diff --git a/ide/buildlazdialog.pas b/ide/buildlazdialog.pas
index 017063dc21..f0a4c130f9 100644
--- a/ide/buildlazdialog.pas
+++ b/ide/buildlazdialog.pas
@@ -200,8 +200,10 @@ type
     function ShowConfigBuildLazDlg(AProfiles: TBuildLazarusProfiles;
       ADisableCompilation: Boolean): TModalResult;
     function MakeLazarus(Profile: TBuildLazarusProfile; Flags: TBuildLazarusFlags): TModalResult;
+    function MakeIDEUsingLazbuild(Clean: boolean): TModalResult;
     function IsWriteProtected(Profile: TBuildLazarusProfile): Boolean;
     function SaveIDEMakeOptions(Profile: TBuildLazarusProfile; Flags: TBuildLazarusFlags): TModalResult;
+    function SearchMakeExe(Interactive: boolean): string;
   public
     property PackageOptions: string read fPackageOptions write fPackageOptions;
     property ProfileChanged: boolean read fProfileChanged write fProfileChanged;
@@ -455,18 +457,7 @@ begin
     if s<>'' then
       EnvironmentOverrides.Values['PP']:=s;
 
-    Executable:=EnvironmentOptions.GetParsedMakeFilename;
-    if (Executable<>'') and (not FileExistsUTF8(Executable)) then
-      Executable:=FindDefaultExecutablePath(Executable);
-    if (Executable='') or (not FileExistsUTF8(Executable)) then begin
-      Executable:=FindDefaultMakePath;
-      if (Executable='') or (not FileExistsUTF8(Executable)) then begin
-        IDEMessageDialog(lisMakeNotFound,
-          Format(lisTheProgramMakeWasNotFoundThisToolIsNeededToBuildLa, [LineEnding]),
-          mtError, [mbCancel]);
-        exit;
-      end;
-    end;
+    Executable:=SearchMakeExe(true);
 
     // add -w option to print leaving/entering messages of "make"
     AddCmdLineParam('-w',false);
@@ -564,6 +555,99 @@ begin
   end;
 end;
 
+function TLazarusBuilder.MakeIDEUsingLazbuild(Clean: boolean): TModalResult;
+var
+  s, MakeExe, LazbuildExe: String;
+  Tool: TAbstractExternalTool;
+  EnvironmentOverrides: TStringList;
+begin
+  Result:=mrCancel;
+
+  EnvironmentOverrides:=TStringList.Create;
+  try
+    EnvironmentOverrides.Values['LANG']:= 'en_US';
+    s:=EnvironmentOptions.GetParsedCompilerFilename;
+    if s<>'' then
+      EnvironmentOverrides.Values['PP']:=s;
+
+    MakeExe:=SearchMakeExe(true);
+    fWorkingDir:=EnvironmentOptions.GetParsedLazarusDirectory;
+    if not CheckDirectoryWritable(fWorkingDir) then
+      exit;
+
+    // clean up
+    if Clean then
+    begin
+      Tool:=ExternalToolList.Add('make distclean');
+      Tool.Reference(Self,ClassName);
+      try
+        Tool.Data:=TIDEExternalToolData.Create(IDEToolCompileIDE,'make distclean',
+          MakeExe);
+        Tool.FreeData:=true;
+        Tool.Process.Executable:=MakeExe;
+        Tool.Process.Parameters.Add('distclean');
+        Tool.Process.CurrentDirectory:=fWorkingDir;
+        Tool.AddParsers(SubToolMake);
+        Tool.EnvironmentOverrides:=EnvironmentOverrides;
+        Tool.Execute;
+        Tool.WaitForExit;
+        if Tool.ErrorMessage<>'' then
+          exit(mrCancel);
+      finally
+        Tool.Release(Self);
+      end;
+    end;
+
+    // build lazbuild
+    Tool:=ExternalToolList.Add('make lazbuild');
+    Tool.Reference(Self,ClassName);
+    try
+      Tool.Data:=TIDEExternalToolData.Create(IDEToolCompileIDE,'make lazbuild',
+        MakeExe);
+      Tool.FreeData:=true;
+      Tool.Process.Executable:=MakeExe;
+      Tool.Process.Parameters.Add('lazbuild');
+      Tool.AddParsers(SubToolFPC);
+      Tool.AddParsers(SubToolMake);
+      Tool.Process.CurrentDirectory:=fWorkingDir;
+      Tool.EnvironmentOverrides:=EnvironmentOverrides;
+      Tool.Execute;
+      Tool.WaitForExit;
+      if Tool.ErrorMessage<>'' then
+        exit(mrCancel);
+    finally
+      Tool.Release(Self);
+    end;
+
+    // build the IDE using lazbuild
+    LazbuildExe:=AppendPathDelim(fWorkingDir)+'lazbuild'+GetExeExt;
+    Tool:=ExternalToolList.Add('lazbuild --useride=');
+    Tool.Reference(Self,ClassName);
+    try
+      Tool.Data:=TIDEExternalToolData.Create(IDEToolCompileIDE,'lazbuild --user-ide=',
+        MakeExe);
+      Tool.FreeData:=true;
+      Tool.Process.Executable:=LazbuildExe;
+      Tool.Process.Parameters.Add('--user-ide=');
+      Tool.Process.Parameters.Add('--lazarusdir=.');
+      Tool.Process.Parameters.Add('--pcp='+GetPrimaryConfigPath);
+      Tool.AddParsers(SubToolFPC);
+      Tool.AddParsers(SubToolMake);
+      Tool.Process.CurrentDirectory:=fWorkingDir;
+      Tool.EnvironmentOverrides:=EnvironmentOverrides;
+      Tool.Execute;
+      Tool.WaitForExit;
+      if Tool.ErrorMessage<>'' then
+        exit(mrCancel);
+    finally
+      Tool.Release(Self);
+    end;
+
+  finally
+    EnvironmentOverrides.Free;
+  end;
+end;
+
 procedure TLazarusBuilder.SpecialIdeConfig;
 var
   MakeIDECfgFilename: string;
@@ -998,6 +1082,25 @@ begin
   Result:=mrOk;
 end;
 
+function TLazarusBuilder.SearchMakeExe(Interactive: boolean): string;
+begin
+  Result:=EnvironmentOptions.GetParsedMakeFilename;
+  if (Result<>'') and (not FileExistsUTF8(Result)) then
+    Result:=FindDefaultExecutablePath(Result);
+  if (Result='') or (not FileExistsUTF8(Result)) then begin
+    Result:=FindDefaultMakePath;
+    if (Result='') or (not FileExistsUTF8(Result)) then begin
+      Result:='';
+      if not Interactive then
+        exit;
+      IDEMessageDialog(lisMakeNotFound,
+        Format(lisTheProgramMakeWasNotFoundThisToolIsNeededToBuildLa, [LineEnding]),
+        mtError, [mbCancel]);
+      exit;
+    end;
+  end;
+end;
+
 { TConfigureBuildLazarusDlg }
 
 constructor TConfigureBuildLazarusDlg.Create(TheOwner: TComponent);
diff --git a/ide/lazarus.lpi b/ide/lazarus.lpi
index 6dffcbf4b9..ed80aff64d 100644
--- a/ide/lazarus.lpi
+++ b/ide/lazarus.lpi
@@ -609,6 +609,7 @@
       <Unit>
         <Filename Value="../packager/lpkcache.pas"/>
         <IsPartOfProject Value="True"/>
+        <UnitName Value="LPKCache"/>
       </Unit>
       <Unit>
         <Filename Value="frames/editor_general_options.pas"/>
diff --git a/ide/main.pp b/ide/main.pp
index 0d4b5d3efb..b176f4cea9 100644
--- a/ide/main.pp
+++ b/ide/main.pp
@@ -7837,6 +7837,10 @@ var
   PkgCompileFlags: TPkgCompileFlags;
   OldToolStatus: TIDEToolStatus;
   CompilerKind: TPascalCompiler;
+  {$IFDEF EnableBuildIDEUsingLazbuild}
+  ErrMsg: String;
+  r: integer;
+  {$ENDIF}
 begin
   if ToolStatus<>itNone then begin
     IDEMessageDialog(lisNotNow,lisYouCanNotBuildLazarusWhileDebuggingOrCompiling,
@@ -7883,7 +7887,27 @@ begin
     end;
     MainBuildBoss.SetBuildTargetIDE;
 
-    PackageGraph.ParseBasePackages;
+    {$IFDEF EnableBuildIDEUsingLazbuild}
+    ErrMsg:=PackageGraph.SrcBasePackagesNeedLazbuild;
+    if ErrMsg<>'' then
+    begin
+      r:=IDEQuestionDialog('Major changes detected',
+        'The Lazarus sources use a different list of base packages.'+LineEnding
+        +'It is recommended to compile the IDE clean using lazbuild.',
+        mtConfirmation,[mrYes,'Clean up + lazbuild',21,'No clean up + lazbuild',mrIgnore,'Compile normally',mrCancel]);
+      case r of
+      mrYes:
+        exit(fBuilder.MakeIDEUsingLazbuild(true));
+      21:
+        exit(fBuilder.MakeIDEUsingLazbuild(false));
+      mrIgnore: ;
+      else
+        exit;
+      end;
+    end;
+    {$ELSE}
+    PackageGraph.ParseBasePackages(false);
+    {$ENDIF}
 
     // clean up
     PkgCompileFlags:=[];
diff --git a/packager/installpkgsetdlg.pas b/packager/installpkgsetdlg.pas
index e43437de59..ca010b65db 100644
--- a/packager/installpkgsetdlg.pas
+++ b/packager/installpkgsetdlg.pas
@@ -1155,7 +1155,7 @@ procedure TInstallPkgSetDialog.AddToUninstall;
     APackage:=PackageGraph.FindPackageWithID(aPackageID);
     if APackage<>nil then begin
       // check if package is a base package
-      if PackageGraph.IsStaticBasePackage(APackage.Name) then begin
+      if PackageGraph.IsCompiledInBasePackage(APackage.Name) then begin
         MessageDlg(lisUninstallImpossible,
           Format(lisThePackageCanNotBeUninstalledBecauseItIsNeededByTh, [
             APackage.Name]), mtError, [mbCancel], 0);
diff --git a/packager/lpkcache.pas b/packager/lpkcache.pas
index f9d12bf616..bd7120a93b 100644
--- a/packager/lpkcache.pas
+++ b/packager/lpkcache.pas
@@ -242,7 +242,7 @@ begin
         Info.LPKFilename:=CurFilename;
         Info.InLazSrc:=FileIsInPath(Info.LPKFilename,
                                   EnvironmentOptions.GetParsedLazarusDirectory);
-        Info.Base:=Info.InLazSrc and PackageGraph.IsStaticBasePackage(Info.ID.Name);
+        Info.Base:=Info.InLazSrc and PackageGraph.IsCompiledInBasePackage(Info.ID.Name);
         Pkg:=PackageGraph.FindPackageWithFilename(Info.LPKFilename);
         if Pkg<>nil then
           Info.Installed:=Pkg.Installed;
diff --git a/packager/packagesystem.pas b/packager/packagesystem.pas
index fd11377332..26431f4ff7 100644
--- a/packager/packagesystem.pas
+++ b/packager/packagesystem.pas
@@ -430,14 +430,15 @@ type
   public
     // installed packages
     FirstAutoInstallDependency: TPkgDependency;
-    function ParseBasePackages: boolean; // read list from current sources
+    function ParseBasePackages(Verbose: boolean): boolean; // read list from current sources
+    function SrcBasePackagesNeedLazbuild: string; // check if compiled-in and source base pkg list differ that a built using make is needed
     procedure LoadStaticBasePackages;
     procedure LoadAutoInstallPackages(PkgList: TStringList);
     procedure SortAutoInstallDependencies;
     function GetIDEInstallPackageOptions(
                  var InheritedOptionStrings: TInheritedCompOptsStrings): string;
     function SaveAutoInstallConfig: TModalResult;// for the uses section
-    function IsStaticBasePackage(PackageName: string): boolean;
+    function IsCompiledInBasePackage(PackageName: string): boolean;
     procedure FreeAutoInstallDependencies;
   public
     // registration
@@ -476,6 +477,7 @@ type
     property Verbosity: TPkgVerbosityFlags read FVerbosity write FVerbosity;
 
     // base packages
+    property SrcBasePackages: TStringListUTF8Fast read FSrcBasePackages;
     property FCLPackage: TLazPackage read FFCLPackage;
     property LCLBasePackage: TLazPackage read FLCLBasePackage;
     property LCLPackage: TLazPackage read FLCLPackage;
@@ -2123,7 +2125,7 @@ begin
   FTree.Add(APackage);
   FItems.Add(APackage);
 
-  if IsStaticBasePackage(APackage.Name) then begin
+  if IsCompiledInBasePackage(APackage.Name) then begin
     APackage.Installed:=pitStatic;
     APackage.AutoInstall:=pitStatic;
     if SysUtils.CompareText(APackage.Name,'FCL')=0 then begin
@@ -2375,7 +2377,7 @@ begin
         APackage:=TLazPackage(PkgList[i]);
         if (APackage=nil)
         or APackage.Missing
-        or IsStaticBasePackage(APackage.Name)
+        or IsCompiledInBasePackage(APackage.Name)
         or (APackage.PackageType in [lptRunTime,lptRunTimeOnly])
         then continue;
 
@@ -2398,7 +2400,7 @@ begin
                            lisPkgMangstaticPackagesConfigFile);
 end;
 
-function TLazPackageGraph.IsStaticBasePackage(PackageName: string): boolean;
+function TLazPackageGraph.IsCompiledInBasePackage(PackageName: string): boolean;
 var
   bp: TLazarusIDEBasePkg;
 begin
@@ -5119,18 +5121,34 @@ begin
   Result:=mrOk;
 end;
 
-function TLazPackageGraph.ParseBasePackages: boolean;
+function TLazPackageGraph.ParseBasePackages(Verbose: boolean): boolean;
 var
   LazDir, SrcFilename, Atom, PkgName: String;
   Code: TCodeBuffer;
   p, AtomStart: integer;
 begin
+  Result:=false;
   LazDir:=EnvironmentOptions.GetParsedLazarusDirectory;
-  if LazDir='' then exit;
+  if (LazDir='') or not FilenameIsPascalSource(LazDir) then
+  begin
+    if Verbose then
+      debugln(['Error: (lazarus) TLazPackageGraph.ParseBasePackages missing LazarusDir "',LazDir,'"']);
+    exit;
+  end;
   SrcFilename:=AppendPathDelim(LazDir)+'packager'+PathDelim+'pkgsysbasepkgs.pas';
-  if not FileExistsCached(SrcFilename) then exit;
+  if not FileExistsCached(SrcFilename) then
+  begin
+    if Verbose then
+      debugln(['Error: (lazarus) TLazPackageGraph.ParseBasePackages file not found: "',SrcFilename,'"']);
+    exit;
+  end;
   Code:=CodeToolBoss.LoadFile(SrcFilename,true,false);
-  if Code=nil then exit;
+  if Code=nil then
+  begin
+    if Verbose then
+      debugln(['Error: (lazarus) TLazPackageGraph.ParseBasePackages failed to load "',SrcFilename,'"']);
+    exit;
+  end;
   if (FSrcBasePackagesFilename=SrcFilename)
       and (FSrcBasePackagesFileChangeStep=Code.FileChangeStep) then
     exit(true); // cache valid
@@ -5140,7 +5158,11 @@ begin
   FSrcBasePackages.Clear;
 
   if SearchCodeInSource(Code.Source,'LazarusIDEBasePkgNames:',1,p,false)<1 then
+  begin
+    if Verbose then
+      debugln(['Error: (lazarus) TLazPackageGraph.ParseBasePackages failed to find LazarusIDEBasePkgNames in "',SrcFilename,'"']);
     exit;
+  end;
   AtomStart:=p;
   repeat
     Atom:=ReadNextPascalAtom(Code.Source,p,AtomStart);
@@ -5152,6 +5174,51 @@ begin
         FSrcBasePackages.Add(PkgName);
     end;
   until false;
+  Result:=true;
+end;
+
+function TLazPackageGraph.SrcBasePackagesNeedLazbuild: string;
+var
+  i: Integer;
+  PkgName, aFilename: String;
+  bp: TLazarusIDEBasePkg;
+  Pkg: TLazPackage;
+begin
+  Result:='';
+  if not ParseBasePackages(true) then
+    exit('Unable to parse base package list.');
+
+  // check if all source base packages will be installed
+  for i:=0 to FSrcBasePackages.Count-1 do
+  begin
+    PkgName:=FSrcBasePackages[i];
+    if IsCompiledInBasePackage(PkgName) then
+      continue;
+    // new base package
+    if FindDependencyByNameInList(FirstAutoInstallDependency,pddRequires,PkgName)<>nil
+    then
+      exit; // it will be installed anyway -> ok
+    // the sources need a base package, that this IDE will not install
+    // -> better use lazbuild for building
+    exit('Sources need a new base package "'+PkgName+'"');
+  end;
+
+  // check if all compiled-in base packages are also source base packages
+  for bp in TLazarusIDEBasePkg do
+  begin
+    PkgName:=LazarusIDEBasePkgNames[bp];
+    if FSrcBasePackages.IndexOf(PkgName)>=0 then continue;
+    // sources do not listen this as base package
+    Pkg:=FindPackageWithName(PkgName,nil);
+    if Pkg=nil then continue;
+    if Pkg.IsVirtual then
+      exit('Sources do not use "'+PkgName+'" as base package.'); // avoid IDE package check errors and use lazbuild
+    aFilename:=Pkg.GetResolvedFilename(true);
+    if aFilename='' then
+      exit('Sources do not use "'+PkgName+'" as base package.'); // avoid IDE package check errors and use lazbuild
+    if not FileExistsCached(aFilename) then
+      exit('Sources do not use "'+PkgName+'" as base package.'); // avoid IDE package check errors and use lazbuild
+  end;
 end;
 
 function TLazPackageGraph.PreparePackageOutputDirectory(APackage: TLazPackage;
@@ -5992,7 +6059,7 @@ begin
         // -> unable to load this dependency due to conflict
         debugln('Error: (lazarus) Open dependency found incompatible package: searched for '
                 +Dependency.AsString(true,false)+', but found '+APackage.IDAsString);
-        if IsStaticBasePackage(APackage.Name) then
+        if IsCompiledInBasePackage(APackage.Name) then
         begin
           //debugln(['Note: (lazarus) LazarusDir="',EnvironmentOptions.GetParsedLazarusDirectory,'"']);
           // wrong base package
@@ -6144,7 +6211,7 @@ begin
   OpenDependency(Dependency,false);
   if Dependency.LoadPackageResult<>lprSuccess then begin
     // a valid lpk file of the installed package can not be found
-    IsBasePkg:=IsStaticBasePackage(Dependency.PackageName);
+    IsBasePkg:=IsCompiledInBasePackage(Dependency.PackageName);
     // -> create a broken package
     BrokenPackage:=TLazPackage.CreateAndClear;
     with BrokenPackage do begin
diff --git a/packager/pkgmanager.pas b/packager/pkgmanager.pas
index 9ad5901fe0..1c5b586d15 100644
--- a/packager/pkgmanager.pas
+++ b/packager/pkgmanager.pas
@@ -1522,7 +1522,7 @@ begin
   while Dependency<>nil do begin
     if (Dependency.LoadPackageResult=lprSuccess)
     and (not Dependency.RequiredPackage.Missing)
-    and (not PackageGraph.IsStaticBasePackage(Dependency.PackageName))
+    and (not PackageGraph.IsCompiledInBasePackage(Dependency.PackageName))
     and (not (Dependency.RequiredPackage.PackageType in [lptRunTime,lptRunTimeOnly]))
     then begin
       if sl.IndexOf(Dependency.PackageName)<0 then begin
@@ -4004,7 +4004,7 @@ var
   function PkgInOldLazarusDir(APackage: TLazPackage): boolean;
   begin
     Result:=FileIsInPath(APackage.Filename,OldLazarusSrcDir)
-      or PackageGraph.IsStaticBasePackage(APackage.Name)
+      or PackageGraph.IsCompiledInBasePackage(APackage.Name)
       or (SysUtils.CompareText(copy(APackage.Filename,1,length(LazDirMacro)),LazDirMacro)=0)
   end;
 
@@ -5531,7 +5531,7 @@ begin
     PkgList:=nil;
     FPMakeList:=nil;
     try
-      PackageGraph.ParseBasePackages;
+      PackageGraph.ParseBasePackages(false);
 
       // check if package is designtime package
       if APackage.PackageType in [lptRunTime,lptRunTimeOnly] then begin
@@ -5681,7 +5681,7 @@ begin
   end;
 
   // check if package is a lazarus base package
-  if PackageGraph.IsStaticBasePackage(APackage.Name) then begin
+  if PackageGraph.IsCompiledInBasePackage(APackage.Name) then begin
     Result:=IDEMessageDialogAb(lisUninstallImpossible,
       Format(lisThePackageCanNotBeUninstalledBecauseItIsNeededByTh,[APackage.Name]),
       mtError,[mbCancel],ShowAbort);
@@ -5704,7 +5704,7 @@ begin
       if Result<>mrOk then exit;
     end;
 
-    PackageGraph.ParseBasePackages;
+    PackageGraph.ParseBasePackages(false);
 
     // remove package from auto installed packages
     if APackage.AutoInstall<>pitNope then begin
@@ -5919,7 +5919,7 @@ begin
   NewFirstAutoInstallDependency:=nil;
   PkgList:=nil;
   try
-    PackageGraph.ParseBasePackages;
+    PackageGraph.ParseBasePackages(false);
 
     if not (piiifClear in Flags) then
     begin
@@ -5991,7 +5991,7 @@ begin
       CurDependency:=PackageGraph.FirstAutoInstallDependency;
       while CurDependency<>nil do begin
         if (CurDependency.RequiredPackage<>nil)
-        and (not PackageGraph.IsStaticBasePackage(CurDependency.PackageName)) then
+        and (not PackageGraph.IsCompiledInBasePackage(CurDependency.PackageName)) then
           CurDependency.RequiredPackage.AutoInstall:=pitNope;
         CurDependency:=CurDependency.NextRequiresDependency;
       end;
@@ -6066,7 +6066,7 @@ begin
       Dependencies:=nil;
       while OldDependency<>nil do begin
         if (OldDependency.RequiredPackage<>nil)
-        and PackageGraph.IsStaticBasePackage(OldDependency.RequiredPackage.Name) then
+        and PackageGraph.IsCompiledInBasePackage(OldDependency.RequiredPackage.Name) then
         begin
           Dependency:=TPkgDependency.Create;
           Dependency.Assign(OldDependency);