diff --git a/doc/api_break.dox b/doc/api_break.dox
index 44cea05706d..529b0280c4d 100644
--- a/doc/api_break.dox
+++ b/doc/api_break.dox
@@ -1233,6 +1233,7 @@ empty geometry collection)
 - smoothLine and smoothPolygon are no longer public API (use smooth() instead)
 - avoidIntersections() got an extra argument: list of layers to include in the operation (previously read from active QgsProject)
 - isGeosEmpty() was removed. Use isEmpty() instead.
+- reshapeGeometry() expects QgsLineString as a parameter instead of a list of 2D points (so that it can support 3D geometries)
 
 
 QgsGeometryAnalyzer        {#qgis_api_break_3_0_QgsGeometryAnalyzer}
diff --git a/python/core/geometry/qgsgeometry.sip b/python/core/geometry/qgsgeometry.sip
index fca0129237e..434d7d6f322 100644
--- a/python/core/geometry/qgsgeometry.sip
+++ b/python/core/geometry/qgsgeometry.sip
@@ -488,7 +488,7 @@ not disjoint with existing polygons of the feature
  :rtype: int
 %End
 
-    int reshapeGeometry( const QList<QgsPointXY> &reshapeWithLine );
+    int reshapeGeometry( const QgsLineString &reshapeLineString );
 %Docstring
  Replaces a part of this geometry with another line
  :return: 0 in case of success
diff --git a/python/core/geometry/qgslinestring.sip b/python/core/geometry/qgslinestring.sip
index 47d5a0cad68..84f31d31e18 100644
--- a/python/core/geometry/qgslinestring.sip
+++ b/python/core/geometry/qgslinestring.sip
@@ -26,6 +26,12 @@ class QgsLineString: QgsCurve
   public:
     QgsLineString();
 
+    QgsLineString( const QVector<QgsPoint> &points );
+%Docstring
+ Construct a linestring from a vector of points.
+.. versionadded:: 3.0
+%End
+
     QgsLineString( const QVector<double> &x, const QVector<double> &y,
                    const QVector<double> &z = QVector<double>(),
                    const QVector<double> &m = QVector<double>() );
diff --git a/src/app/qgsmaptoolreshape.cpp b/src/app/qgsmaptoolreshape.cpp
index 3600cb63784..392e651edeb 100644
--- a/src/app/qgsmaptoolreshape.cpp
+++ b/src/app/qgsmaptoolreshape.cpp
@@ -16,6 +16,7 @@
 #include "qgsmaptoolreshape.h"
 #include "qgsfeatureiterator.h"
 #include "qgsgeometry.h"
+#include "qgslinestring.h"
 #include "qgsmapcanvas.h"
 #include "qgsproject.h"
 #include "qgsvectorlayer.h"
@@ -84,6 +85,10 @@ void QgsMapToolReshape::cadCanvasReleaseEvent( QgsMapMouseEvent *e )
       bbox.combineExtentWith( points().at( i ).x(), points().at( i ).y() );
     }
 
+    QgsLineString reshapeLineString( points() );
+    if ( QgsWkbTypes::hasZ( vlayer->wkbType() ) )
+      reshapeLineString.addZValue( defaultZValue() );
+
     //query all the features that intersect bounding box of capture line
     QgsFeatureIterator fit = vlayer->getFeatures( QgsFeatureRequest().setFilterRect( bbox ).setSubsetOfAttributes( QgsAttributeList() ) );
     QgsFeature f;
@@ -99,7 +104,7 @@ void QgsMapToolReshape::cadCanvasReleaseEvent( QgsMapMouseEvent *e )
       QgsGeometry geom = f.geometry();
       if ( !geom.isNull() )
       {
-        reshapeReturn = geom.reshapeGeometry( points() );
+        reshapeReturn = geom.reshapeGeometry( reshapeLineString );
         if ( reshapeReturn == 0 )
         {
           //avoid intersections on polygon layers
diff --git a/src/core/geometry/qgsgeometry.cpp b/src/core/geometry/qgsgeometry.cpp
index 38e975e3a24..9e710d50c70 100644
--- a/src/core/geometry/qgsgeometry.cpp
+++ b/src/core/geometry/qgsgeometry.cpp
@@ -816,15 +816,13 @@ int QgsGeometry::splitGeometry( const QList<QgsPointXY> &splitLine, QList<QgsGeo
   return result;
 }
 
-int QgsGeometry::reshapeGeometry( const QList<QgsPointXY> &reshapeWithLine )
+int QgsGeometry::reshapeGeometry( const QgsLineString &reshapeLineString )
 {
   if ( !d->geometry )
   {
     return 0;
   }
 
-  QgsLineString reshapeLineString( reshapeWithLine );
-
   QgsGeos geos( d->geometry );
   int errorCode = 0;
   QgsAbstractGeometry *geom = geos.reshapeGeometry( reshapeLineString, &errorCode );
diff --git a/src/core/geometry/qgsgeometry.h b/src/core/geometry/qgsgeometry.h
index e130f77e2ea..20d54162071 100644
--- a/src/core/geometry/qgsgeometry.h
+++ b/src/core/geometry/qgsgeometry.h
@@ -491,7 +491,7 @@ class CORE_EXPORT QgsGeometry
      * \returns 0 in case of success
      * \since QGIS 1.3
      */
-    int reshapeGeometry( const QList<QgsPointXY> &reshapeWithLine );
+    int reshapeGeometry( const QgsLineString &reshapeLineString );
 
     /** Changes this geometry such that it does not intersect the other geometry
      * \param other geometry that should not be intersect
diff --git a/src/core/geometry/qgslinestring.cpp b/src/core/geometry/qgslinestring.cpp
index 94b00d32b9b..212a4a423fe 100644
--- a/src/core/geometry/qgslinestring.cpp
+++ b/src/core/geometry/qgslinestring.cpp
@@ -40,6 +40,43 @@ QgsLineString::QgsLineString(): QgsCurve()
   mWkbType = QgsWkbTypes::LineString;
 }
 
+QgsLineString::QgsLineString( const QVector<QgsPoint> &points )
+{
+  if ( points.isEmpty() )
+  {
+    mWkbType = QgsWkbTypes::LineString;
+    return;
+  }
+  QgsWkbTypes::Type ptType = points.at( 0 ).wkbType();
+  mWkbType = QgsWkbTypes::zmType( QgsWkbTypes::LineString, QgsWkbTypes::hasZ( ptType ), QgsWkbTypes::hasM( ptType ) );
+  mX.resize( points.count() );
+  mY.resize( points.count() );
+  double *x = mX.data();
+  double *y = mY.data();
+  double *z = nullptr;
+  double *m = nullptr;
+  if ( QgsWkbTypes::hasZ( mWkbType ) )
+  {
+    mZ.resize( points.count() );
+    z = mZ.data();
+  }
+  if ( QgsWkbTypes::hasM( mWkbType ) )
+  {
+    mM.resize( points.count() );
+    m = mM.data();
+  }
+
+  Q_FOREACH ( const QgsPoint &pt, points )
+  {
+    *x++ = pt.x();
+    *y++ = pt.y();
+    if ( z )
+      *z++ = pt.z();
+    if ( m )
+      *m++ = pt.m();
+  }
+}
+
 QgsLineString::QgsLineString( const QVector<double> &x, const QVector<double> &y, const QVector<double> &z, const QVector<double> &m )
 {
   mWkbType = QgsWkbTypes::LineString;
diff --git a/src/core/geometry/qgslinestring.h b/src/core/geometry/qgslinestring.h
index 95231d5b90c..6e28c22479f 100644
--- a/src/core/geometry/qgslinestring.h
+++ b/src/core/geometry/qgslinestring.h
@@ -42,6 +42,12 @@ class CORE_EXPORT QgsLineString: public QgsCurve
   public:
     QgsLineString();
 
+    /**
+     * Construct a linestring from a vector of points.
+     * \since QGIS 3.0
+     */
+    QgsLineString( const QVector<QgsPoint> &points );
+
     /**
      * Construct a linestring from arrays of coordinates. If the z or m
      * arrays are non-empty then the resultant linestring will have
diff --git a/tests/src/core/testqgsgeometry.cpp b/tests/src/core/testqgsgeometry.cpp
index d4ec73606b5..97d52eedbdb 100644
--- a/tests/src/core/testqgsgeometry.cpp
+++ b/tests/src/core/testqgsgeometry.cpp
@@ -126,6 +126,8 @@ class TestQgsGeometry : public QObject
 
     void isSimple();
 
+    void reshapeGeometryLineMerge();
+
   private:
     //! A helper method to do a render check to see if the geometry op is as expected
     bool renderCheck( const QString &testName, const QString &comment = QLatin1String( QLatin1String( "" ) ), int mismatchCount = 0 );
@@ -1078,7 +1080,27 @@ void TestQgsGeometry::lineString()
   QCOMPARE( fromPts.xAt( 2 ), 21.0 );
   QCOMPARE( fromPts.yAt( 2 ), 22.0 );
 
-
+  // from QVector<QgsPoint>
+  QVector<QgsPoint> ptsVector;
+  ptsVector << QgsPoint( 10, 20 ) << QgsPoint( 30, 40 );
+  QgsLineString fromVector( ptsVector );
+  QCOMPARE( fromVector.wkbType(), QgsWkbTypes::LineString );
+  QCOMPARE( fromVector.numPoints(), 2 );
+  QCOMPARE( fromVector.xAt( 0 ), 10.0 );
+  QCOMPARE( fromVector.yAt( 0 ), 20.0 );
+  QCOMPARE( fromVector.xAt( 1 ), 30.0 );
+  QCOMPARE( fromVector.yAt( 1 ), 40.0 );
+  QVector<QgsPoint> ptsVector3D;
+  ptsVector3D << QgsPoint( QgsWkbTypes::PointZ, 10, 20, 100 ) << QgsPoint( QgsWkbTypes::PointZ, 30, 40, 200 );
+  QgsLineString fromVector3D( ptsVector3D );
+  QCOMPARE( fromVector3D.wkbType(), QgsWkbTypes::LineStringZ );
+  QCOMPARE( fromVector3D.numPoints(), 2 );
+  QCOMPARE( fromVector3D.xAt( 0 ), 10.0 );
+  QCOMPARE( fromVector3D.yAt( 0 ), 20.0 );
+  QCOMPARE( fromVector3D.zAt( 0 ), 100.0 );
+  QCOMPARE( fromVector3D.xAt( 1 ), 30.0 );
+  QCOMPARE( fromVector3D.yAt( 1 ), 40.0 );
+  QCOMPARE( fromVector3D.zAt( 1 ), 200.0 );
 
   //addVertex
   QgsLineString l2;
@@ -5452,5 +5474,48 @@ void TestQgsGeometry::isSimple()
   }
 }
 
+void TestQgsGeometry::reshapeGeometryLineMerge()
+{
+  int res;
+  QgsGeometry g2D = QgsGeometry::fromWkt( "LINESTRING(10 10, 20 20)" );
+  QgsGeometry g3D = QgsGeometry::fromWkt( "LINESTRINGZ(10 10 1, 20 20 2)" );
+
+  // prepare 2D reshaping line
+  QVector<QgsPoint> v2D_1, v2D_2;
+  v2D_1 << QgsPoint( 20, 20 ) << QgsPoint( 30, 30 );
+  v2D_2 << QgsPoint( 10, 10 ) << QgsPoint( -10, -10 );
+  QgsLineString line2D_1( v2D_1 ), line2D_2( v2D_2 );
+
+  // prepare 3D reshaping line
+  QVector<QgsPoint> v3D_1, v3D_2;
+  v3D_1 << QgsPoint( QgsWkbTypes::PointZ, 20, 20, 2 ) << QgsPoint( QgsWkbTypes::PointZ, 30, 30, 3 );
+  v3D_2 << QgsPoint( QgsWkbTypes::PointZ, 10, 10, 1 ) << QgsPoint( QgsWkbTypes::PointZ, -10, -10, -1 );
+  QgsLineString line3D_1( v3D_1 ), line3D_2( v3D_2 );
+
+  // append with 2D line
+  QgsGeometry g2D_1 = g2D;
+  res = g2D_1.reshapeGeometry( line2D_1 );
+  QCOMPARE( res, 0 );
+  QCOMPARE( g2D_1.exportToWkt(), QString( "LineString (10 10, 20 20, 30 30)" ) );
+
+  // prepend with 2D line
+  QgsGeometry g2D_2 = g2D;
+  res = g2D_2.reshapeGeometry( line2D_2 );
+  QCOMPARE( res, 0 );
+  QCOMPARE( g2D_2.exportToWkt(), QString( "LineString (-10 -10, 10 10, 20 20)" ) );
+
+  // append with 3D line
+  QgsGeometry g3D_1 = g3D;
+  res = g3D_1.reshapeGeometry( line3D_1 );
+  QCOMPARE( res, 0 );
+  QCOMPARE( g3D_1.exportToWkt(), QString( "LineStringZ (10 10 1, 20 20 2, 30 30 3)" ) );
+
+  // prepend with 3D line
+  QgsGeometry g3D_2 = g3D;
+  res = g3D_2.reshapeGeometry( line3D_2 );
+  QCOMPARE( res, 0 );
+  QCOMPARE( g3D_2.exportToWkt(), QString( "LineStringZ (-10 -10 -1, 10 10 1, 20 20 2)" ) );
+}
+
 QGSTEST_MAIN( TestQgsGeometry )
 #include "testqgsgeometry.moc"