diff --git a/CIME/XML/env_batch.py b/CIME/XML/env_batch.py
index 580a8e9d434..aea6342b457 100644
--- a/CIME/XML/env_batch.py
+++ b/CIME/XML/env_batch.py
@@ -223,12 +223,35 @@ def get_job_overrides(self, job, case):
             overrides["tasks_per_node"] = tasks_per_node
             if thread_count:
                 overrides["thread_count"] = thread_count
+                total_tasks = total_tasks * thread_count
+            else:
+                total_tasks = total_tasks * case.thread_count
         else:
-            total_tasks = case.get_value("TOTALPES") * int(case.thread_count)
+            # Total PES accounts for threads as well as mpi tasks
+            total_tasks = case.get_value("TOTALPES")
             thread_count = case.thread_count
-        if int(total_tasks) * int(thread_count) < case.get_value("MAX_TASKS_PER_NODE"):
+        if int(total_tasks) < case.get_value("MAX_TASKS_PER_NODE"):
             overrides["max_tasks_per_node"] = int(total_tasks)
 
+        # when developed this variable was only needed on derecho, but I have tried to
+        # make it general enough that it can be used on other systems by defining MEM_PER_TASK and MAX_MEM_PER_NODE in config_machines.xml
+        # and adding {{ mem_per_node }} in config_batch.xml
+        try:
+            mem_per_task = case.get_value("MEM_PER_TASK")
+            max_mem_per_node = case.get_value("MAX_MEM_PER_NODE")
+            mem_per_node = total_tasks
+
+            if mem_per_node < mem_per_task:
+                mem_per_node = mem_per_task
+            elif mem_per_node > max_mem_per_node:
+                mem_per_node = max_mem_per_node
+            overrides["mem_per_node"] = mem_per_node
+        except TypeError:
+            # ignore this, the variables are not defined for this machine
+            pass
+        except Exception as error:
+            print("An exception occured:", error)
+
         overrides["ngpus_per_node"] = ngpus_per_node
         overrides["mpirun"] = case.get_mpirun_cmd(job=job, overrides=overrides)
         return overrides
diff --git a/CIME/data/config/xml_schemas/config_machines.xsd b/CIME/data/config/xml_schemas/config_machines.xsd
index 6be3efd952e..d6cbe51f1ec 100644
--- a/CIME/data/config/xml_schemas/config_machines.xsd
+++ b/CIME/data/config/xml_schemas/config_machines.xsd
@@ -55,6 +55,8 @@
   <xs:element name="ALLOCATE_SPARE_NODES" type="upperBoolean"/>
   <xs:element name="SUPPORTED_BY" type="xs:string"/>
   <xs:element name="MAX_TASKS_PER_NODE" type="AttrElement"/>
+  <xs:element name="MEM_PER_TASK" type="AttrElement"/>
+  <xs:element name="MAX_MEM_PER_NODE" type="AttrElement"/>
   <xs:element name="MAX_GPUS_PER_NODE" type="AttrElement"/>
   <xs:element name="MAX_MPITASKS_PER_NODE" type="AttrElement"/>
   <xs:element name="MAX_CPUTASKS_PER_GPU_NODE" type="AttrElement"/>
@@ -164,6 +166,13 @@
         <!-- MAX_TASKS_PER_NODE: maximum number of threads*tasks per
              shared memory node on this machine-->
         <xs:element ref="MAX_TASKS_PER_NODE" minOccurs="1" maxOccurs="unbounded"/>
+
+        <!-- MEM_PER_TASK: the minimum memory to assign per mpi task (units assigned in config_batch.xml) -->
+        <xs:element ref="MEM_PER_TASK" minOccurs="0" maxOccurs="1"/>
+        <!-- MAX_MEM_PER_NODE: the maximum memory to assign per machine node -->
+        <xs:element ref="MAX_MEM_PER_NODE" minOccurs="0" maxOccurs="1"/>
+
+
         <!-- MAX_GPUS_PER_NODE: maximum number of GPUs per node on this machine-->
         <xs:element ref="MAX_GPUS_PER_NODE" minOccurs="0" maxOccurs="1"/>
         <!-- MAX_MPITASKS_PER_NODE: number of physical PES per shared node on
diff --git a/CIME/data/config/xml_schemas/config_machines_version3.xsd b/CIME/data/config/xml_schemas/config_machines_version3.xsd
index 92b55839fb2..baa46aabad5 100644
--- a/CIME/data/config/xml_schemas/config_machines_version3.xsd
+++ b/CIME/data/config/xml_schemas/config_machines_version3.xsd
@@ -56,6 +56,8 @@
   <xs:element name="ALLOCATE_SPARE_NODES" type="upperBoolean"/>
   <xs:element name="SUPPORTED_BY" type="xs:string"/>
   <xs:element name="MAX_TASKS_PER_NODE" type="AttrElement"/>
+  <xs:element name="MEM_PER_TASK" type="AttrElement"/>
+  <xs:element name="MAX_MEM_PER_NODE" type="AttrElement"/>
   <xs:element name="MAX_GPUS_PER_NODE" type="AttrElement"/>
   <xs:element name="MAX_MPITASKS_PER_NODE" type="AttrElement"/>
   <xs:element name="MAX_CPUTASKS_PER_GPU_NODE" type="AttrElement"/>
@@ -181,6 +183,12 @@
         <!-- MAX_TASKS_PER_NODE: maximum number of threads*tasks per
              shared memory node on this machine-->
         <xs:element ref="MAX_TASKS_PER_NODE" minOccurs="1" maxOccurs="unbounded"/>
+
+        <!-- MEM_PER_TASK: the minimum memory to assign per mpi task (units assigned in config_batch.xml) -->
+        <xs:element ref="MEM_PER_TASK" minOccurs="0" maxOccurs="1"/>
+        <!-- MAX_MEM_PER_NODE: the maximum memory to assign per machine node -->
+        <xs:element ref="MAX_MEM_PER_NODE" minOccurs="0" maxOccurs="1"/>
+
         <!-- MAX_GPUS_PER_NODE: maximum number of GPUs per node on this machine-->
         <xs:element ref="MAX_GPUS_PER_NODE" minOccurs="0" maxOccurs="1"/>
         <!-- MAX_MPITASKS_PER_NODE: number of physical PES per shared node on