diff --git a/src/aig/gia/giaDup.c b/src/aig/gia/giaDup.c
index 2b4a0199f..ed0e682f4 100644
--- a/src/aig/gia/giaDup.c
+++ b/src/aig/gia/giaDup.c
@@ -6163,6 +6163,62 @@ Gia_Man_t * Gia_ManDupCofs( Gia_Man_t * p, Vec_Int_t * vVarNums )
     Gia_ManStop( pTemp );  
     return pNew;    
 }
+Gia_Man_t * Gia_ManDupUnCofs( Gia_Man_t * p, Vec_Int_t * vVarNums )
+{
+    Gia_Man_t * pNew, * pTemp; Gia_Obj_t * pObj;
+    Vec_Int_t * vOutLits, * vVarLits, * vTemp;
+    int i, v, g, nVars = Vec_IntSize(vVarNums);
+    int nMints = 1 << nVars;
+    int nOrigCos;
+    assert( Gia_ManRegNum(p) == 0 );
+    assert( nMints > 0 );
+    assert( Gia_ManCoNum(p) % nMints == 0 );
+    nOrigCos = Gia_ManCoNum(p) / nMints;
+    vVarLits = Vec_IntStartFull( nVars );
+    pNew = Gia_ManStart( Gia_ManObjNum(p) + Gia_ManCoNum(p) );
+    pNew->pName = Abc_UtilStrsav( p->pName );
+    Gia_ManFillValue( p );
+    Gia_ManConst0(p)->Value = 0;
+    Gia_ManForEachCi( p, pObj, i )
+    {
+        pObj->Value = Gia_ManAppendCi( pNew );
+        if ( (v = Vec_IntFind( vVarNums, i )) >= 0 )
+            Vec_IntWriteEntry( vVarLits, v, pObj->Value );
+    }
+    Vec_IntForEachEntry( vVarLits, g, i )
+        assert( g >= 0 );
+    Gia_ManHashAlloc( pNew );
+    Gia_ManForEachAnd( p, pObj, i )
+        pObj->Value = Gia_ManHashAnd( pNew, Gia_ObjFanin0Copy(pObj), Gia_ObjFanin1Copy(pObj) );
+    vOutLits = Vec_IntAlloc( Gia_ManCoNum(p) );
+    Gia_ManForEachCo( p, pObj, i )
+        Vec_IntPush( vOutLits, Gia_ObjFanin0Copy(pObj) );
+    vTemp = Vec_IntAlloc( nMints );
+    for ( i = 0; i < nOrigCos; i++ )
+    {
+        Vec_IntFill( vTemp, nMints, 0 );
+        for ( g = 0; g < nMints; g++ )
+            Vec_IntWriteEntry( vTemp, g, Vec_IntEntry(vOutLits, g * nOrigCos + i) );
+        for ( v = 0; v < nVars; v++ )
+        {
+            int Stride = 1 << v;
+            for ( g = 0; g < nMints; g += 2 * Stride )
+            {
+                int iLit0 = Vec_IntEntry( vTemp, g );
+                int iLit1 = Vec_IntEntry( vTemp, g + Stride );
+                int iLitR = Gia_ManHashMux( pNew, Vec_IntEntry( vVarLits, v ), iLit1, iLit0 );
+                Vec_IntWriteEntry( vTemp, g, iLitR );
+            }
+        }
+        Gia_ManAppendCo( pNew, Vec_IntEntry( vTemp, 0 ) );
+    }
+    Vec_IntFree( vTemp );
+    Vec_IntFree( vOutLits );
+    Vec_IntFree( vVarLits );
+    pNew = Gia_ManCleanup( pTemp = pNew );
+    Gia_ManStop( pTemp );  
+    return pNew;    
+}
 
 /**Function*************************************************************
 
@@ -6673,4 +6729,3 @@ Gia_Man_t * Gia_ManDupExtractMffc( Gia_Man_t * p, Vec_Int_t * vLits, Vec_Int_t *
 
 
 ABC_NAMESPACE_IMPL_END
-
diff --git a/src/base/abci/abc.c b/src/base/abci/abc.c
index 33323687f..24994dbab 100644
--- a/src/base/abci/abc.c
+++ b/src/base/abci/abc.c
@@ -36623,10 +36623,11 @@ usage:
 int Abc_CommandAbc9Cofs( Abc_Frame_t * pAbc, int argc, char ** argv )
 {
     extern Gia_Man_t * Gia_ManDupCofs( Gia_Man_t * p, Vec_Int_t * vVarNums );
+    extern Gia_Man_t * Gia_ManDupUnCofs( Gia_Man_t * p, Vec_Int_t * vVarNums );
     Gia_Man_t * pTemp;  Vec_Int_t * vVars = NULL;
-    int c, iVar = 0, nVars = 0, fVerbose = 0;
+    int c, iVar = 0, nVars = 0, fLastVars = 0, fVerbose = 0, fUndo = 0;
     Extra_UtilGetoptReset();
-    while ( ( c = Extra_UtilGetopt( argc, argv, "VNvh" ) ) != EOF )
+    while ( ( c = Extra_UtilGetopt( argc, argv, "VNluvh" ) ) != EOF )
     {
         switch ( c )
         {
@@ -36652,6 +36653,12 @@ int Abc_CommandAbc9Cofs( Abc_Frame_t * pAbc, int argc, char ** argv )
             if ( nVars < 0 )
                 goto usage;
             break;
+        case 'l':
+            fLastVars ^= 1;
+            break;
+        case 'u':
+            fUndo ^= 1;
+            break;
         case 'v':
             fVerbose ^= 1;
             break;
@@ -36672,8 +36679,14 @@ int Abc_CommandAbc9Cofs( Abc_Frame_t * pAbc, int argc, char ** argv )
         Vec_IntPush( vVars, iVar );
     }
     else if ( nVars ) {
-        Abc_Print( 0, "Cofactoring the first %d inputs.\n", nVars );
-        vVars = Vec_IntStartNatural( nVars );
+        Abc_Print( 0, "Cofactoring the %s %d inputs.\n", fLastVars ? "last":"first", nVars );
+        if ( fLastVars) {
+            vVars = Vec_IntAlloc(nVars);
+            for ( int v = 0; v < nVars; v++ )
+                Vec_IntPush( vVars, Gia_ManCiNum(pAbc->pGia)-nVars+v );
+        }
+        else
+            vVars = Vec_IntStartNatural( nVars );
     }
     else if ( globalUtilOptind < argc ) {
         vVars = Vec_IntAlloc( argc );
@@ -36684,16 +36697,18 @@ int Abc_CommandAbc9Cofs( Abc_Frame_t * pAbc, int argc, char ** argv )
         Abc_Print( -1, "One of the parameters, -V <num> or -L <num>, should be set on the command line.\n" );
         goto usage;
     }
-    pTemp = Gia_ManDupCofs( pAbc->pGia, vVars );
+    pTemp = fUndo ? Gia_ManDupUnCofs( pAbc->pGia, vVars ) : Gia_ManDupCofs( pAbc->pGia, vVars );
     Abc_FrameUpdateGia( pAbc, pTemp );
     Vec_IntFree( vVars );
     return 0;
 
 usage:
-    Abc_Print( -2, "usage: &cofs [-VN num] [-vh]\n" );
-    Abc_Print( -2, "\t         derives cofactors w.r.t the set of variables\n" );
+    Abc_Print( -2, "usage: &cofs [-VN num] [-luvh]\n" );
+    Abc_Print( -2, "\t         derives cofactors or reconstructs them w.r.t the set of variables\n" );
     Abc_Print( -2, "\t-V num : the zero-based ID of one variable to cofactor [default = %d]\n", iVar );
     Abc_Print( -2, "\t-N num : cofactoring the given number of first input variables [default = %d]\n", nVars );
+    Abc_Print( -2, "\t-l     : toggle cofactoring last variables instead [default = %s]\n", fLastVars? "yes": "no" );
+    Abc_Print( -2, "\t-u     : undo cofactoring (recombine cofactors using muxes) [default = %s]\n", fUndo? "yes": "no" );
     Abc_Print( -2, "\t-v     : toggle printing verbose information [default = %s]\n", fVerbose? "yes": "no" );
     Abc_Print( -2, "\t-h     : print the command usage\n");
     return 1;