diff --git a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
--- a/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -219,6 +219,11 @@
 INITIALIZE_PASS(AArch64LoadStoreOpt, "aarch64-ldst-opt",
                 AARCH64_LOAD_STORE_OPT_NAME, false, false)
 
+enum NarrowStoreTy {
+  N8_STORE,
+  N16_STORE,
+};
+
 static bool isNarrowStore(unsigned Opc) {
   switch (Opc) {
   default:
@@ -231,6 +236,20 @@
   }
 }
 
+static NarrowStoreTy getNarrowStoreType(unsigned Opc) {
+  switch (Opc) {
+  default:
+    llvm_unreachable("Opcode is not a narrow store");
+
+  case AArch64::STRBBui:
+  case AArch64::STURBBi:
+    return NarrowStoreTy::N8_STORE;
+  case AArch64::STRHHui:
+  case AArch64::STURHHi:
+    return NarrowStoreTy::N16_STORE;
+  }
+}
+
 // These instruction set memory tag and either keep memory contents unchanged or
 // set it to zero, ignoring the address part of the source register.
 static bool isTagStore(const MachineInstr &MI) {
@@ -1334,10 +1353,15 @@
   if (!PairIsValidLdStrOpc)
     return false;
 
-  // FIXME: We don't support merging narrow stores with mixed scaled/unscaled
-  // offsets.
-  if (isNarrowStore(OpcA) || isNarrowStore(OpcB))
+  bool IsNarrowStoreA = isNarrowStore(OpcA);
+  bool IsNarrowStoreB = isNarrowStore(OpcB);
+  // skip if A and B aren't in the same store class. Narrow and wide stores
+  // can't be merged.
+  if (IsNarrowStoreA != IsNarrowStoreB)
     return false;
+  // Check if we can merge two narrow stores.
+  if (IsNarrowStoreA && IsNarrowStoreB)
+    return getNarrowStoreType(OpcA) == getNarrowStoreType(OpcB);
 
   // The STR<S,D,Q,W,X>pre - STR<S,D,Q,W,X>ui and
   // LDR<S,D,Q,W,X>pre-LDR<S,D,Q,W,X>ui
diff --git a/llvm/test/CodeGen/AArch64/str-narrow-zero-merge.mir b/llvm/test/CodeGen/AArch64/str-narrow-zero-merge.mir
--- a/llvm/test/CodeGen/AArch64/str-narrow-zero-merge.mir
+++ b/llvm/test/CodeGen/AArch64/str-narrow-zero-merge.mir
@@ -29,8 +29,7 @@
 body:             |
   bb.0.entry:
     ; CHECK-LABEL: name: merge_scaled_str_with_unscaled_8
-    ; CHECK: STRBBui $wzr, $x0, 4 :: (store (s8))
-    ; CHECK-NEXT: STURBBi $wzr, $x0, 5 :: (store (s8))
+    ; CHECK: STRHHui $wzr, $x0, 2 :: (store (s8))
     ; CHECK-NEXT: RET undef $lr
     STRBBui $wzr, $x0, 4 :: (store (s8))
     STURBBi $wzr, $x0, 5 :: (store (s8))
@@ -41,8 +40,7 @@
 body:             |
   bb.0.entry:
     ; CHECK-LABEL: name: merge_unscaled_str_with_scaled_8
-    ; CHECK: STURBBi $wzr, $x0, 4 :: (store (s8))
-    ; CHECK-NEXT: STRBBui $wzr, $x0, 5 :: (store (s8))
+    ; CHECK: STURHHi $wzr, $x0, 4 :: (store (s8))
     ; CHECK-NEXT: RET undef $lr
     STURBBi $wzr, $x0, 4 :: (store (s8))
     STRBBui $wzr, $x0, 5 :: (store (s8))
@@ -75,8 +73,7 @@
 body:             |
   bb.0.entry:
     ; CHECK-LABEL: name: merge_scaled_str_with_unscaled_16
-    ; CHECK: STRHHui $wzr, $x0, 2 :: (store (s16))
-    ; CHECK-NEXT: STURHHi $wzr, $x0, 6 :: (store (s16))
+    ; CHECK: STRWui $wzr, $x0, 1 :: (store (s16))
     ; CHECK-NEXT: RET undef $lr
     STRHHui $wzr, $x0, 2 :: (store (s16))
     STURHHi $wzr, $x0, 6 :: (store (s16))
@@ -87,8 +84,7 @@
 body:             |
   bb.0.entry:
     ; CHECK-LABEL: name: merge_unscaled_str_with_scaled_16
-    ; CHECK: STURHHi $wzr, $x0, 4 :: (store (s16))
-    ; CHECK-NEXT: STRHHui $wzr, $x0, 3 :: (store (s16))
+    ; CHECK: STURWi $wzr, $x0, 4 :: (store (s16))
     ; CHECK-NEXT: RET undef $lr
     STURHHi $wzr, $x0, 4 :: (store (s16))
     STRHHui $wzr, $x0, 3 :: (store (s16))