matplotlib · alexhartl · Dec 22, 2019 · Dec 22, 2019 · Dec 22, 2019 · Dec 22, 2019
diff --git a/doc/api/axes_api.rst b/doc/api/axes_api.rst
@@ -307,6 +307,8 @@ Axis Labels, title, and legend
    Axes.get_xlabel
    Axes.set_ylabel
    Axes.get_ylabel
+   Axes.set_xlabel_legend
+   Axes.set_ylabel_legend
 
    Axes.set_title
    Axes.get_title

diff --git a/doc/users/next_whats_new/2019-12-22-axis-label-legend.rst b/doc/users/next_whats_new/2019-12-22-axis-label-legend.rst
@@ -0,0 +1,7 @@
+Support for axis label legends
+------------------------------
+
+Legends can now be placed next to axis labels, enabling more
+space-efficient and intuitive ``twinx()`` plots. Such legends are created
+using ``plt.xlabel_legend()`` and ``plt.ylabel_legend()``, which each
+accept one artist handle as understood by ``plt.legend()``.
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -214,6 +214,21 @@ def set_xlabel(self, xlabel, fontdict=None, labelpad=None, **kwargs):
             self.xaxis.labelpad = labelpad
         return self.xaxis.set_label_text(xlabel, fontdict, **kwargs)
 
+    def set_xlabel_legend(self, handle, **kwargs):
+        """
+        Place a legend next to the axis label.
+
+        Parameters
+        ----------
+        handle: `.Artist`
+            An artist (e.g. lines, patches) to be shown as legend.
+
+        **kwargs: `.LegendConfig` properties
+            Additional properties to control legend appearance.
+        """
+        label = self.xaxis.get_label()
+        label.set_legend_handle(handle, **kwargs)
+
     def get_ylabel(self):
         """
         Get the ylabel text string.
@@ -248,6 +263,36 @@ def set_ylabel(self, ylabel, fontdict=None, labelpad=None, **kwargs):
             self.yaxis.labelpad = labelpad
         return self.yaxis.set_label_text(ylabel, fontdict, **kwargs)
 
+    def set_ylabel_legend(self, handle, **kwargs):
+        """
+        Place a legend next to the axis label.
+
+        Parameters
+        ----------
+        handle: `.Artist`
+            An artist (e.g. lines, patches) to be shown as legend.
+
+        **kwargs: `.LegendConfig` properties
+            Additional properties to control legend appearance.
+
+        Examples
+        --------
+        Plot two lines on different axes with legends placed next to the
+        axis labels::
+
+            artist, = plt.plot([0, 1, 2], [0, 1, 2], "b-")
+            plt.ylabel('Density')
+            plt.ylabel_legend(artist)
+
+            plt.twinx()
+            artist, = plt.plot([0, 1, 2], [0, 3, 2], "r-")
+            plt.ylabel('Temperature')
+            plt.ylabel_legend(artist)
+            plt.show()
+        """
+        label = self.yaxis.get_label()
+        label.set_legend_handle(handle, **kwargs)
+
     def get_legend_handles_labels(self, legend_handler_map=None):
         """
         Return handles and labels for legend

diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
@@ -11,6 +11,7 @@
 import matplotlib.artist as martist
 import matplotlib.cbook as cbook
 import matplotlib.font_manager as font_manager
+import matplotlib.legend as mlegend
 import matplotlib.lines as mlines
 import matplotlib.scale as mscale
 import matplotlib.text as mtext
@@ -691,7 +692,7 @@ def __init__(self, axes, pickradius=15):
         self._autolabelpos = True
         self._smart_bounds = False  # Deprecated in 3.2
 
-        self.label = mtext.Text(
+        self.label = mlegend.TextWithLegend(
             np.nan, np.nan,
             fontproperties=font_manager.FontProperties(
                 size=rcParams['axes.labelsize'],