diff --git a/llvm/lib/Transforms/Scalar/LoopSink.cpp b/llvm/lib/Transforms/Scalar/LoopSink.cpp
--- a/llvm/lib/Transforms/Scalar/LoopSink.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopSink.cpp
@@ -70,7 +70,7 @@
     cl::desc("Enable MemorySSA for LoopSink in new pass manager"));
 
 static cl::opt<bool> EnableMSSAInLegacyLoopSink(
-    "enable-mssa-in-legacy-loop-sink", cl::Hidden, cl::init(false),
+    "enable-mssa-in-legacy-loop-sink", cl::Hidden, cl::init(true),
     cl::desc("Enable MemorySSA for LoopSink in legacy pass manager"));
 
 /// Return adjusted total frequency of \p BBs.
diff --git a/llvm/test/CodeGen/AMDGPU/opt-pipeline.ll b/llvm/test/CodeGen/AMDGPU/opt-pipeline.ll
--- a/llvm/test/CodeGen/AMDGPU/opt-pipeline.ll
+++ b/llvm/test/CodeGen/AMDGPU/opt-pipeline.ll
@@ -297,6 +297,7 @@
 ; GCN-O1-NEXT:       Basic Alias Analysis (stateless AA impl)
 ; GCN-O1-NEXT:       Function Alias Analysis Results
 ; GCN-O1-NEXT:       Scalar Evolution Analysis
+; GCN-O1-NEXT:       Memory SSA
 ; GCN-O1-NEXT:       Block Frequency Analysis
 ; GCN-O1-NEXT:       Loop Pass Manager
 ; GCN-O1-NEXT:         Loop Sink
@@ -656,6 +657,7 @@
 ; GCN-O2-NEXT:       Basic Alias Analysis (stateless AA impl)
 ; GCN-O2-NEXT:       Function Alias Analysis Results
 ; GCN-O2-NEXT:       Scalar Evolution Analysis
+; GCN-O2-NEXT:       Memory SSA
 ; GCN-O2-NEXT:       Block Frequency Analysis
 ; GCN-O2-NEXT:       Loop Pass Manager
 ; GCN-O2-NEXT:         Loop Sink
@@ -1020,6 +1022,7 @@
 ; GCN-O3-NEXT:       Basic Alias Analysis (stateless AA impl)
 ; GCN-O3-NEXT:       Function Alias Analysis Results
 ; GCN-O3-NEXT:       Scalar Evolution Analysis
+; GCN-O3-NEXT:       Memory SSA
 ; GCN-O3-NEXT:       Block Frequency Analysis
 ; GCN-O3-NEXT:       Loop Pass Manager
 ; GCN-O3-NEXT:         Loop Sink