diff --git a/tests/run-make/const_fn_mir/Makefile b/tests/run-make/const_fn_mir/Makefile
index 6d72c12272303..3399446130d74 100644
--- a/tests/run-make/const_fn_mir/Makefile
+++ b/tests/run-make/const_fn_mir/Makefile
@@ -3,9 +3,4 @@ include ../tools.mk
 
 all:
 	$(RUSTC) main.rs --emit=mir -o "$(TMPDIR)"/dump.mir
-
-ifdef RUSTC_BLESS_TEST
-	cp "$(TMPDIR)"/dump.mir dump.mir
-else
-	$(DIFF) dump.mir "$(TMPDIR)"/dump.mir
-endif
+	$(RUSTC_TEST_OP) "$(TMPDIR)"/dump.mir dump.mir
diff --git a/tests/run-make/metadata-dep-info/Makefile b/tests/run-make/metadata-dep-info/Makefile
index f9043f214338c..d48cbe0f29505 100644
--- a/tests/run-make/metadata-dep-info/Makefile
+++ b/tests/run-make/metadata-dep-info/Makefile
@@ -1,11 +1,5 @@
 include ../tools.mk
 
-ifdef RUSTC_BLESS_TEST
-    RUSTC_TEST_OP = cp
-else
-    RUSTC_TEST_OP = $(DIFF)
-endif
-
 all:
 	$(RUSTC) --emit=metadata,dep-info --crate-type lib dash-separated.rs -C extra-filename=_something-extra
 	# Strip TMPDIR since it is a machine specific absolute path
diff --git a/tests/run-make/overwrite-input/Makefile b/tests/run-make/overwrite-input/Makefile
index c62b5aab190db..721bf62b26b5d 100644
--- a/tests/run-make/overwrite-input/Makefile
+++ b/tests/run-make/overwrite-input/Makefile
@@ -3,11 +3,5 @@ include ../tools.mk
 all:
 	$(RUSTC) main.rs -o main.rs 2> $(TMPDIR)/file.stderr || echo "failed successfully"
 	$(RUSTC) main.rs -o . 2> $(TMPDIR)/folder.stderr || echo "failed successfully"
-
-ifdef RUSTC_BLESS_TEST
-	cp "$(TMPDIR)"/file.stderr file.stderr
-	cp "$(TMPDIR)"/folder.stderr folder.stderr
-else
-	$(DIFF) file.stderr "$(TMPDIR)"/file.stderr
-	$(DIFF) folder.stderr "$(TMPDIR)"/folder.stderr
-endif
+	$(RUSTC_TEST_OP) "$(TMPDIR)"/file.stderr file.stderr
+	$(RUSTC_TEST_OP) "$(TMPDIR)"/folder.stderr folder.stderr
diff --git a/tests/run-make/raw-dylib-alt-calling-convention/Makefile b/tests/run-make/raw-dylib-alt-calling-convention/Makefile
index 1744c431f9c99..14d23a5d20106 100644
--- a/tests/run-make/raw-dylib-alt-calling-convention/Makefile
+++ b/tests/run-make/raw-dylib-alt-calling-convention/Makefile
@@ -16,17 +16,9 @@ else
 endif
 
 	"$(TMPDIR)"/driver > "$(TMPDIR)"/output.txt
-ifdef RUSTC_BLESS_TEST
-	cp "$(TMPDIR)"/output.txt output.txt
-else
-	$(DIFF) output.txt "$(TMPDIR)"/output.txt
-endif
+	$(RUSTC_TEST_OP) "$(TMPDIR)"/output.txt output.txt
 
 ifdef IS_MSVC
 	"$(TMPDIR)"/driver true > "$(TMPDIR)"/output.msvc.txt
-ifdef RUSTC_BLESS_TEST
-	cp "$(TMPDIR)"/output.msvc.txt output.msvc.txt
-else
-	$(DIFF) output.msvc.txt "$(TMPDIR)"/output.msvc.txt
-endif
+	$(RUSTC_TEST_OP) "$(TMPDIR)"/output.msvc.txt output.msvc.txt
 endif
diff --git a/tests/run-make/raw-dylib-import-name-type/Makefile b/tests/run-make/raw-dylib-import-name-type/Makefile
index 67152329807cf..901d3e861c21a 100644
--- a/tests/run-make/raw-dylib-import-name-type/Makefile
+++ b/tests/run-make/raw-dylib-import-name-type/Makefile
@@ -14,9 +14,4 @@ else
 	$(CC) "$(TMPDIR)"/extern.obj extern.gnu.def --no-leading-underscore -shared -o "$(TMPDIR)"/extern.dll
 endif
 	"$(TMPDIR)"/driver > "$(TMPDIR)"/output.txt
-
-ifdef RUSTC_BLESS_TEST
-	cp "$(TMPDIR)"/output.txt output.txt
-else
-	$(DIFF) output.txt "$(TMPDIR)"/output.txt
-endif
+	$(RUSTC_TEST_OP) "$(TMPDIR)"/output.txt output.txt
diff --git a/tests/run-make/raw-dylib-inline-cross-dylib/Makefile b/tests/run-make/raw-dylib-inline-cross-dylib/Makefile
index 6d1d04bfd37d2..195b5fda56fd3 100644
--- a/tests/run-make/raw-dylib-inline-cross-dylib/Makefile
+++ b/tests/run-make/raw-dylib-inline-cross-dylib/Makefile
@@ -27,9 +27,4 @@ else
 	$(CC) "$(TMPDIR)"/extern_2.obj -shared -o "$(TMPDIR)"/extern_2.dll
 endif
 	$(call RUN,driver) > "$(TMPDIR)"/output.txt
-
-ifdef RUSTC_BLESS_TEST
-	cp "$(TMPDIR)"/output.txt output.txt
-else
-	$(DIFF) output.txt "$(TMPDIR)"/output.txt
-endif
+	$(RUSTC_TEST_OP) "$(TMPDIR)"/output.txt output.txt
diff --git a/tests/run-make/raw-dylib-link-ordinal/Makefile b/tests/run-make/raw-dylib-link-ordinal/Makefile
index 374a0b59de322..49e959cdb5b8e 100644
--- a/tests/run-make/raw-dylib-link-ordinal/Makefile
+++ b/tests/run-make/raw-dylib-link-ordinal/Makefile
@@ -14,9 +14,4 @@ else
 	$(CC) "$(TMPDIR)"/exporter.obj exporter.def -shared -o "$(TMPDIR)"/exporter.dll
 endif
 	"$(TMPDIR)"/driver > "$(TMPDIR)"/output.txt
-
-ifdef RUSTC_BLESS_TEST
-	cp "$(TMPDIR)"/output.txt output.txt
-else
-	$(DIFF) output.txt "$(TMPDIR)"/output.txt
-endif
+	$(RUSTC_TEST_OP) "$(TMPDIR)"/output.txt output.txt
diff --git a/tests/run-make/raw-dylib-stdcall-ordinal/Makefile b/tests/run-make/raw-dylib-stdcall-ordinal/Makefile
index 178c15ab3dee4..70e4de62c1a9e 100644
--- a/tests/run-make/raw-dylib-stdcall-ordinal/Makefile
+++ b/tests/run-make/raw-dylib-stdcall-ordinal/Makefile
@@ -15,9 +15,4 @@ else
 	$(CC) "$(TMPDIR)"/exporter.obj exporter-gnu.def -shared -o "$(TMPDIR)"/exporter.dll
 endif
 	"$(TMPDIR)"/driver > "$(TMPDIR)"/actual_output.txt
-
-ifdef RUSTC_BLESS_TEST
-	cp "$(TMPDIR)"/actual_output.txt expected_output.txt
-else
-	$(DIFF) expected_output.txt "$(TMPDIR)"/actual_output.txt
-endif
+	$(RUSTC_TEST_OP) "$(TMPDIR)"/actual_output.txt expected_output.txt
diff --git a/tests/run-make/silly-file-names/Makefile b/tests/run-make/silly-file-names/Makefile
index a09bdb1c5329e..e51266c0880b0 100644
--- a/tests/run-make/silly-file-names/Makefile
+++ b/tests/run-make/silly-file-names/Makefile
@@ -3,12 +3,6 @@
 
 include ../tools.mk
 
-ifdef RUSTC_BLESS_TEST
-    RUSTC_TEST_OP = cp
-else
-    RUSTC_TEST_OP = $(DIFF)
-endif
-
 all:
 	echo '"comes from a file with a name that begins with <"' > "$(TMPDIR)/<leading-lt"
 	echo '"comes from a file with a name that ends with >"' > "$(TMPDIR)/trailing-gt>"
diff --git a/tests/run-make/tools.mk b/tests/run-make/tools.mk
index 6121a91e9203f..1d4e911138920 100644
--- a/tests/run-make/tools.mk
+++ b/tests/run-make/tools.mk
@@ -21,6 +21,28 @@ CGREP := "$(S)/src/etc/cat-and-grep.sh"
 # diff with common flags for multi-platform diffs against text output
 DIFF := diff -u --strip-trailing-cr
 
+# With RUSTC_TEST_OP you can elegantly support blessing of run-make tests. Do
+# like this in a Makefile recipe:
+#
+#   "$(TMPDIR)"/your-test > "$(TMPDIR)"/your-test.run.stdout
+#   $(RUSTC_TEST_OP) "$(TMPDIR)"/your-test.run.stdout your-test.run.stdout
+#
+# When running the test normally with
+#
+#   ./x test tests/run-make/your-test
+#
+# the actual output will be diffed against the expected output. When running in
+# bless-mode with
+#
+#   ./x test --bless tests/run-make/your-test
+#
+# the actual output will be blessed as the expected output.
+ifdef RUSTC_BLESS_TEST
+    RUSTC_TEST_OP = cp
+else
+    RUSTC_TEST_OP = $(DIFF)
+endif
+
 # Some of the Rust CI platforms use `/bin/dash` to run `shell` script in
 # Makefiles. Other platforms, including many developer platforms, default to
 # `/bin/bash`. (In many cases, `make` is actually using `/bin/sh`, but `sh`
diff --git a/tests/run-make/unknown-mod-stdin/Makefile b/tests/run-make/unknown-mod-stdin/Makefile
index c1931765382e8..313b0ba837e83 100644
--- a/tests/run-make/unknown-mod-stdin/Makefile
+++ b/tests/run-make/unknown-mod-stdin/Makefile
@@ -4,12 +4,5 @@ include ../tools.mk
 
 all:
 	echo 'mod unknown;' | $(RUSTC) --crate-type rlib - >$(TMPDIR)/unknown-mod.stdout 2>$(TMPDIR)/unknown-mod.stderr || echo "failed successfully"
-
-# Bless like this: RUSTC_BLESS_TEST=1 ./x.py test tests/run-make/unknown-mod-stdin
-ifdef RUSTC_BLESS_TEST
-	cp "$(TMPDIR)"/unknown-mod.stdout unknown-mod.stdout
-	cp "$(TMPDIR)"/unknown-mod.stderr unknown-mod.stderr
-else
-	$(DIFF) unknown-mod.stdout "$(TMPDIR)"/unknown-mod.stdout
-	$(DIFF) unknown-mod.stderr "$(TMPDIR)"/unknown-mod.stderr
-endif
+	$(RUSTC_TEST_OP) "$(TMPDIR)"/unknown-mod.stdout unknown-mod.stdout
+	$(RUSTC_TEST_OP) "$(TMPDIR)"/unknown-mod.stderr unknown-mod.stderr