diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 769003a90f959..ba2c4467703cf 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -11102,9 +11102,8 @@ Overview:
 
 The '``alloca``' instruction allocates memory on the stack frame of the
 currently executing function, to be automatically released when this
-function returns to its caller.  If the address space is not explicitly
-specified, the object is allocated in the alloca address space from the
-:ref:`datalayout string<langref_datalayout>`.
+function returns to its caller. If the address space is not explicitly
+specified, the default address space 0 is used.
 
 Arguments:
 """"""""""
@@ -11146,7 +11145,10 @@ which way the stack grows) is not specified.
 
 Note that '``alloca``' outside of the alloca address space from the
 :ref:`datalayout string<langref_datalayout>` is meaningful only if the
-target has assigned it a semantics.
+target has assigned it a semantics. For targets that specify a non-zero alloca
+address space in the :ref:`datalayout string<langref_datalayout>`, the alloca
+address space needs to be explicitly specified in the instruction if it is to be
+used.
 
 If the returned pointer is used by :ref:`llvm.lifetime.start <int_lifestart>`,
 the returned object is initially dead.