diff --git a/Tools/scripts/size_compare_branches.py b/Tools/scripts/size_compare_branches.py
index 750691effe..06d4120673 100755
--- a/Tools/scripts/size_compare_branches.py
+++ b/Tools/scripts/size_compare_branches.py
@@ -19,6 +19,7 @@ Output is placed into ../ELF_DIFF_[VEHICLE_NAME]
 import copy
 import optparse
 import os
+import pathlib
 import shutil
 import string
 import subprocess
@@ -317,6 +318,9 @@ class SizeCompareBranches(object):
         if extra_hwdef is not None:
             waf_configure_args.extend(["--extra-hwdef", extra_hwdef])
 
+        if self.run_elf_diff:
+            waf_configure_args.extend(["--debug-symbols"])
+
         if jobs is None:
             jobs = self.jobs
         if jobs is not None:
@@ -348,6 +352,8 @@ class SizeCompareBranches(object):
             self.run_waf(bootloader_waf_configure_args, show_output=False, source_dir=source_dir)
             self.run_waf([v], show_output=False, source_dir=source_dir)
         self.run_program("rsync", ["rsync", "-ap", "build/", outdir], cwd=source_dir)
+        if source_dir is not None:
+            pathlib.Path(outdir, "scb_sourcepath.txt").write_text(source_dir)
 
     def vehicles_to_build_for_board_info(self, board_info):
         vehicles_to_build = []
@@ -450,6 +456,7 @@ class SizeCompareBranches(object):
             tasks.append((board, self.master_commit, outdir_1, vehicles_to_build, self.extra_hwdef_master))
             outdir_2 = os.path.join(tmpdir, "out-branch-%s" % (board,))
             tasks.append((board, self.branch, outdir_2, vehicles_to_build, self.extra_hwdef_branch))
+        self.tasks = tasks
 
         if self.parallel_copies is not None:
             self.run_build_tasks_in_parallel(tasks)
@@ -487,9 +494,22 @@ class SizeCompareBranches(object):
                 "--old_alias", "%s %s" % (master_branch, elf_filename),
                 "--new_alias", "%s %s" % (branch, elf_filename),
                 "--html_dir", "../ELF_DIFF_%s_%s" % (board, vehicle),
+            ]
+
+            try:
+                master_source_prefix = result_master["vehicle"][vehicle]["source_path"]
+                branch_source_prefix = result_branch["vehicle"][vehicle]["source_path"]
+                elf_diff_commandline.extend([
+                    "--old_source_prefix", master_source_prefix,
+                    "--new_source_prefix", branch_source_prefix,
+                ])
+            except KeyError:
+                pass
+
+            elf_diff_commandline.extend([
                 os.path.join(master_elf_dir, elf_filename),
                 os.path.join(new_elf_dir, elf_filename)
-            ]
+            ])
 
             self.run_program("SCB", elf_diff_commandline)
 
@@ -614,6 +634,8 @@ class SizeCompareBranches(object):
             "vehicle": {},
         }
 
+        have_source_trees = self.parallel_copies is not None and len(self.tasks) <= self.parallel_copies
+
         for vehicle in vehicles_to_build:
             if vehicle == 'bootloader' and board in self.bootloader_blacklist:
                 continue
@@ -621,13 +643,21 @@ class SizeCompareBranches(object):
             result["vehicle"][vehicle] = {}
             v = result["vehicle"][vehicle]
             v["bin_filename"] = self.vehicle_map[vehicle] + '.bin'
-            v["bin_dir"] = os.path.join(outdir, board, "bin")
 
             elf_dirname = "bin"
             if vehicle == 'bootloader':
                 # elfs for bootloaders are in the bootloader directory...
                 elf_dirname = "bootloader"
-            elf_dir = os.path.join(outdir, board, elf_dirname)
+            elf_basedir = outdir
+            if have_source_trees:
+                try:
+                    v["source_path"] = pathlib.Path(outdir, "scb_sourcepath.txt").read_text()
+                    elf_basedir = os.path.join(v["source_path"], 'build')
+                    self.progress("Have source trees")
+                except FileNotFoundError:
+                    pass
+            v["bin_dir"] = os.path.join(elf_basedir, board, "bin")
+            elf_dir = os.path.join(elf_basedir, board, elf_dirname)
             v["elf_dir"] = elf_dir
             v["elf_filename"] = self.vehicle_map[vehicle]