diff --git a/tools/burnin b/tools/burnin
index a7ac6f65a4cdfba248a06711ff2bbf1ba4dd069a..54fbf9a40d6b3b0c907540134ef433d2ee501d47 100755
--- a/tools/burnin
+++ b/tools/burnin
@@ -124,6 +124,14 @@ OPTIONS = [
   cli.cli_option("--disk-growth", dest="disk_growth", help="Disk growth",
                  default="128m", type="string", metavar="<size,size,...>"),
   cli.cli_option("--mem-size", dest="mem_size", help="Memory size",
+                 default=None, type="unit", metavar="<size>",
+                 completion_suggest=("128M 256M 512M 1G 4G 8G"
+                                     " 12G 16G").split()),
+  cli.cli_option("--maxmem-size", dest="maxmem_size", help="Max Memory size",
+                 default=256, type="unit", metavar="<size>",
+                 completion_suggest=("128M 256M 512M 1G 4G 8G"
+                                     " 12G 16G").split()),
+  cli.cli_option("--minmem-size", dest="minmem_size", help="Min Memory size",
                  default=128, type="unit", metavar="<size>",
                  completion_suggest=("128M 256M 512M 1G 4G 8G"
                                      " 12G 16G").split()),
@@ -442,6 +450,12 @@ class Burner(object):
     if len(args) < 1 or options.os is None:
       Usage()
 
+    if options.mem_size:
+      options.maxmem_size = options.mem_size
+      options.minmem_size = options.mem_size
+    elif options.minmem_size > options.maxmem_size:
+      Err("Maximum memory lower than minimum memory")
+
     supported_disk_templates = (constants.DT_DISKLESS,
                                 constants.DT_FILE,
                                 constants.DT_SHARED_FILE,
@@ -476,8 +490,8 @@ class Burner(object):
     self.opts = options
     self.instances = args
     self.bep = {
-      constants.BE_MINMEM: options.mem_size,
-      constants.BE_MAXMEM: options.mem_size,
+      constants.BE_MINMEM: options.minmem_size,
+      constants.BE_MAXMEM: options.maxmem_size,
       constants.BE_VCPUS: options.vcpu_count,
       }
 
@@ -589,6 +603,18 @@ class Burner(object):
       remove_instance = lambda name: lambda: self.to_rem.append(name)
       self.ExecOrQueue(instance, [op], post_process=remove_instance(instance))
 
+  @_DoBatch(False)
+  def BurnModifyRuntimeMemory(self):
+    """Alter the runtime memory."""
+    Log("Setting instance runtime memory")
+    for instance in self.instances:
+      Log("instance %s", instance, indent=1)
+      tgt_mem = self.bep[constants.BE_MINMEM]
+      op = opcodes.OpInstanceSetParams(instance_name=instance,
+                                       runtime_mem=tgt_mem)
+      Log("Set memory to %s MB", tgt_mem, indent=2)
+      self.ExecOrQueue(instance, [op])
+
   @_DoBatch(False)
   def BurnGrowDisks(self):
     """Grow both the os and the swap disks by the requested amount, if any."""
@@ -998,6 +1024,10 @@ class Burner(object):
     has_err = True
     try:
       self.BurnCreateInstances()
+
+      if self.bep[constants.BE_MINMEM] < self.bep[constants.BE_MAXMEM]:
+        self.BurnModifyRuntimeMemory()
+
       if opts.do_replace1 and opts.disk_template in constants.DTS_INT_MIRROR:
         self.BurnReplaceDisks1D8()
       if (opts.do_replace2 and len(self.nodes) > 2 and