Index: lib/CodeGen/CGDecl.cpp
===================================================================
--- lib/CodeGen/CGDecl.cpp
+++ lib/CodeGen/CGDecl.cpp
@@ -969,12 +969,12 @@
   return llvm::isBytewiseValue(Init);
 }
 
-/// Decide whether we want to split a constant structure store into a sequence
-/// of its fields' stores. This may cost us code size and compilation speed,
-/// but plays better with store optimizations.
-static bool shouldSplitStructStore(CodeGenModule &CGM,
-                                   uint64_t GlobalByteSize) {
-  // Don't break structures that occupy more than one cacheline.
+/// Decide whether we want to split a constant structure or array store into a
+/// sequence of its fields' stores. This may cost us code size and compilation
+/// speed, but plays better with store optimizations.
+static bool shouldSplitConstantStore(CodeGenModule &CGM,
+                                     uint64_t GlobalByteSize) {
+  // Don't break things that occupy more than one cacheline.
   uint64_t ByteSizeLimit = 64;
   if (CGM.getCodeGenOpts().OptimizationLevel == 0)
     return false;
@@ -1202,9 +1202,9 @@
                                   CGBuilderTy &Builder,
                                   llvm::Constant *constant) {
   auto *Ty = constant->getType();
-  bool isScalar = Ty->isIntOrIntVectorTy() || Ty->isPtrOrPtrVectorTy() ||
-                  Ty->isFPOrFPVectorTy();
-  if (isScalar) {
+  bool canDoSingleStore = Ty->isIntOrIntVectorTy() ||
+                          Ty->isPtrOrPtrVectorTy() || Ty->isFPOrFPVectorTy();
+  if (canDoSingleStore) {
     Builder.CreateStore(constant, Loc, isVolatile);
     return;
   }
@@ -1212,12 +1212,13 @@
   auto *Int8Ty = llvm::IntegerType::getInt8Ty(CGM.getLLVMContext());
   auto *IntPtrTy = CGM.getDataLayout().getIntPtrType(CGM.getLLVMContext());
 
-  // If the initializer is all or mostly the same, codegen with bzero / memset
-  // then do a few stores afterward.
   uint64_t ConstantSize = CGM.getDataLayout().getTypeAllocSize(Ty);
   if (!ConstantSize)
     return;
   auto *SizeVal = llvm::ConstantInt::get(IntPtrTy, ConstantSize);
+
+  // If the initializer is all or mostly the same, codegen with bzero / memset
+  // then do a few stores afterward.
   if (shouldUseBZeroPlusStoresToInitialize(constant, ConstantSize)) {
     Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
                          isVolatile);
@@ -1231,6 +1232,7 @@
     return;
   }
 
+  // If the initializer is a repeated byte pattern, use memset.
   llvm::Value *Pattern = shouldUseMemSetToInitialize(constant, ConstantSize);
   if (Pattern) {
     uint64_t Value = 0x00;
@@ -1244,20 +1246,34 @@
     return;
   }
 
-  llvm::StructType *STy = dyn_cast<llvm::StructType>(Ty);
-  // FIXME: handle the case when STy != Loc.getElementType().
-  // FIXME: handle non-struct aggregate types.
-  if (STy && (STy == Loc.getElementType()) &&
-      shouldSplitStructStore(CGM, ConstantSize)) {
-    for (unsigned i = 0; i != constant->getNumOperands(); i++) {
-      Address EltPtr = Builder.CreateStructGEP(Loc, i);
-      emitStoresForConstant(
-          CGM, D, EltPtr, isVolatile, Builder,
-          cast<llvm::Constant>(Builder.CreateExtractValue(constant, i)));
+  // If the initializer is small, use a handful of stores.
+  if (shouldSplitConstantStore(CGM, ConstantSize)) {
+    if (auto *STy = dyn_cast<llvm::StructType>(Ty)) {
+      // FIXME: handle the case when STy != Loc.getElementType().
+      if (STy == Loc.getElementType()) {
+        for (unsigned i = 0; i != constant->getNumOperands(); i++) {
+          Address EltPtr = Builder.CreateStructGEP(Loc, i);
+          emitStoresForConstant(
+              CGM, D, EltPtr, isVolatile, Builder,
+              cast<llvm::Constant>(Builder.CreateExtractValue(constant, i)));
+        }
+        return;
+      }
+    } else if (auto *ATy = dyn_cast<llvm::ArrayType>(Ty)) {
+      // FIXME: handle the case when ATy != Loc.getElementType().
+      if (ATy == Loc.getElementType()) {
+        for (unsigned i = 0; i != ATy->getNumElements(); i++) {
+          Address EltPtr = Builder.CreateConstArrayGEP(Loc, i);
+          emitStoresForConstant(
+              CGM, D, EltPtr, isVolatile, Builder,
+              cast<llvm::Constant>(Builder.CreateExtractValue(constant, i)));
+        }
+        return;
+      }
     }
-    return;
   }
 
+  // Copy from a global.
   Builder.CreateMemCpy(
       Loc,
       createUnnamedGlobalFrom(CGM, D, Builder, constant, Loc.getAlignment()),
Index: test/CodeGenCXX/auto-var-init.cpp
===================================================================
--- test/CodeGenCXX/auto-var-init.cpp
+++ test/CodeGenCXX/auto-var-init.cpp
@@ -129,7 +129,6 @@
 // PATTERN-O1-NOT: @__const.test_bool4_custom.custom
 // ZERO-O1-NOT: @__const.test_bool4_custom.custom
 
-// PATTERN: @__const.test_intptr4_uninit.uninit = private unnamed_addr constant [4 x i32*] [i32* inttoptr (i64 -6148914691236517206 to i32*), i32* inttoptr (i64 -6148914691236517206 to i32*), i32* inttoptr (i64 -6148914691236517206 to i32*), i32* inttoptr (i64 -6148914691236517206 to i32*)], align 16
 // PATTERN: @__const.test_intptr4_custom.custom = private unnamed_addr constant [4 x i32*] [i32* inttoptr (i64 572662306 to i32*), i32* inttoptr (i64 572662306 to i32*), i32* inttoptr (i64 572662306 to i32*), i32* inttoptr (i64 572662306 to i32*)], align 16
 // ZERO: @__const.test_intptr4_custom.custom = private unnamed_addr constant [4 x i32*] [i32* inttoptr (i64 572662306 to i32*), i32* inttoptr (i64 572662306 to i32*), i32* inttoptr (i64 572662306 to i32*), i32* inttoptr (i64 572662306 to i32*)], align 16
 // PATTERN-O0: @__const.test_tailpad4_uninit.uninit = private unnamed_addr constant [4 x { i16, i8, [1 x i8] }] [{ i16, i8, [1 x i8] } { i16 -21846, i8 -86, [1 x i8] c"\AA" }, { i16, i8, [1 x i8] } { i16 -21846, i8 -86, [1 x i8] c"\AA" }, { i16, i8, [1 x i8] } { i16 -21846, i8 -86, [1 x i8] c"\AA" }, { i16, i8, [1 x i8] } { i16 -21846, i8 -86, [1 x i8] c"\AA" }], align 16
@@ -1019,13 +1018,20 @@
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%custom)
 
 TEST_UNINIT(intptr4, int*[4]);
-// CHECK-LABEL: @test_intptr4_uninit()
-// CHECK:       %uninit = alloca [4 x i32*], align
-// CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
+// CHECK-LABEL:   @test_intptr4_uninit()
+// CHECK:         %uninit = alloca [4 x i32*], align
+// CHECK-NEXT:    call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_intptr4_uninit()
-// PATTERN: call void @llvm.memcpy{{.*}} @__const.test_intptr4_uninit.uninit
-// ZERO-LABEL: @test_intptr4_uninit()
-// ZERO: call void @llvm.memset{{.*}}, i8 0,
+// PATTERN:       %1 = getelementptr inbounds [4 x i32*], [4 x i32*]* %uninit, i64 0, i64 0
+// PATTERN-NEXT:  store i32* inttoptr (i64 -6148914691236517206 to i32*), i32** %1, align 16
+// PATTERN-NEXT:  %2 = getelementptr inbounds [4 x i32*], [4 x i32*]* %uninit, i64 0, i64 1
+// PATTERN-NEXT:  store i32* inttoptr (i64 -6148914691236517206 to i32*), i32** %2, align 8
+// PATTERN-NEXT:  %3 = getelementptr inbounds [4 x i32*], [4 x i32*]* %uninit, i64 0, i64 2
+// PATTERN-NEXT:  store i32* inttoptr (i64 -6148914691236517206 to i32*), i32** %3, align 16
+// PATTERN-NEXT:  %4 = getelementptr inbounds [4 x i32*], [4 x i32*]* %uninit, i64 0, i64 3
+// PATTERN-NEXT:  store i32* inttoptr (i64 -6148914691236517206 to i32*), i32** %4, align 8
+// ZERO-LABEL:    @test_intptr4_uninit()
+// ZERO: call     void @llvm.memset{{.*}}, i8 0,
 
 TEST_BRACES(intptr4, int*[4]);
 // CHECK-LABEL: @test_intptr4_braces()
@@ -1124,7 +1130,7 @@
 // PATTERN-LABEL: @test_atomicnotlockfree_uninit()
 // PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_atomicnotlockfree_uninit.uninit
 // PATTERN-O1: bitcast
-// PATTERN-O1: call void @llvm.memset{{.*}}({{.*}}0, i8 -86, i64 32
+// PATTERN-O1: call void @llvm.memset{{.*}}({{.*}}, i8 -86, i64 32
 // ZERO-LABEL: @test_atomicnotlockfree_uninit()
 // ZERO: call void @llvm.memset{{.*}}, i8 0,