diff --git a/Help/command/subdir_depends.rst b/Help/command/subdir_depends.rst
index c72a4afcf..5676c8f40 100644
--- a/Help/command/subdir_depends.rst
+++ b/Help/command/subdir_depends.rst
@@ -1,7 +1,9 @@
 subdir_depends
 --------------
 
-Deprecated.  Does nothing.
+Disallowed.  See CMake Policy :policy:`CMP0029`.
+
+Does nothing.
 
 ::
 
diff --git a/Help/manual/cmake-policies.7.rst b/Help/manual/cmake-policies.7.rst
index cb328eef8..d58fabc4c 100644
--- a/Help/manual/cmake-policies.7.rst
+++ b/Help/manual/cmake-policies.7.rst
@@ -58,3 +58,4 @@ All Policies
    /policy/CMP0026
    /policy/CMP0027
    /policy/CMP0028
+   /policy/CMP0029
diff --git a/Help/policy/CMP0029.rst b/Help/policy/CMP0029.rst
new file mode 100644
index 000000000..92ef1ec41
--- /dev/null
+++ b/Help/policy/CMP0029.rst
@@ -0,0 +1,10 @@
+CMP0029
+-------
+
+The :command:`subdir_depends` command should not be called.
+
+The implementation of this command has been empty since December 2001
+but was kept in CMake for compatibility for a long time.
+
+.. |disallowed_version| replace:: 3.0.0
+.. include:: DISALLOWED_COMMAND.txt
diff --git a/Source/cmPolicies.cxx b/Source/cmPolicies.cxx
index f7efc1e44..fcc5bfc75 100644
--- a/Source/cmPolicies.cxx
+++ b/Source/cmPolicies.cxx
@@ -246,6 +246,11 @@ cmPolicies::cmPolicies()
     CMP0028, "CMP0028",
     "Double colon in target name means ALIAS or IMPORTED target.",
     3,0,0,0, cmPolicies::WARN);
+
+  this->DefinePolicy(
+    CMP0029, "CMP0029",
+    "The subdir_depends command should not be called.",
+    3,0,0,0, cmPolicies::WARN);
 }
 
 cmPolicies::~cmPolicies()
diff --git a/Source/cmPolicies.h b/Source/cmPolicies.h
index 68cd7c227..343c01d78 100644
--- a/Source/cmPolicies.h
+++ b/Source/cmPolicies.h
@@ -80,6 +80,7 @@ public:
     CMP0027, ///< Conditionally linked imported targets with missing include
     /// directories.
     CMP0028, ///< Double colon in target name means ALIAS or IMPORTED target.
+    CMP0029, ///< Disallow command: subdir_depends
 
     /** \brief Always the last entry.
      *
diff --git a/Source/cmSubdirDependsCommand.cxx b/Source/cmSubdirDependsCommand.cxx
index 2af7bf1c9..938198300 100644
--- a/Source/cmSubdirDependsCommand.cxx
+++ b/Source/cmSubdirDependsCommand.cxx
@@ -11,10 +11,10 @@
 ============================================================================*/
 #include "cmSubdirDependsCommand.h"
 
-// cmSubdirDependsCommand
 bool cmSubdirDependsCommand::InitialPass(std::vector<std::string> const& ,
                                          cmExecutionStatus &)
 {
+  this->Disallowed(cmPolicies::CMP0029,
+    "The subdir_depends command should not be called; see CMP0029.");
   return true;
 }
-
diff --git a/Source/cmSubdirDependsCommand.h b/Source/cmSubdirDependsCommand.h
index e6f1f8fc1..f78cfb701 100644
--- a/Source/cmSubdirDependsCommand.h
+++ b/Source/cmSubdirDependsCommand.h
@@ -14,45 +14,15 @@
 
 #include "cmCommand.h"
 
-/** \class cmSubdirDependsCommand
- * \brief Legacy command.  Do not use.
- *
- * cmSubdirDependsCommand has been left in CMake for compatability with
- * projects already using it.  Its functionality in supporting parallel
- * builds is now automatic.  The command does not do anything.
- */
 class cmSubdirDependsCommand : public cmCommand
 {
 public:
-  /**
-   * This is a virtual constructor for the command.
-   */
-  virtual cmCommand* Clone()
-    {
-    return new cmSubdirDependsCommand;
-    }
-
-  /**
-   * This is called when the command is first encountered in
-   * the CMakeLists.txt file.
-   */
+  virtual cmCommand* Clone() { return new cmSubdirDependsCommand; }
   virtual bool InitialPass(std::vector<std::string> const& args,
                            cmExecutionStatus &status);
-
-  /**
-   * The name of the command as specified in CMakeList.txt.
-   */
   virtual const char* GetName() const { return "subdir_depends";}
-
-  /** This command is kept for compatibility with older CMake versions. */
-  virtual bool IsDiscouraged() const
-    {
-    return true;
-    }
-
+  virtual bool IsDiscouraged() const { return true; }
   cmTypeMacro(cmSubdirDependsCommand, cmCommand);
 };
 
-
-
 #endif
diff --git a/Tests/RunCMake/DisallowedCommands/CMP0029-NEW-result.txt b/Tests/RunCMake/DisallowedCommands/CMP0029-NEW-result.txt
new file mode 100644
index 000000000..d00491fd7
--- /dev/null
+++ b/Tests/RunCMake/DisallowedCommands/CMP0029-NEW-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/DisallowedCommands/CMP0029-NEW-stderr.txt b/Tests/RunCMake/DisallowedCommands/CMP0029-NEW-stderr.txt
new file mode 100644
index 000000000..e14708112
--- /dev/null
+++ b/Tests/RunCMake/DisallowedCommands/CMP0029-NEW-stderr.txt
@@ -0,0 +1,4 @@
+CMake Error at CMP0029-NEW.cmake:2 \(subdir_depends\):
+  The subdir_depends command should not be called; see CMP0029.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/DisallowedCommands/CMP0029-NEW.cmake b/Tests/RunCMake/DisallowedCommands/CMP0029-NEW.cmake
new file mode 100644
index 000000000..392b9d409
--- /dev/null
+++ b/Tests/RunCMake/DisallowedCommands/CMP0029-NEW.cmake
@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0029 NEW)
+subdir_depends()
diff --git a/Tests/RunCMake/DisallowedCommands/CMP0029-OLD-stderr.txt b/Tests/RunCMake/DisallowedCommands/CMP0029-OLD-stderr.txt
new file mode 100644
index 000000000..10f32932e
--- /dev/null
+++ b/Tests/RunCMake/DisallowedCommands/CMP0029-OLD-stderr.txt
@@ -0,0 +1 @@
+^$
diff --git a/Tests/RunCMake/DisallowedCommands/CMP0029-OLD.cmake b/Tests/RunCMake/DisallowedCommands/CMP0029-OLD.cmake
new file mode 100644
index 000000000..099fd90d3
--- /dev/null
+++ b/Tests/RunCMake/DisallowedCommands/CMP0029-OLD.cmake
@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0029 OLD)
+subdir_depends()
diff --git a/Tests/RunCMake/DisallowedCommands/CMP0029-WARN-stderr.txt b/Tests/RunCMake/DisallowedCommands/CMP0029-WARN-stderr.txt
new file mode 100644
index 000000000..32a452a74
--- /dev/null
+++ b/Tests/RunCMake/DisallowedCommands/CMP0029-WARN-stderr.txt
@@ -0,0 +1,7 @@
+CMake Warning \(dev\) at CMP0029-WARN.cmake:1 \(subdir_depends\):
+  Policy CMP0029 is not set: The subdir_depends command should not be called.
+  Run "cmake --help-policy CMP0029" for policy details.  Use the cmake_policy
+  command to set the policy and suppress this warning.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.
diff --git a/Tests/RunCMake/DisallowedCommands/CMP0029-WARN.cmake b/Tests/RunCMake/DisallowedCommands/CMP0029-WARN.cmake
new file mode 100644
index 000000000..1ceb1f85e
--- /dev/null
+++ b/Tests/RunCMake/DisallowedCommands/CMP0029-WARN.cmake
@@ -0,0 +1 @@
+subdir_depends()
diff --git a/Tests/RunCMake/DisallowedCommands/RunCMakeTest.cmake b/Tests/RunCMake/DisallowedCommands/RunCMakeTest.cmake
index 5f26857c5..50911ac7c 100644
--- a/Tests/RunCMake/DisallowedCommands/RunCMakeTest.cmake
+++ b/Tests/RunCMake/DisallowedCommands/RunCMakeTest.cmake
@@ -1,6 +1,7 @@
 include(RunCMake)
 
 foreach(p
+    CMP0029
     )
   run_cmake(${p}-WARN)
   run_cmake(${p}-OLD)