diff --git a/clang/docs/MatrixTypes.rst b/clang/docs/MatrixTypes.rst
--- a/clang/docs/MatrixTypes.rst
+++ b/clang/docs/MatrixTypes.rst
@@ -266,6 +266,18 @@
   }
 
 
+Initialization Syntax
+---------------------
+A value of a matrix type M can be initialised using aggregate initialization syntax:
+
+.. code-block:: c++
+
+  constexpr M m1 = {};
+  constexpr M m2 = {{a, b, c}, {d, e, f}};
+
+The number of constituent arrays must equal the number rows in the matrix type M and the number of elements
+in each constituent array must equal the number of columns in the matrix type.
+
 TODOs
 -----
 
@@ -274,9 +286,6 @@
 convenient. The alternative is using template deduction to extract this
 information. Also add spelling for C.
 
-Future Work: Initialization syntax.
-
-
 Decisions for the Implementation in Clang
 =========================================