diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/circular-reference.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/circular-reference.ll
index eeda793..fb239b0 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/circular-reference.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/circular-reference.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
 ; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s
 
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/comdat.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/comdat.ll
index caea48e..a43fa1c 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/comdat.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/comdat.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=THIN %s
 ; RUN: llvm-modextract -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=MERGED %s
 
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/filter-alias.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/filter-alias.ll
index eb0cbe7..200d494 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/filter-alias.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/filter-alias.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=CHECK0 %s
 ; RUN: llvm-modextract -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=CHECK1 %s
 ; CHECK0-NOT: @{{.*}}anon{{.*}}=
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/function-alias.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/function-alias.ll
index 119b821..a1dbd96 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/function-alias.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/function-alias.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=CHECK1 %s
 
 target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/pr33536.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/pr33536.ll
index 661d073..c405c36 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/pr33536.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/pr33536.ll
@@ -1,7 +1,7 @@
 ; Test for a bug specific to the new pass manager where we may build a domtree
 ; to make more precise AA queries for functions.
 ;
-; RUN: opt -aa-pipeline=default -passes='no-op-module' -debug-pass-manager -thinlto-bc -o %t %s
+; RUN: opt -aa-pipeline=default -passes='no-op-module' -debug-pass-manager -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
 ; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s
 
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal-typeid.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal-typeid.ll
index a43db9a..290df00 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal-typeid.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal-typeid.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o %t0 %t
 ; RUN: llvm-modextract -b -n 1 -o %t1 %t
 ; RUN: not llvm-modextract -b -n 2 -o - %t 2>&1 | FileCheck --check-prefix=ERROR %s
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal1.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal1.ll
index 6d18c4f..42a06bd 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal1.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal1.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o %t0 %t
 ; RUN: llvm-modextract -b -n 1 -o %t1 %t
 ; RUN: not llvm-modextract -b -n 2 -o - %t 2>&1 | FileCheck --check-prefix=ERROR %s
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal2.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal2.ll
index fbe618f..02fc3d1 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal2.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal2.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o %t0 %t
 ; RUN: llvm-modextract -b -n 1 -o %t1 %t
 ; RUN: not llvm-modextract -b -n 2 -o - %t 2>&1 | FileCheck --check-prefix=ERROR %s
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc-internal.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc-internal.ll
index 087796b..7ebb30a 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc-internal.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc-internal.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
 ; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s
 
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc.ll
index 66d37d5..fcf5751 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
 ; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s
 
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/split.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/split.ll
index 08ed92e..5502f7a 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/split.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/split.ll
@@ -1,6 +1,6 @@
 ; Generate bitcode files with summary, as well as minimized bitcode without
 ; the debug metadata for the thin link.
-; RUN: opt -thinlto-bc -thin-link-bitcode-file=%t2 -o %t %s
+; RUN: opt -thinlto-bc -thin-link-bitcode-file=%t2 -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o %t0.bc %t
 ; RUN: llvm-modextract -b -n 1 -o %t1.bc %t
 ; RUN: llvm-modextract -b -n 0 -o %t0.thinlink.bc %t2
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/symver.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/symver.ll
index 078825c..8acdd0c 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/symver.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/symver.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -n 1 -o - %t | llvm-dis | FileCheck %s
 
 ; The target assembly parser is required to parse the symver directives
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/unsplittable.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/unsplittable.ll
index 5413e0f..46c87bc 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/unsplittable.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/unsplittable.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -thin-link-bitcode-file=%t2 -o %t %s
+; RUN: opt -thinlto-bc -thin-link-bitcode-file=%t2 -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-dis -o - %t | FileCheck %s
 ; RUN: llvm-bcanalyzer -dump %t | FileCheck --check-prefix=BCA %s
 ; When not splitting the module, the thin link bitcode file should simply be a
@@ -28,7 +28,8 @@
   ret void
 }
 
-; CHECK: !llvm.module.flags = !{![[FLAG:[0-9]+]]}
-; CHECK: ![[FLAG]] = !{i32 1, !"ThinLTO", i32 0}
+; CHECK: !llvm.module.flags = !{![[FLAG1:[0-9]+]], ![[FLAG2:[0-9]+]]}
+; CHECK: ![[FLAG1]] = !{i32 1, !"EnableSplitLTOUnit", i32 1}
+; CHECK: ![[FLAG2]] = !{i32 1, !"ThinLTO", i32 0}
 
 !0 = !{i32 0, !"typeid"}
diff --git a/llvm/test/Transforms/ThinLTOBitcodeWriter/x86/module-asm.ll b/llvm/test/Transforms/ThinLTOBitcodeWriter/x86/module-asm.ll
index 15e4778..587ab3f 100644
--- a/llvm/test/Transforms/ThinLTOBitcodeWriter/x86/module-asm.ll
+++ b/llvm/test/Transforms/ThinLTOBitcodeWriter/x86/module-asm.ll
@@ -1,4 +1,4 @@
-; RUN: opt -thinlto-bc -o %t %s
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
 ; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s