jvm.serialization.proto.JvmIr.ClassOrFile result = new org.jetbrains.kotlin.backend.jvm.serialization.proto.JvmIr.ClassOrFile(this);
         int from_bitField0_ = bitField0_;
+        int to_bitField0_ = 0;
         if (((bitField0_ & 0x00000001) == 0x00000001)) {
           declaration_ = java.util.Collections.unmodifiableList(declaration_);
           bitField0_ = (bitField0_ & ~0x00000001);
@@ -1304,6 +1382,11 @@ public final class JvmIr {
           bitField0_ = (bitField0_ & ~0x00000020);
         }
         result.debugInfo_ = debugInfo_;
+        if (((from_bitField0_ & 0x00000040) == 0x00000040)) {
+          to_bitField0_ |= 0x00000001;
+        }
+        result.fileFacadeFqName_ = fileFacadeFqName_;
+        result.bitField0_ = to_bitField0_;
         return result;
       }
 
@@ -1368,6 +1451,11 @@ public final class JvmIr {
             debugInfo_.addAll(other.debugInfo_);
           }
           
+        }
+        if (other.hasFileFacadeFqName()) {
+          bitField0_ |= 0x00000040;
+          fileFacadeFqName_ = other.fileFacadeFqName_;
+          
         }
         setUnknownFields(
             getUnknownFields().concat(other.unknownFields));
@@ -1375,6 +1463,10 @@ public final class JvmIr {
       }
 
       public final boolean isInitialized() {
+        if (!hasFileFacadeFqName()) {
+          
+          return false;
+        }
         for (int i = 0; i < getDeclarationCount(); i++) {
           if (!getDeclaration(i).isInitialized()) {
             
@@ -2107,6 +2199,82 @@ public final class JvmIr {
         return this;
       }
 
+      private java.lang.Object fileFacadeFqName_ = "";
+      /**
+       * <code>required string file_facade_fq_name = 7;</code>
+       */
+      public boolean hasFileFacadeFqName() {
+        return ((bitField0_ & 0x00000040) == 0x00000040);
+      }
+      /**
+       * <code>required string file_facade_fq_name = 7;</code>
+       */
+      public java.lang.String getFileFacadeFqName() {
+        java.lang.Object ref = fileFacadeFqName_;
+        if (!(ref instanceof java.lang.String)) {
+          org.jetbrains.kotlin.protobuf.ByteString bs =
+              (org.jetbrains.kotlin.protobuf.ByteString) ref;
+          java.lang.String s = bs.toStringUtf8();
+          if (bs.isValidUtf8()) {
+            fileFacadeFqName_ = s;
+          }
+          return s;
+        } else {
+          return (java.lang.String) ref;
+        }
+      }
+      /**
+       * <code>required string file_facade_fq_name = 7;</code>
+       */
+      public org.jetbrains.kotlin.protobuf.ByteString
+          getFileFacadeFqNameBytes() {
+        java.lang.Object ref = fileFacadeFqName_;
+        if (ref instanceof String) {
+          org.jetbrains.kotlin.protobuf.ByteString b = 
+              org.jetbrains.kotlin.protobuf.ByteString.copyFromUtf8(
+                  (java.lang.String) ref);
+          fileFacadeFqName_ = b;
+          return b;
+        } else {
+          return (org.jetbrains.kotlin.protobuf.ByteString) ref;
+        }
+      }
+      /**
+       * <code>required string file_facade_fq_name = 7;</code>
+       */
+      public Builder setFileFacadeFqName(
+          java.lang.String value) {
+        if (value == null) {
+    throw new NullPointerException();
+  }
+  bitField0_ |= 0x00000040;
+        fileFacadeFqName_ = value;
+        
+        return this;
+      }
+      /**
+       * <code>required string file_facade_fq_name = 7;</code>
+       */
+      public Builder clearFileFacadeFqName() {
+        bitField0_ = (bitField0_ & ~0x00000040);
+        fileFacadeFqName_ = getDefaultInstance().getFileFacadeFqName();
+        
+        return this;
+      }
+      /**
+       * <code>required string file_facade_fq_name = 7;</code>
+       */
+      public Builder setFileFacadeFqNameBytes(
+          org.jetbrains.kotlin.protobuf.ByteString value) {
+        if (value == null) {
+    throw new NullPointerException();
+  }
+  bitField0_ |= 0x00000040;
+        fileFacadeFqName_ = value;
+        
+        return this;
+      }
+
       // @@protoc_insertion_point(builder_scope:org.jetbrains.kotlin.backend.jvm.serialization.proto.ClassOrFile)
     }