Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -12638,8 +12638,18 @@
   // Check #2.
   if (!isLoad) {
     SDValue Val = cast<StoreSDNode>(N)->getValue();
-    if (Val == BasePtr || BasePtr.getNode()->isPredecessorOf(Val.getNode()))
+    if (Val == BasePtr)
       return false;
+    if (BasePtr.getNode()->isPredecessorOf(Val.getNode())) {
+      // Check whether the store is in the final user of the base pointer.
+      for (auto *U : BasePtr.getNode()->uses()) {
+        if (Val.getNode() == U)
+          return false;
+        if (U->isPredecessorOf(N))
+          continue;
+        return false;
+      }
+    }
   }
 
   // Caches for hasPredecessorHelper.
Index: test/CodeGen/ARM/dsp-loop-indexing.ll
===================================================================
--- test/CodeGen/ARM/dsp-loop-indexing.ll
+++ test/CodeGen/ARM/dsp-loop-indexing.ll
@@ -7,15 +7,13 @@
 
 ; CHECK-LABEL: test_qadd_2
 ; CHECK: @ %loop
-; TODO: pre-inc str
 
 ; CHECK-DEFAULT: ldr{{.*}}, #4]
 ; CHECK-DEFAULT: ldr{{.*}}, #4]
 ; CHECK-DEFAULT: str{{.*}}, #4]
 ; CHECK-DEFAULT: ldr{{.*}}, #8]!
 ; CHECK-DEAFULT: ldr{{.*}}, #8]!
-; CHECK-DEFAULT: str{{.*}}, #8]
-; CHECK-DEFAULT: add{{.*}}, #8
+; CHECK-DEFAULT: str{{.*}}, #8]!
 
 ; CHECK-COMPLEX: ldr{{.*}}, #8]!
 ; CHECK-COMPLEX: ldr{{.*}}, #8]!
@@ -116,8 +114,6 @@
 ; CHECK-LABEL: test_qadd_3
 ; CHECK: @ %loop
 
-; TODO: pre-inc str
-
 ; CHECK-DEFAULT: ldr{{.*}}, #4]
 ; CHECK-DEFAULT: ldr{{.*}}, #4]
 ; CHECK-DEFAULT: str{{.*}}, #4]
@@ -126,8 +122,7 @@
 ; CHECK-DEFAULT: str{{.*}}, #8]
 ; CHECK-DEFAULT: ldr{{.*}}, #12]!
 ; CHECK-DEFAULT: ldr{{.*}}, #12]!
-; CHECK-DEFAULT: str{{.*}}, #12]
-; CHECK-DEFAULT: add{{.*}}, #12
+; CHECK-DEFAULT: str{{.*}}, #12]!
 
 ; CHECK-COMPLEX: ldr{{.*}}, #12]!
 ; CHECK-COMPLEX: ldr{{.*}}, #12]!
@@ -184,8 +179,6 @@
 ; CHECK-LABEL: test_qadd_4
 ; CHECK: @ %loop
 
-; TODO: pre-inc store
-
 ; CHECK-DEFAULT: ldr{{.*}}, #4]
 ; CHECK-DEFAULT: ldr{{.*}}, #4]
 ; CHECK-DEFAULT: str{{.*}}, #4]
@@ -197,8 +190,7 @@
 ; CHECK-DEFAULT: str{{.*}}, #12]
 ; CHECK-DEFAULT: ldr{{.*}}, #16]!
 ; CHECK-DEFAULT: ldr{{.*}}, #16]!
-; CHECK-DEFAULT: str{{.*}}, #16]
-; CHECK-DEFAULT: add{{.*}}, #16
+; CHECK-DEFAULT: str{{.*}}, #16]!
 
 ; CHECK-COMPLEX: ldr{{.*}}, #16]!
 ; CHECK-COMPLEX: ldr{{.*}}, #16]!
@@ -265,15 +257,13 @@
 
 ; CHECK-LABEL: test_qadd16_2
 ; CHECK: @ %loop
-; TODO: pre-inc store.
 
 ; CHECK-DEFAULT: ldr{{.*}}, #4]
 ; CHECK-DEFAULT: ldr{{.*}}, #4]
 ; CHECK-DEFAULT: str{{.*}}, #8]
 ; CHECK-DEFAULT: ldr{{.*}}, #8]!
 ; CHECK-DEFAULT: ldr{{.*}}, #8]!
-; CHECK-DEFAULT: str{{.*}}, #16]
-; CHECK-DEFAULT: add{{.*}}, #16
+; CHECK-DEFAULT: str{{.*}}, #16]!
 
 ; CHECK-COMPLEX: ldr{{.*}}, #8]!
 ; CHECK-COMPLEX: ldr{{.*}}, #8]!
Index: test/CodeGen/ARM/loop-indexing.ll
===================================================================
--- test/CodeGen/ARM/loop-indexing.ll
+++ test/CodeGen/ARM/loop-indexing.ll
@@ -190,8 +190,7 @@
 ; CHECK-DEFAULT: str{{.*}}, #12]
 ; CHECK-DEFAULT: ldrb{{.*}}, #4]!
 ; CHECK-DEFAULT: ldrb{{.*}}, #4]!
-; CHECK-DEFAULT: str{{.*}}, #16]
-; CHECK-DEFAULT: add{{.*}}, #16
+; CHECK-DEFAULT: str{{.*}}, #16]!
 
 ; CHECK-COMPLEX: ldrb
 ; CHECK-COMPLEX: ldrb
@@ -317,8 +316,7 @@
 ; CHECK-DEFAULT: str{{.*}}, #12]
 ; CHECK-DEFAULT: ldrsh{{.*}}, #8]!
 ; CHECK-DEFAULT: ldrb{{.*}}, #4]!
-; CHECK-DEFAULT: str{{.*}}, #16]
-; CHECK-DEFAULT: add{{.*}}, #16
+; CHECK-DEFAULT: str{{.*}}, #16]!
 
 ; CHECK-COMPLEX: ldrsh
 ; CHECK-COMPLEX: ldrb
@@ -444,8 +442,7 @@
 ; CHECK-DEFAULT: str{{.*}}, #12]
 ; CHECK-DEFAULT: ldrsh{{.*}}, #8]!
 ; CHECK-DEFAULT: ldrsh{{.*}}, #8]!
-; CHECK-DEFAULT: str{{.*}}, #16]
-; CHECK-DEFAULT: add{{.*}}, #16
+; CHECK-DEFAULT: str{{.*}}, #16]!
 
 ; CHECK-COMPLEX: ldrsh
 ; CHECK-COMPLEX: ldrsh
@@ -1145,8 +1142,7 @@
 ; CHECK-DEFAULT: str{{.*}}, #12]
 ; CHECK-DEFAULT: ldr{{.*}}, #16]!
 ; CHECK-DEFAULT: ldr{{.*}}, #16]!
-; CHECK-DEFAULT: str{{.*}}, #16]
-; CHECK-DEFAULT: add{{.*}}, #16
+; CHECK-DEFAULT: str{{.*}}, #16]!
 
 ; TODO: Higher complexity results in 22 instructions vs 20.
 ; CHECK-COMPLEX-NOT: ldr{{.*}}, #16]!
Index: test/CodeGen/ARM/pre-inc-store.ll
===================================================================
--- /dev/null
+++ test/CodeGen/ARM/pre-inc-store.ll
@@ -0,0 +1,24 @@
+; RUN: llc -mtriple=thumbv8m.main %s -o - | FileCheck %s
+; RUN: llc -mtriple=armv8 %s -o - | FileCheck %s
+
+; TODO: I think a post-incs should be possible here.
+
+; CHECK-LABEL: illegal_pre_inc_store_1
+; CHECK-NOT: str{{.*}} #8]!
+define i32* @illegal_pre_inc_store_1(i32* %base) {
+entry:
+  %ptr.to.use = getelementptr i32, i32* %base, i32 2
+  %ptr.to.store = ptrtoint i32* %base to i32
+  store i32 %ptr.to.store, i32* %ptr.to.use, align 4
+  ret i32* %ptr.to.use
+}
+
+; CHECK-LABEL: illegal_pre_inc_store_2
+; CHECK-NOT: str{{.*}} #8]!
+define i32* @illegal_pre_inc_store_2(i32* %base) {
+entry:
+  %ptr.to.use = getelementptr i32, i32* %base, i32 2
+  %ptr.to.store = ptrtoint i32* %ptr.to.use to i32
+  store i32 %ptr.to.store, i32* %ptr.to.use, align 4
+  ret i32* %ptr.to.use
+}