diff --git a/build_tests/simple/run_builder.rb b/build_tests/simple/run_builder.rb
deleted file mode 100644
index 2a37de6..0000000
--- a/build_tests/simple/run_builder.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-class MyObject < Rscons::Builder
-  def run(options)
-    target, sources, cache, env, vars = options.values_at(:target, :sources, :cache, :env, :vars)
-    env.run_builder(env.builders["Object"].new(env: env, target: target, sources: sources, cache: cache, vars: vars), target, sources, cache, vars)
-  end
-end
-
-build do
-  Environment.new do |env|
-    env.add_builder(MyObject)
-    env.MyObject("simple.o", "simple.c")
-    env.Program("simple.exe", "simple.o")
-  end
-end
diff --git a/lib/rscons/environment.rb b/lib/rscons/environment.rb
index 6b735b4..e2774d2 100644
--- a/lib/rscons/environment.rb
+++ b/lib/rscons/environment.rb
@@ -281,8 +281,7 @@ module Rscons
                                  job[:target],
                                  job[:sources],
                                  cache,
-                                 job[:vars],
-                                 allow_delayed_execution: true)
+                                 job[:vars])
             unless result
               failure = "Failed to build #{job[:target]}"
               Ansi.write($stderr, :red, failure, :reset, "\n")
@@ -515,10 +514,6 @@ module Rscons
     # @param options [Hash]
     #   @since 1.10.0
     #   Options.
-    # @option options [Boolean] :allow_delayed_execution
-    #   @since 1.10.0
-    #   Allow a threaded command to be scheduled but not yet completed before
-    #   this method returns.
     #
     # @return [String,false] Return value from the {Builder}'s +run+ method.
     def run_builder(builder, target, sources, cache, vars, options = {})
@@ -554,19 +549,6 @@ module Rscons
         # with it when the threaded command completes.
         rv.build_operation = build_operation
         start_threaded_command(rv)
-        unless options[:allow_delayed_execution]
-          # Delayed command execution is not allowed, so we need to execute
-          # the command and finalize the builder now.
-          tc = wait_for_threaded_commands(which: [rv])
-          rv = finalize_builder(tc)
-          if rv
-            call_build_hooks[:post]
-          else
-            unless @echo == :command
-              print_failed_command(tc.command)
-            end
-          end
-        end
       else
         call_build_hooks[:post] if rv
       end
diff --git a/spec/build_tests_spec.rb b/spec/build_tests_spec.rb
index 6d6c8bf..1c8371a 100644
--- a/spec/build_tests_spec.rb
+++ b/spec/build_tests_spec.rb
@@ -843,28 +843,6 @@ EOF
     end
   end
 
-  context "backward compatibility" do
-    it "allows a builder to call Environment#run_builder in a non-threaded manner" do
-      test_dir("simple")
-      result = run_rscons(rsconscript: "run_builder.rb")
-      expect(result.stderr).to eq ""
-      expect(lines(result.stdout)).to include *[
-        "CC simple.o",
-        "LD simple.exe",
-      ]
-    end
-
-    it "prints the failed build command for a threaded builder when called via Environment#run_builder without delayed execution" do
-      test_dir("simple")
-      File.open("simple.c", "wb") do |fh|
-        fh.write("FOOBAR")
-      end
-      result = run_rscons(rsconscript: "run_builder.rb")
-      expect(result.stderr).to match /Failed to build/
-      expect(result.stdout).to match /Failed command was: gcc/
-    end
-  end
-
   context "CFile builder" do
     it "builds a .c file using flex and bison" do
       test_dir("cfile")