diff --git a/src/core/pal/pal.cpp b/src/core/pal/pal.cpp
index bfc04433d57..d429940b574 100644
--- a/src/core/pal/pal.cpp
+++ b/src/core/pal/pal.cpp
@@ -455,7 +455,7 @@ std::unique_ptr<Problem> Pal::extractProblem( const QgsRectangle &extent, const
   return extract( extent, mapBoundary );
 }
 
-QList<LabelPosition *> Pal::solveProblem( Problem *prob, bool displayAll )
+QList<LabelPosition *> Pal::solveProblem( Problem *prob, bool displayAll, QList<LabelPosition *> *unlabeled )
 {
   if ( !prob )
     return QList<LabelPosition *>();
@@ -476,7 +476,7 @@ QList<LabelPosition *> Pal::solveProblem( Problem *prob, bool displayAll )
     return QList<LabelPosition *>();
   }
 
-  return prob->getSolution( displayAll );
+  return prob->getSolution( displayAll, unlabeled );
 }
 
 
diff --git a/src/core/pal/pal.h b/src/core/pal/pal.h
index 1e8cf8778fb..6d5ff4419ed 100644
--- a/src/core/pal/pal.h
+++ b/src/core/pal/pal.h
@@ -143,7 +143,19 @@ namespace pal
        */
       std::unique_ptr< Problem > extractProblem( const QgsRectangle &extent, const QgsGeometry &mapBoundary );
 
-      QList<LabelPosition *> solveProblem( Problem *prob, bool displayAll );
+      /**
+       * Solves the labeling problem, selecting the best candidate locations for all labels and returns a list of these
+       * calculated label positions.
+       *
+       * If \a displayAll is true, then the best positions for ALL labels will be returned, regardless of whether these
+       * labels overlap other labels.
+       *
+       * If the optional \a unlabeled list is specified, it will be filled with a list of all feature labels which could
+       * not be placed in the returned solution (e.g. due to overlaps or other constraints).
+       *
+       * Ownership of the returned labels is not transferred - it resides with the pal object.
+       */
+      QList<LabelPosition *> solveProblem( Problem *prob, bool displayAll, QList<pal::LabelPosition *> *unlabeled = nullptr );
 
       /**
        *\brief Set flag show partial label
diff --git a/src/core/pal/problem.cpp b/src/core/pal/problem.cpp
index ae298b77958..6df4fae696f 100644
--- a/src/core/pal/problem.cpp
+++ b/src/core/pal/problem.cpp
@@ -2216,7 +2216,7 @@ bool Problem::compareLabelArea( pal::LabelPosition *l1, pal::LabelPosition *l2 )
   return l1->getWidth() * l1->getHeight() > l2->getWidth() * l2->getHeight();
 }
 
-QList<LabelPosition *> Problem::getSolution( bool returnInactive )
+QList<LabelPosition *> Problem::getSolution( bool returnInactive, QList<LabelPosition *> *unlabeled )
 {
   int i;
   QList<LabelPosition *> solList;
@@ -2238,6 +2238,10 @@ QList<LabelPosition *> Problem::getSolution( bool returnInactive )
     {
       solList.push_back( mLabelPositions.at( featStartId[i] ) ); // unplaced label
     }
+    else if ( unlabeled )
+    {
+      unlabeled->push_back( mLabelPositions.at( featStartId[i] ) );
+    }
   }
 
   // if features collide, order by size, so smaller ones appear on top
diff --git a/src/core/pal/problem.h b/src/core/pal/problem.h
index 2506da46372..361a92aaeb1 100644
--- a/src/core/pal/problem.h
+++ b/src/core/pal/problem.h
@@ -150,7 +150,19 @@ namespace pal
        */
       void chain_search();
 
-      QList<LabelPosition *> getSolution( bool returnInactive );
+      /**
+       * Solves the labeling problem, selecting the best candidate locations for all labels and returns a list of these
+       * calculated label positions.
+       *
+       * If \a returnInactive is true, then the best positions for ALL labels will be returned, regardless of whether these
+       * labels overlap other labels.
+       *
+       * If the optional \a unlabeled list is specified, it will be filled with a list of all feature labels which could
+       * not be placed in the returned solution (e.g. due to overlaps or other constraints).
+       *
+       * Ownership of the returned labels is not transferred - it resides with the pal object.
+       */
+      QList<LabelPosition *> getSolution( bool returnInactive, QList<LabelPosition *> *unlabeled = nullptr );
 
       PalStat *getStats();