Index: lib/Transforms/Utils/SimplifyCFG.cpp
===================================================================
--- lib/Transforms/Utils/SimplifyCFG.cpp
+++ lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2966,6 +2966,14 @@
   PStore->getAAMetadata(AAMD, /*Merge=*/false);
   PStore->getAAMetadata(AAMD, /*Merge=*/true);
   SI->setAAMetadata(AAMD);
+  unsigned PAlignment = PStore->getAlignment();
+  unsigned QAlignment = QStore->getAlignment();
+  if (unsigned MinAlignment = std::min(PAlignment, QAlignment))
+    // Choose the minimum of all non-zero alignments.
+    SI->setAlignment(MinAlignment);
+  else if (unsigned MaxAlignment = std::max(PAlignment, QAlignment))
+    // Choose the first non-zero alignment, if any.
+    SI->setAlignment(MaxAlignment);
 
   QStore->eraseFromParent();
   PStore->eraseFromParent();
Index: test/Transforms/SimplifyCFG/preserve-store-alignment.ll
===================================================================
--- test/Transforms/SimplifyCFG/preserve-store-alignment.ll
+++ test/Transforms/SimplifyCFG/preserve-store-alignment.ll
@@ -25,7 +25,7 @@
 ; CHECK-NEXT:    [[TMP7:%.*]] = xor i1 [[TOBOOL5]], true
 ; CHECK-NEXT:    [[TMP8:%.*]] = or i1 [[TMP6]], [[TMP7]]
 ; CHECK-NEXT:    br i1 [[TMP8]], label [[TMP9:%.*]], label [[TMP10:%.*]]
-; CHECK:         store <2 x i64> [[DOT]], <2 x i64>* bitcast (i64* getelementptr inbounds (%struct.Counters, %struct.Counters* @counters, i64 0, i32 1) to <2 x i64>*)
+; CHECK:         store <2 x i64> [[DOT]], <2 x i64>* bitcast (i64* getelementptr inbounds (%struct.Counters, %struct.Counters* @counters, i64 0, i32 1) to <2 x i64>*), align 8
 ; CHECK-NEXT:    br label [[TMP10]]
 ; CHECK:         ret i32 0
 ;