diff --git a/resource/planner/c++/planner.cpp b/resource/planner/c++/planner.cpp
index 0f55c0dc5..94dadbf62 100644
--- a/resource/planner/c++/planner.cpp
+++ b/resource/planner/c++/planner.cpp
@@ -229,6 +229,26 @@ int planner::restore_track_points ()
     return rc;
 }
 
+int planner::update (uint64_t resource_total)
+{
+    int64_t delta = resource_total - m_total_resources;
+    m_total_resources = static_cast<int64_t> (resource_total);
+    scheduled_point_t *point = nullptr;
+    if (delta == 0)
+        return 0;
+    point = m_sched_point_tree.get_state (m_plan_start);
+    while (point) {
+        // Allow remaining to be negative. This should only happen for
+        // reservations, which will be removed and rescheduled during the
+        // next cycle. Planner C interface checks should catch negative
+        // remaining while adding spans. Return code is int rather than
+        // void as we may need checks in the future.
+        point->remaining = point->remaining + delta;
+        point = m_sched_point_tree.next (point);
+    }
+    return 0;
+}
+
 int64_t planner::get_total_resources () const
 {
     return m_total_resources;
diff --git a/resource/planner/c++/planner.hpp b/resource/planner/c++/planner.hpp
index 05fc39f75..4499eadf2 100644
--- a/resource/planner/c++/planner.hpp
+++ b/resource/planner/c++/planner.hpp
@@ -51,6 +51,7 @@ class planner {
     int erase ();
     int reinitialize (int64_t base_time, uint64_t duration);
     int restore_track_points ();
+    int update (uint64_t resource_total);
     
     // Resources and duration
     int64_t get_total_resources () const;
diff --git a/resource/planner/c/planner.h b/resource/planner/c/planner.h
index 0f777973f..25cf66876 100644
--- a/resource/planner/c/planner.h
+++ b/resource/planner/c/planner.h
@@ -229,6 +229,21 @@ int64_t planner_span_resource_count (planner_t *ctx, int64_t span_id);
 */
 bool planners_equal (planner_t *lhs, planner_t *rhs);
 
+/*! Update the counts and resource types to support elasticity.
+ *
+ *  \param resource_total
+ *                      64-bit unsigned integer of
+ *                      the total count of available resources
+ *                      of the resource type.
+ *  \param resource_type
+ *                      string containing
+ *                      the planner resource type.
+ *  \return             0 on success; -1 on an error with errno set as follows:
+ *                          EINVAL: invalid argument.
+ */
+int planner_update (planner_t *ctx,
+                    uint64_t resource_total);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/resource/planner/c/planner_c_interface.cpp b/resource/planner/c/planner_c_interface.cpp
index e0f154f9c..ff65fc5b3 100644
--- a/resource/planner/c/planner_c_interface.cpp
+++ b/resource/planner/c/planner_c_interface.cpp
@@ -698,6 +698,12 @@ extern "C" bool planners_equal (planner_t *lhs, planner_t *rhs)
     return (*(lhs->plan) == *(rhs->plan));
 }
 
+extern "C" int planner_update (planner_t *ctx,
+                               uint64_t resource_total)
+{
+    return ctx->plan->update (resource_total);
+}
+
 /*
  * vi: ts=4 sw=4 expandtab
  */