diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -954,19 +954,8 @@
   llvm::MostFrequentByte MFB =
       llvm::getMostFrequentByte(Init, CGM.getDataLayout());
 
-  if (0) {
-    // TODO: Use this branch and remove 'else'. Now we can do that for any
-    // value, but it requires tests updates, so I'll enable it in a separate
-    // patch.
-    if (MFB.Value && !MFB.Other)
-      return MFB.Value;
-  } else {
-    if (isa<llvm::ConstantAggregateZero>(Init)) {
-      assert(MFB.Value);
-      assert(!MFB.Other);
-      return MFB.Value;
-    }
-  }
+  if (MFB.Value && !MFB.Other)
+    return MFB.Value;
 
   // TODO: Tweak these constants or use "density".
   uint64_t SizeLimit = 32;
diff --git a/clang/test/CodeGen/arm-swiftcall.c b/clang/test/CodeGen/arm-swiftcall.c
--- a/clang/test/CodeGen/arm-swiftcall.c
+++ b/clang/test/CodeGen/arm-swiftcall.c
@@ -168,7 +168,7 @@
 TEST(struct_2);
 // CHECK-LABEL: define {{.*}} @return_struct_2()
 // CHECK:   [[RET:%.*]] = alloca [[REC:%.*]], align 4
-// CHECK:   @llvm.memcpy
+// CHECK:   @llvm.memset
 // CHECK:   [[CAST_TMP:%.*]] = bitcast [[REC]]* [[RET]] to [[AGG:{ i32, i32, float, float }]]*
 // CHECK:   [[T0:%.*]] = getelementptr inbounds [[AGG]], [[AGG]]* [[CAST_TMP]], i32 0, i32 0
 // CHECK:   [[FIRST:%.*]] = load i32, i32* [[T0]], align 4
@@ -276,7 +276,7 @@
 TEST(union_het_fp)
 // CHECK-LABEL: define {{.*}} @return_union_het_fp()
 // CHECK:   [[RET:%.*]] = alloca [[REC:%.*]], align {{(4|8)}}
-// CHECK:   @llvm.memcpy
+// CHECK:   @llvm.memset
 // CHECK:   [[CAST_TMP:%.*]] = bitcast [[REC]]* [[RET]] to [[AGG:{ i32, i32 }]]*
 // CHECK:   [[T0:%.*]] = getelementptr inbounds [[AGG]], [[AGG]]* [[CAST_TMP]], i32 0, i32 0
 // CHECK:   [[FIRST:%.*]] = load i32, i32* [[T0]], align {{(4|8)}}
@@ -311,7 +311,6 @@
 // CHECK:   call [[SWIFTCC]] void @take_union_het_fp(i32 [[FIRST]], i32 [[SECOND]])
 // CHECK:   ret void
 
-
 typedef union {
   float f1;
   float f2;
diff --git a/clang/test/CodeGen/dump-struct-builtin.c b/clang/test/CodeGen/dump-struct-builtin.c
--- a/clang/test/CodeGen/dump-struct-builtin.c
+++ b/clang/test/CodeGen/dump-struct-builtin.c
@@ -51,7 +51,6 @@
 // CHECK-NEXT: [[FORMAT_U8:@[0-9]+]] = private unnamed_addr constant [6 x i8] c"%llu\0A\00"
 // CHECK-NEXT: [[END_STRUCT_U8:@[0-9]+]] = private unnamed_addr constant [3 x i8] c"}\0A\00"
 
-// CHECK: @__const.unit9.a = private unnamed_addr constant %struct.U9A { i8 97 }, align 1
 // CHECK-NEXT: [[STRUCT_STR_U9:@[0-9]+]] = private unnamed_addr constant [14 x i8] c"struct U9A {\0A\00"
 // CHECK-NEXT: [[FIELD_U9:@[0-9]+]] = private unnamed_addr constant [10 x i8] c"char a : \00"
 // CHECK-NEXT: [[FORMAT_U9:@[0-9]+]] = private unnamed_addr constant [4 x i8] c"%c\0A\00"
@@ -95,13 +94,11 @@
 // CHECK-NEXT: [[FORMAT_U15:@[0-9]+]] = private unnamed_addr constant [4 x i8] c"%p\0A\00"
 // CHECK-NEXT: [[END_STRUCT_U15:@[0-9]+]] = private unnamed_addr constant [3 x i8] c"}\0A\00"
 
-// CHECK: @__const.unit16.a = private unnamed_addr constant %struct.U16A { i8 12 }, align 1
 // CHECK-NEXT: [[STRUCT_STR_U16:@[0-9]+]] = private unnamed_addr constant [15 x i8] c"struct U16A {\0A\00"
 // CHECK-NEXT: [[FIELD_U16:@[0-9]+]] = private unnamed_addr constant [13 x i8] c"uint8_t a : \00"
 // CHECK-NEXT: [[FORMAT_U16:@[0-9]+]] = private unnamed_addr constant [6 x i8] c"%hhu\0A\00"
 // CHECK-NEXT: [[END_STRUCT_U16:@[0-9]+]] = private unnamed_addr constant [3 x i8] c"}\0A\00"
 
-// CHECK: @__const.unit17.a = private unnamed_addr constant %struct.U17A { i8 12 }, align 1
 // CHECK-NEXT: [[STRUCT_STR_U17:@[0-9]+]] = private unnamed_addr constant [15 x i8] c"struct U17A {\0A\00"
 // CHECK-NEXT: [[FIELD_U17:@[0-9]+]] = private unnamed_addr constant [12 x i8] c"int8_t a : \00"
 // CHECK-NEXT: [[FORMAT_U17:@[0-9]+]] = private unnamed_addr constant [6 x i8] c"%hhd\0A\00"
diff --git a/clang/test/CodeGen/init-memset.c b/clang/test/CodeGen/init-memset.c
--- a/clang/test/CodeGen/init-memset.c
+++ b/clang/test/CodeGen/init-memset.c
@@ -12,7 +12,7 @@
 void test_small_same() {
   // CHECK-LABEL: define void @test_small_same()
   char a[] = {'a', 'a', 'a', 'a'};
-  // CHECK: call void @llvm.memcpy.{{.*}}
+  // CHECK: call void @llvm.memset.{{.*}}
   use(a);
 }
 
diff --git a/clang/test/CodeGen/windows-swiftcall.c b/clang/test/CodeGen/windows-swiftcall.c
--- a/clang/test/CodeGen/windows-swiftcall.c
+++ b/clang/test/CodeGen/windows-swiftcall.c
@@ -5,8 +5,6 @@
 #define ERROR __attribute__((swift_error_result))
 #define CONTEXT __attribute__((swift_context))
 
-// CHECK: [[STRUCT2_RESULT:@.*]] = private {{.*}} constant [[STRUCT2_TYPE:%.*]] { i32 0, i8 0, i8 undef, i8 0, i32 0, i32 0 }
-
 /*****************************************************************************/
 /****************************** PARAMETER ABIS *******************************/
 /*****************************************************************************/
@@ -146,9 +144,9 @@
 } struct_2;
 TEST(struct_2);
 // CHECK-LABEL: define dso_local swiftcc { i64, i64 } @return_struct_2() {{.*}}{
-// CHECK:   [[RET:%.*]] = alloca [[STRUCT2_TYPE]], align 4
+// CHECK:   [[RET:%.*]] = alloca [[STRUCT2_TYPE:%.*]], align 4
 // CHECK:   [[CASTVAR:%.*]] = bitcast {{.*}} [[RET]]
-// CHECK:   call void @llvm.memcpy{{.*}}({{.*}}[[CASTVAR]], {{.*}}[[STRUCT2_RESULT]]
+// CHECK:   call void @llvm.memset{{.*}}({{.*}}[[CASTVAR]], {{.*}}
 // CHECK:   [[CAST:%.*]] = bitcast [[STRUCT2_TYPE]]* [[RET]] to { i64, i64 }*
 // CHECK:   [[GEP0:%.*]] = getelementptr inbounds { i64, i64 }, { i64, i64 }* [[CAST]], i32 0, i32 0
 // CHECK:   [[T0:%.*]] = load i64, i64* [[GEP0]], align 4
@@ -249,7 +247,7 @@
 // CHECK-LABEL: define dso_local swiftcc i64 @return_union_het_fp()
 // CHECK:  [[RET:%.*]] = alloca [[UNION:%.*]], align 8
 // CHECK:  [[CAST:%.*]] = bitcast [[UNION]]* [[RET]] to i8*
-// CHECK:  call void @llvm.memcpy{{.*}}(i8* align {{[0-9]+}} [[CAST]]
+// CHECK:  call void @llvm.memset{{.*}}(i8* align {{[0-9]+}} [[CAST]]
 // CHECK:  [[CAST:%.*]] = bitcast [[UNION]]* [[RET]] to { i64 }*
 // CHECK:  [[GEP:%.*]] = getelementptr inbounds { i64 }, { i64 }* [[CAST]], i32 0, i32 0
 // CHECK:  [[R0:%.*]] = load i64, i64* [[GEP]], align 8
@@ -274,7 +272,6 @@
 // CHECK:   ret void
 // CHECK: }
 
-
 typedef union {
   float f1;
   float f2;
diff --git a/clang/test/CodeGenCXX/auto-var-init.cpp b/clang/test/CodeGenCXX/auto-var-init.cpp
--- a/clang/test/CodeGenCXX/auto-var-init.cpp
+++ b/clang/test/CodeGenCXX/auto-var-init.cpp
@@ -34,193 +34,64 @@
 // PATTERN-NOT: undef
 // ZERO-NOT: undef
 
-// PATTERN-O0: @__const.test_empty_uninit.uninit = private unnamed_addr constant %struct.empty { i8 -86 }, align 1
-// PATTERN-O1-NOT: @__const.test_empty_uninit.uninit
 struct empty {};
-// PATTERN-O0: @__const.test_small_uninit.uninit = private unnamed_addr constant %struct.small { i8 -86 }, align 1
-// PATTERN-O0: @__const.test_small_custom.custom = private unnamed_addr constant %struct.small { i8 42 }, align 1
-// ZERO-O0: @__const.test_small_custom.custom = private unnamed_addr constant %struct.small { i8 42 }, align 1
-// PATTERN-O1-NOT: @__const.test_small_uninit.uninit
-// PATTERN-O1-NOT: @__const.test_small_custom.custom
-// ZERO-O1-NOT: @__const.test_small_custom.custom
 struct small { char c; };
-// PATTERN-O0: @__const.test_smallinit_uninit.uninit = private unnamed_addr constant %struct.smallinit { i8 -86 }, align 1
-// PATTERN-O0: @__const.test_smallinit_braces.braces = private unnamed_addr constant %struct.smallinit { i8 -86 }, align 1
-// PATTERN-O0: @__const.test_smallinit_custom.custom = private unnamed_addr constant %struct.smallinit { i8 -86 }, align 1
-// PATTERN-O1-NOT: @__const.test_smallinit_uninit.uninit
-// PATTERN-O1-NOT: @__const.test_smallinit_braces.braces
-// PATTERN-O1-NOT: @__const.test_smallinit_custom.custom
 struct smallinit { char c = 42; };
-// PATTERN-O0: @__const.test_smallpartinit_uninit.uninit = private unnamed_addr constant %struct.smallpartinit { i8 -86, i8 -86 }, align 1
-// PATTERN-O0: @__const.test_smallpartinit_braces.braces = private unnamed_addr constant %struct.smallpartinit { i8 -86, i8 -86 }, align 1
-// PATTERN-O0: @__const.test_smallpartinit_custom.custom = private unnamed_addr constant %struct.smallpartinit { i8 -86, i8 -86 }, align 1
-// PATTERN-O1-NOT: @__const.test_smallpartinit_uninit.uninit
-// PATTERN-O1-NOT: @__const.test_smallpartinit_braces.braces
-// PATTERN-O1-NOT: @__const.test_smallpartinit_custom.custom
 struct smallpartinit { char c = 42, d; };
-// PATTERN-O0: @__const.test_nullinit_uninit.uninit = private unnamed_addr constant %struct.nullinit { i8* inttoptr (i64 -6148914691236517206 to i8*) }, align 8
-// PATTERN-O0: @__const.test_nullinit_braces.braces = private unnamed_addr constant %struct.nullinit { i8* inttoptr (i64 -6148914691236517206 to i8*) }, align 8
-// PATTERN-O0: @__const.test_nullinit_custom.custom = private unnamed_addr constant %struct.nullinit { i8* inttoptr (i64 -6148914691236517206 to i8*) }, align 8
-// PATTERN-O1-NOT: @__const.test_nullinit_uninit.uninit
-// PATTERN-O1-NOT: @__const.test_nullinit_braces.braces
-// PATTERN-O1-NOT: @__const.test_nullinit_custom.custom
 struct nullinit { char* null = nullptr; };
-// PATTERN-O0: @__const.test_padded_uninit.uninit = private unnamed_addr constant { i8, [3 x i8], i32 } { i8 -86, [3 x i8] c"\AA\AA\AA", i32 -1431655766 }, align 4
 // PATTERN-O0: @__const.test_padded_custom.custom = private unnamed_addr constant { i8, [3 x i8], i32 } { i8 42, [3 x i8] zeroinitializer, i32 13371337 }, align 4
 // ZERO-O0: @__const.test_padded_custom.custom = private unnamed_addr constant { i8, [3 x i8], i32 } { i8 42, [3 x i8] zeroinitializer, i32 13371337 }, align 4
-// PATTERN-O1-NOT: @__const.test_padded_uninit.uninit
-// PATTERN-O1-NOT: @__const.test_padded_custom.custom
-// ZERO-O1-NOT: @__const.test_padded_custom.custom
 struct padded { char c; int i; };
-// PATTERN-O0: @__const.test_paddednullinit_uninit.uninit = private unnamed_addr constant { i8, [3 x i8], i32 } { i8 -86, [3 x i8] c"\AA\AA\AA", i32 -1431655766 }, align 4
-// PATTERN-O0: @__const.test_paddednullinit_braces.braces = private unnamed_addr constant { i8, [3 x i8], i32 } { i8 -86, [3 x i8] c"\AA\AA\AA", i32 -1431655766 }, align 4
-// PATTERN-O0: @__const.test_paddednullinit_custom.custom = private unnamed_addr constant { i8, [3 x i8], i32 } { i8 -86, [3 x i8] c"\AA\AA\AA", i32 -1431655766 }, align 4
-// PATTERN-O1-NOT: @__const.test_paddednullinit_uninit.uninit
-// PATTERN-O1-NOT: @__const.test_paddednullinit_braces.braces
-// PATTERN-O1-NOT: @__const.test_paddednullinit_custom.custom
 struct paddednullinit { char c = 0; int i = 0; };
-// PATTERN-O0: @__const.test_paddedpacked_uninit.uninit = private unnamed_addr constant %struct.paddedpacked <{ i8 -86, i32 -1431655766 }>, align 1
 // PATTERN: @__const.test_paddedpacked_custom.custom = private unnamed_addr constant %struct.paddedpacked <{ i8 42, i32 13371337 }>, align 1
 // ZERO: @__const.test_paddedpacked_custom.custom = private unnamed_addr constant %struct.paddedpacked <{ i8 42, i32 13371337 }>, align 1
 struct paddedpacked { char c; int i; } __attribute__((packed));
-// PATTERN-O0: @__const.test_paddedpackedarray_uninit.uninit = private unnamed_addr constant %struct.paddedpackedarray { [2 x %struct.paddedpacked] [%struct.paddedpacked <{ i8 -86, i32 -1431655766 }>, %struct.paddedpacked <{ i8 -86, i32 -1431655766 }>] }, align 1
 // PATTERN: @__const.test_paddedpackedarray_custom.custom = private unnamed_addr constant %struct.paddedpackedarray { [2 x %struct.paddedpacked] [%struct.paddedpacked <{ i8 42, i32 13371337 }>, %struct.paddedpacked <{ i8 43, i32 13371338 }>] }, align 1
 // ZERO: @__const.test_paddedpackedarray_custom.custom = private unnamed_addr constant %struct.paddedpackedarray { [2 x %struct.paddedpacked] [%struct.paddedpacked <{ i8 42, i32 13371337 }>, %struct.paddedpacked <{ i8 43, i32 13371338 }>] }, align 1
 struct paddedpackedarray { struct paddedpacked p[2]; };
-// PATTERN-O0: @__const.test_unpackedinpacked_uninit.uninit = private unnamed_addr constant <{ { i8, [3 x i8], i32 }, i8 }> <{ { i8, [3 x i8], i32 } { i8 -86, [3 x i8] c"\AA\AA\AA", i32 -1431655766 }, i8 -86 }>, align 1
 struct unpackedinpacked { padded a; char b; } __attribute__((packed));
-// PATTERN-O0: @__const.test_paddednested_uninit.uninit = private unnamed_addr constant { { i8, [3 x i8], i32 }, { i8, [3 x i8], i32 } } { { i8, [3 x i8], i32 } { i8 -86, [3 x i8] c"\AA\AA\AA", i32 -1431655766 }, { i8, [3 x i8], i32 } { i8 -86, [3 x i8] c"\AA\AA\AA", i32 -1431655766 } }, align 4
 // PATTERN: @__const.test_paddednested_custom.custom = private unnamed_addr constant { { i8, [3 x i8], i32 }, { i8, [3 x i8], i32 } } { { i8, [3 x i8], i32 } { i8 42, [3 x i8] zeroinitializer, i32 13371337 }, { i8, [3 x i8], i32 } { i8 43, [3 x i8] zeroinitializer, i32 13371338 } }, align 4
 // ZERO: @__const.test_paddednested_custom.custom = private unnamed_addr constant { { i8, [3 x i8], i32 }, { i8, [3 x i8], i32 } } { { i8, [3 x i8], i32 } { i8 42, [3 x i8] zeroinitializer, i32 13371337 }, { i8, [3 x i8], i32 } { i8 43, [3 x i8] zeroinitializer, i32 13371338 } }, align 4
 struct paddednested { struct padded p1, p2; };
-// PATTERN-O0: @__const.test_paddedpackednested_uninit.uninit = private unnamed_addr constant %struct.paddedpackednested { %struct.paddedpacked <{ i8 -86, i32 -1431655766 }>, %struct.paddedpacked <{ i8 -86, i32 -1431655766 }> }, align 1
 // PATTERN: @__const.test_paddedpackednested_custom.custom = private unnamed_addr constant %struct.paddedpackednested { %struct.paddedpacked <{ i8 42, i32 13371337 }>, %struct.paddedpacked <{ i8 43, i32 13371338 }> }, align 1
 // ZERO: @__const.test_paddedpackednested_custom.custom = private unnamed_addr constant %struct.paddedpackednested { %struct.paddedpacked <{ i8 42, i32 13371337 }>, %struct.paddedpacked <{ i8 43, i32 13371338 }> }, align 1
 struct paddedpackednested { struct paddedpacked p1, p2; };
-// PATTERN-O0: @__const.test_bitfield_uninit.uninit = private unnamed_addr constant %struct.bitfield { i8 -86, [3 x i8] c"\AA\AA\AA" }, align 4
 // PATTERN-O0: @__const.test_bitfield_custom.custom = private unnamed_addr constant %struct.bitfield { i8 20, [3 x i8] c"\AA\AA\AA" }, align 4
 // ZERO-O0: @__const.test_bitfield_custom.custom = private unnamed_addr constant %struct.bitfield { i8 20, [3 x i8] zeroinitializer }, align 4
-// PATTERN-O1-NOT: @__const.test_bitfield_uninit.uninit
-// PATTERN-O1-NOT: @__const.test_bitfield_custom.custom
-// ZERO-O1-NOT: @__const.test_bitfield_custom.custom
 struct bitfield { int i : 4; int j : 2; };
-// PATTERN-O0: @__const.test_bitfieldaligned_uninit.uninit = private unnamed_addr constant %struct.bitfieldaligned { i8 -86, [3 x i8] c"\AA\AA\AA", i8 -86, [3 x i8] c"\AA\AA\AA" }, align 4
 // PATTERN-O0: @__const.test_bitfieldaligned_custom.custom = private unnamed_addr constant %struct.bitfieldaligned { i8 4, [3 x i8] c"\AA\AA\AA", i8 1, [3 x i8] c"\AA\AA\AA" }, align 4
 // ZERO-O0: @__const.test_bitfieldaligned_custom.custom = private unnamed_addr constant %struct.bitfieldaligned { i8 4, [3 x i8] zeroinitializer, i8 1, [3 x i8] zeroinitializer }, align 4
-// PATTERN-O1-NOT: @__const.test_bitfieldaligned_uninit.uninit
-// PATTERN-O1-NOT: @__const.test_bitfieldaligned_custom.custom
-// ZERO-O1-NOT: @__const.test_bitfieldaligned_custom.custom
 struct bitfieldaligned { int i : 4; int : 0; int j : 2; };
 struct big { unsigned a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z; };
-// PATTERN-O0: @__const.test_arraytail_uninit.uninit = private unnamed_addr constant %struct.arraytail { i32 -1431655766, [0 x i32] zeroinitializer }, align 4
 // PATTERN-O0: @__const.test_arraytail_custom.custom = private unnamed_addr constant %struct.arraytail { i32 57005, [0 x i32] zeroinitializer }, align 4
 // ZERO-O0: @__const.test_arraytail_custom.custom = private unnamed_addr constant %struct.arraytail { i32 57005, [0 x i32] zeroinitializer }, align 4
-// PATTERN-O1-NOT: @__const.test_arraytail_uninit.uninit
-// PATTERN-O1-NOT: @__const.test_arraytail_custom.custom
-// ZERO-O1-NOT: @__const.test_arraytail_custom.custom
 struct arraytail { int i; int arr[]; };
-// PATTERN-O0: @__const.test_int1_uninit.uninit = private unnamed_addr constant [1 x i32] [i32 -1431655766], align 4
-// PATTERN-O0: @__const.test_int1_custom.custom = private unnamed_addr constant [1 x i32] [i32 858993459], align 4
-// ZERO-O0: @__const.test_int1_custom.custom = private unnamed_addr constant [1 x i32] [i32 858993459], align 4
-// PATTERN-O1-NOT: @__const.test_int1_uninit.uninit
-// PATTERN-O1-NOT: @__const.test_int1_custom.custom
-// ZERO-O1-NOT: @__const.test_int1_custom.custom
-
-// PATTERN-O0: @__const.test_bool4_uninit.uninit = private unnamed_addr constant [4 x i8] c"\AA\AA\AA\AA", align 1
-// PATTERN-O0: @__const.test_bool4_custom.custom = private unnamed_addr constant [4 x i8] c"\01\01\01\01", align 1
-// ZERO-O0: @__const.test_bool4_custom.custom = private unnamed_addr constant [4 x i8] c"\01\01\01\01", align 1
-// PATTERN-O1-NOT: @__const.test_bool4_uninit.uninit
-// PATTERN-O1-NOT: @__const.test_bool4_custom.custom
-// ZERO-O1-NOT: @__const.test_bool4_custom.custom
 
 // 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
-// PATTERN-O1-NOT: @__const.test_tailpad4_uninit.uninit
 // PATTERN: @__const.test_tailpad4_custom.custom = private unnamed_addr constant [4 x { i16, i8, [1 x i8] }] [{ i16, i8, [1 x i8] } { i16 257, i8 1, [1 x i8] zeroinitializer }, { i16, i8, [1 x i8] } { i16 257, i8 1, [1 x i8] zeroinitializer }, { i16, i8, [1 x i8] } { i16 257, i8 1, [1 x i8] zeroinitializer }, { i16, i8, [1 x i8] } { i16 257, i8 1, [1 x i8] zeroinitializer }], align 16
 // ZERO: @__const.test_tailpad4_custom.custom = private unnamed_addr constant [4 x { i16, i8, [1 x i8] }] [{ i16, i8, [1 x i8] } { i16 257, i8 1, [1 x i8] zeroinitializer }, { i16, i8, [1 x i8] } { i16 257, i8 1, [1 x i8] zeroinitializer }, { i16, i8, [1 x i8] } { i16 257, i8 1, [1 x i8] zeroinitializer }, { i16, i8, [1 x i8] } { i16 257, i8 1, [1 x i8] zeroinitializer }], align 16
 struct tailpad { short s; char c; };
-// PATTERN-O0: @__const.test_atomicnotlockfree_uninit.uninit = private unnamed_addr constant %struct.notlockfree { [4 x i64] [i64 -6148914691236517206, i64 -6148914691236517206, i64 -6148914691236517206, i64 -6148914691236517206] }, align 8
-// PATTERN-O1-NOT: @__const.test_atomicnotlockfree_uninit.uninit
 struct notlockfree { long long a[4]; };
-// PATTERN-O0: @__const.test_atomicpadded_uninit.uninit = private unnamed_addr constant { i8, [3 x i8], i32 } { i8 -86, [3 x i8] c"\AA\AA\AA", i32 -1431655766 }, align 8
-// PATTERN-O1-NOT: @__const.test_atomicpadded_uninit.uninit
-// PATTERN-O0: @__const.test_atomictailpad_uninit.uninit = private unnamed_addr constant { i16, i8, [1 x i8] } { i16 -21846, i8 -86, [1 x i8] c"\AA" }, align 4
-// PATTERN-O1-NOT: @__const.test_atomictailpad_uninit.uninit
-// PATTERN-O0: @__const.test_complexfloat_uninit.uninit = private unnamed_addr constant { float, float } { float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000 }, align 4
-// PATTERN-O1-NOT: @__const.test_complexfloat_uninit.uninit
-// PATTERN-O0: @__const.test_complexfloat_braces.braces = private unnamed_addr constant { float, float } { float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000 }, align 4
-// PATTERN-O1-NOT: @__const.test_complexfloat_braces.braces
-// PATTERN-O0: @__const.test_complexfloat_custom.custom = private unnamed_addr constant { float, float } { float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000 }, align 4
-// PATTERN-O1-NOT: @__const.test_complexfloat_custom.custom
-// PATTERN-O0: @__const.test_complexdouble_uninit.uninit = private unnamed_addr constant { double, double } { double 0xFFFFFFFFFFFFFFFF, double 0xFFFFFFFFFFFFFFFF }, align 8
-// PATTERN-O1-NOT: @__const.test_complexdouble_uninit.uninit
-// PATTERN-O0: @__const.test_complexdouble_braces.braces = private unnamed_addr constant { double, double } { double 0xFFFFFFFFFFFFFFFF, double 0xFFFFFFFFFFFFFFFF }, align 8
-// PATTERN-O1-NOT: @__const.test_complexdouble_braces.braces
-// PATTERN-O0: @__const.test_complexdouble_custom.custom = private unnamed_addr constant { double, double } { double 0xFFFFFFFFFFFFFFFF, double 0xFFFFFFFFFFFFFFFF }, align 8
-// PATTERN-O1-NOT: @__const.test_complexdouble_custom.custom
-// PATTERN-O0: @__const.test_semivolatile_uninit.uninit = private unnamed_addr constant %struct.semivolatile { i32 -1431655766, i32 -1431655766 }, align 4
-// PATTERN-O0: @__const.test_semivolatile_custom.custom = private unnamed_addr constant %struct.semivolatile { i32 1145324612, i32 1145324612 }, align 4
-// PATTERN-O1-NOT: @__const.test_semivolatile_custom.custom
 struct semivolatile { int i; volatile int vi; };
-// PATTERN-O0: @__const.test_semivolatileinit_uninit.uninit = private unnamed_addr constant %struct.semivolatileinit { i32 -1431655766, i32 -1431655766 }, align 4
-// PATTERN-O1-NOT: @__const.test_semivolatileinit_uninit.uninit
-// PATTERN-O0: @__const.test_semivolatileinit_braces.braces = private unnamed_addr constant %struct.semivolatileinit { i32 -1431655766, i32 -1431655766 }, align 4
-// PATTERN-O1-NOT: @__const.test_semivolatileinit_braces.braces
-// PATTERN-O0: @__const.test_semivolatileinit_custom.custom = private unnamed_addr constant %struct.semivolatileinit { i32 -1431655766, i32 -1431655766 }, align 4
-// PATTERN-O1-NOT: @__const.test_semivolatileinit_custom.custom = private unnamed_addr constant %struct.semivolatileinit { i32 -1431655766, i32 -1431655766 }, align 4
-// ZERO-O0: @__const.test_semivolatile_custom.custom = private unnamed_addr constant %struct.semivolatile { i32 1145324612, i32 1145324612 }, align 4
-// ZERO-O1-NOT: @__const.test_semivolatile_custom.custom
 struct semivolatileinit { int i = 0x11111111; volatile int vi = 0x11111111; };
-// PATTERN-O0: @__const.test_base_uninit.uninit = private unnamed_addr constant %struct.base { i32 (...)** inttoptr (i64 -6148914691236517206 to i32 (...)**) }, align 8
-// PATTERN-O1-NOT: @__const.test_base_uninit.uninit
-// PATTERN-O0: @__const.test_base_braces.braces = private unnamed_addr constant %struct.base { i32 (...)** inttoptr (i64 -6148914691236517206 to i32 (...)**) }, align 8
-// PATTERN-O1-NOT: @__const.test_base_braces.braces
 struct base { virtual ~base(); };
-// PATTERN-O0: @__const.test_derived_uninit.uninit = private unnamed_addr constant %struct.derived { %struct.base { i32 (...)** inttoptr (i64 -6148914691236517206 to i32 (...)**) } }, align 8
-// PATTERN-O1-NOT: @__const.test_derived_uninit.uninit
-// PATTERN-O0: @__const.test_derived_braces.braces = private unnamed_addr constant %struct.derived { %struct.base { i32 (...)** inttoptr (i64 -6148914691236517206 to i32 (...)**) } }, align 8
-// PATTERN-O1-NOT: @__const.test_derived_braces.braces
 struct derived : public base {};
-// PATTERN-O0: @__const.test_virtualderived_uninit.uninit = private unnamed_addr constant %struct.virtualderived { %struct.base { i32 (...)** inttoptr (i64 -6148914691236517206 to i32 (...)**) }, %struct.derived { %struct.base { i32 (...)** inttoptr (i64 -6148914691236517206 to i32 (...)**) } } }, align 8
-// PATTERN-O1-NOT: @__const.test_virtualderived_uninit.uninit
-// PATTERN-O0: @__const.test_virtualderived_braces.braces = private unnamed_addr constant %struct.virtualderived { %struct.base { i32 (...)** inttoptr (i64 -6148914691236517206 to i32 (...)**) }, %struct.derived { %struct.base { i32 (...)** inttoptr (i64 -6148914691236517206 to i32 (...)**) } } }, align 8
-// PATTERN-O1-NOT: @__const.test_virtualderived_braces.braces
 struct virtualderived : public virtual base, public virtual derived {};
-// PATTERN-O0: @__const.test_matching_uninit.uninit = private unnamed_addr constant %union.matching { i32 -1431655766 }, align 4
-// PATTERN-O1-NOT: @__const.test_matching_uninit.uninit
 // PATTERN-O0: @__const.test_matching_custom.custom = private unnamed_addr constant { float } { float 6.145500e+04 }, align 4
-// PATTERN-O1-NOT: @__const.test_matching_custom.custom
 // ZERO-O0: @__const.test_matching_custom.custom = private unnamed_addr constant { float } { float 6.145500e+04 }, align 4
-// ZERO-O1-NOT: @__const.test_matching_custom.custom
 union matching { int i; float f; };
-// PATTERN-O0: @__const.test_matchingreverse_uninit.uninit = private unnamed_addr constant %union.matchingreverse { float 0xFFFFFFFFE0000000 }, align 4
-// PATTERN-O1-NOT: @__const.test_matchingreverse_uninit.uninit
 // PATTERN-O0: @__const.test_matchingreverse_custom.custom = private unnamed_addr constant { i32 } { i32 61455 }, align 4
-// PATTERN-O1-NOT: @__const.test_matchingreverse_custom.custom
 // ZERO-O0: @__const.test_matchingreverse_custom.custom = private unnamed_addr constant { i32 } { i32 61455 }, align 4
-// ZERO-O1-NOT: @__const.test_matchingreverse_custom.custom
 union matchingreverse { float f; int i; };
-// PATTERN-O0: @__const.test_unmatched_uninit.uninit = private unnamed_addr constant %union.unmatched { i32 -1431655766 }, align 4
-// PATTERN-O1-NOT: @__const.test_unmatched_uninit.uninit
 // PATTERN-O0: @__const.test_unmatched_custom.custom = private unnamed_addr constant %union.unmatched { i32 1001242351 }, align 4
-// PATTERN-O1-NOT: @__const.test_unmatched_custom.custom
 // ZERO-O0: @__const.test_unmatched_custom.custom = private unnamed_addr constant %union.unmatched { i32 1001242351 }, align 4
-// ZERO-O1-NOT: @__const.test_unmatched_custom.custom
 union unmatched { char c; int i; };
-// PATTERN-O0: @__const.test_unmatchedreverse_uninit.uninit = private unnamed_addr constant %union.unmatchedreverse { i32 -1431655766 }, align 4
-// PATTERN-O1-NOT: @__const.test_unmatchedreverse_uninit.uninit
 // PATTERN-O0: @__const.test_unmatchedreverse_custom.custom = private unnamed_addr constant { i8, [3 x i8] } { i8 42, [3 x i8] c"\AA\AA\AA" }, align 4
-// PATTERN-O1-NOT: @__const.test_unmatchedreverse_custom.custom
 // ZERO-O0: @__const.test_unmatchedreverse_custom.custom = private unnamed_addr constant { i8, [3 x i8] } { i8 42, [3 x i8] zeroinitializer }, align 4
-// ZERO-O1-NOT: @__const.test_unmatchedreverse_custom.custom
 union unmatchedreverse { int i; char c; };
-// PATTERN-O0: @__const.test_unmatchedfp_uninit.uninit = private unnamed_addr constant %union.unmatchedfp { double 0xFFFFFFFFFFFFFFFF }, align 8
-// PATTERN-O1-NOT: @__const.test_unmatchedfp_uninit.uninit
 // PATTERN-O0: @__const.test_unmatchedfp_custom.custom = private unnamed_addr constant %union.unmatchedfp { double 0x400921FB54442D18 }, align 8
-// PATTERN-O1-NOT: @__const.test_unmatchedfp_custom.custom
 // ZERO-O0: @__const.test_unmatchedfp_custom.custom = private unnamed_addr constant %union.unmatchedfp { double 0x400921FB54442D18 }, align 8
-// ZERO-O1-NOT: @__const.test_unmatchedfp_custom.custom
 union unmatchedfp { float f; double d; };
 enum emptyenum {};
 enum smallenum { VALUE };
@@ -565,7 +436,7 @@
 // CHECK:       %uninit = alloca %struct.empty, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_empty_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_empty_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 1, i1 false)
 // PATTERN-O1: store i8 -86, {{.*}} align 1
 // ZERO-LABEL: @test_empty_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
@@ -575,7 +446,7 @@
 // CHECK-LABEL: @test_empty_braces()
 // CHECK:       %braces = alloca %struct.empty, align
 // CHECK-NEXT:  bitcast
-// CHECK-NEXT:  call void @llvm.memcpy
+// CHECK1-NEXT:  call void @llvm.memcpy
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%braces)
 
 TEST_UNINIT(small, small);
@@ -583,7 +454,7 @@
 // CHECK:       %uninit = alloca %struct.small, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_small_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_small_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 1, i1 false)
 // PATTERN-O1: store i8 -86, {{.*}} align 1
 // ZERO-LABEL: @test_small_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
@@ -600,7 +471,7 @@
 // CHECK-LABEL: @test_small_custom()
 // CHECK:       %custom = alloca %struct.small, align
 // CHECK-NEXT:  bitcast
-// CHECK-NEXT:  call void @llvm.memcpy
+// CHECK-NEXT:  call void @llvm.memset
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%custom)
 
 TEST_UNINIT(smallinit, smallinit);
@@ -629,9 +500,10 @@
 // CHECK-NEXT:  call void @{{.*}}smallpartinit{{.*}}%uninit)
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_smallpartinit_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_smallpartinit_uninit.uninit
-// PATTERN-O1: store i8 -86, {{.*}} align 1
-// PATTERN-O1: store i8 42, {{.*}} align 1
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 2, i1 false)
+// PATTERN-O1-LEGACY: store i16 -21846, {{.*}} align 2
+// PATTERN-O1-LEGACY: call void @_ZN13smallpartinitC1Ev
+// PATTERN-O1-NEWPM: store i16 -21974, {{.*}} align 2
 // ZERO-LABEL: @test_smallpartinit_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
 // ZERO-O1-LEGACY: store i16 0, i16* %uninit, align 2
@@ -680,7 +552,7 @@
 // CHECK:       %uninit = alloca %struct.padded, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_padded_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_padded_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 8, i1 false)
 // PATTERN-O1: store i64 -6148914691236517206, i64* %uninit, align 8
 // ZERO-LABEL: @test_padded_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
@@ -706,7 +578,7 @@
 // CHECK-NEXT:  call void @{{.*}}paddednullinit{{.*}}%uninit)
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_paddednullinit_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_paddednullinit_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 8, i1 false)
 // PATTERN-O1-LEGACY: store i64 -6148914691236517206, i64* %uninit, align 8
 // PATTERN-O1-NEWPM: store i64 2863311360, i64* %uninit, align 8
 // ZERO-LABEL: @test_paddednullinit_uninit()
@@ -736,11 +608,8 @@
 // CHECK:       %uninit = alloca %struct.paddedpacked, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_paddedpacked_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_paddedpacked_uninit.uninit
-// PATTERN-O1:  %[[C:[^ ]*]] = getelementptr inbounds {{.*}}%uninit, i64 0, i32 0
-// PATTERN-O1  store i8 -86, i8* %[[C]], align
-// PATTERN-O1:  %[[I:[^ ]*]] = getelementptr inbounds {{.*}}%uninit, i64 0, i32 1
-// PATTERN-O1: store i32 -1431655766, i32* %[[I]], align
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 5, i1 false)
+// PATTERN-O1: call void @llvm.memset{{.*}}, i8 -86, i64 5, i1 false)
 
 // ZERO-LABEL: @test_paddedpacked_uninit()
 // ZERO: call void @llvm.memset{{.*}}, i8 0,
@@ -764,7 +633,7 @@
 // CHECK:       %uninit = alloca %struct.paddedpackedarray, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_paddedpackedarray_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_paddedpackedarray_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 10, i1 false)
 // PATTERN-O1: getelementptr
 // PATTERN-O1: call void @llvm.memset{{.*}}({{.*}}i8 -86, i64 10
 // ZERO-LABEL: @test_paddedpackedarray_uninit()
@@ -786,14 +655,14 @@
 
 TEST_UNINIT(unpackedinpacked, unpackedinpacked);
 // CHECK-LABEL: @test_unpackedinpacked_uninit()
-// PATTERN-O0:  call void @llvm.memcpy{{.*}}, i64 9, i1 false)
+// PATTERN-O0:  call void @llvm.memset{{.*}}, i8 -86, i64 9, i1 false)
 
 TEST_UNINIT(paddednested, paddednested);
 // CHECK-LABEL: @test_paddednested_uninit()
 // CHECK:       %uninit = alloca %struct.paddednested, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_paddednested_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_paddednested_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 16, i1 false)
 // PATTERN-O1: getelementptr
 // PATTERN-O1: call void @llvm.memset{{.*}}({{.*}}, i8 -86, i64 16
 // ZERO-LABEL: @test_paddednested_uninit()
@@ -818,7 +687,7 @@
 // CHECK:       %uninit = alloca %struct.paddedpackednested, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_paddedpackednested_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_paddedpackednested_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 10, i1 false)
 // PATTERN-O1: getelementptr
 // PATTERN-O1: call void @llvm.memset.p0i8.i64(i8* nonnull align 1 %0, i8 -86, i64 10, i1 false
 // ZERO-LABEL: @test_paddedpackednested_uninit()
@@ -843,7 +712,7 @@
 // CHECK:       %uninit = alloca %struct.bitfield, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_bitfield_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_bitfield_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 4, i1 false)
 // PATTERN-O1: store i32 -1431655766, i32* %uninit, align 4
 // ZERO-LABEL: @test_bitfield_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
@@ -853,14 +722,14 @@
 // CHECK-LABEL: @test_bitfield_braces()
 // CHECK:       %braces = alloca %struct.bitfield, align
 // CHECK-NEXT:  bitcast
-// CHECK-NEXT:  call void @llvm.memcpy
+// CHECK-NEXT:  call void @llvm.memset
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%braces)
 
 TEST_CUSTOM(bitfield, bitfield, { 4, 1 });
 // CHECK-LABEL: @test_bitfield_custom()
 // CHECK:       %custom = alloca %struct.bitfield, align
 // CHECK-NEXT:  bitcast
-// CHECK-NEXT:  call void @llvm.memcpy
+// CHECK-NEXT:  call void @llvm.memset
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%custom)
 
 TEST_UNINIT(bitfieldaligned, bitfieldaligned);
@@ -868,7 +737,7 @@
 // CHECK:       %uninit = alloca %struct.bitfieldaligned, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_bitfieldaligned_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_bitfieldaligned_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 8, i1 false)
 // PATTERN-O1: store i64 -6148914691236517206, i64* %uninit, align 8
 // ZERO-LABEL: @test_bitfieldaligned_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
@@ -878,7 +747,7 @@
 // CHECK-LABEL: @test_bitfieldaligned_braces()
 // CHECK:       %braces = alloca %struct.bitfieldaligned, align
 // CHECK-NEXT:  bitcast
-// CHECK-NEXT:  call void @llvm.memcpy
+// CHECK-NEXT:  call void @llvm.memset
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%braces)
 
 TEST_CUSTOM(bitfieldaligned, bitfieldaligned, { 4, 1  });
@@ -916,7 +785,7 @@
 // CHECK:       %uninit = alloca %struct.arraytail, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_arraytail_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_arraytail_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 4, i1 false)
 // PATTERN-O1: store i32 -1431655766, {{.*}} align 4
 // ZERO-LABEL: @test_arraytail_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
@@ -959,7 +828,7 @@
 // CHECK:       %uninit = alloca [1 x i32], align [[ALIGN:[0-9]*]]
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_int1_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_int1_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 4, i1 false)
 // PATTERN-O1: store i32 -1431655766, {{.*}} align 4
 // ZERO-LABEL: @test_int1_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
@@ -976,7 +845,7 @@
 // CHECK-LABEL: @test_int1_custom()
 // CHECK:       %custom = alloca [1 x i32], align
 // CHECK-NEXT:  bitcast
-// CHECK-NEXT:  call void @llvm.memcpy
+// CHECK-NEXT:  call void @llvm.memset
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%custom)
 
 TEST_UNINIT(int64, int[64]);
@@ -1007,7 +876,7 @@
 // CHECK:       %uninit = alloca [4 x i8], align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_bool4_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_bool4_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 4, i1 false)
 // PATTERN-O1: store i32 -1431655766, i32* %uninit, align 4
 // ZERO-LABEL: @test_bool4_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
@@ -1024,7 +893,7 @@
 // CHECK-LABEL: @test_bool4_custom()
 // CHECK:       %custom = alloca [4 x i8], align
 // CHECK-NEXT:  bitcast
-// CHECK-NEXT:  call void @llvm.memcpy
+// CHECK-NEXT:  call void @llvm.memset
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%custom)
 
 TEST_UNINIT(intptr4, int*[4]);
@@ -1032,8 +901,8 @@
 // CHECK:            %uninit = alloca [4 x i32*], align
 // CHECK-NEXT:       call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-O1-LABEL: @test_intptr4_uninit()
-// PATTERN-O1:       %1 = bitcast [4 x i32*]* %uninit to i8*
-// PATTERN-O1-NEXT:  call void @llvm.memset.p0i8.i64(i8* nonnull align 16 %1, i8 -86, i64 32, i1 false)
+// PATTERN-O1:       [[C:%[0-9]+]] = bitcast [4 x i32*]* %uninit to i8*
+// PATTERN-O1:       call void @llvm.memset.p0i8.i64(i8* nonnull align 16 [[C]], i8 -86, i64 32, i1 false)
 // ZERO-LABEL:       @test_intptr4_uninit()
 // ZERO:             call void @llvm.memset{{.*}}, i8 0,
 
@@ -1056,7 +925,7 @@
 // CHECK:       %uninit = alloca [4 x %struct.tailpad], align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_tailpad4_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_tailpad4_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 16, i1 false)
 // PATTERN-O1: bitcast
 // PATTERN-O1: call void @llvm.memset{{.*}}({{.*}}0, i8 -86, i64 16
 // ZERO-LABEL: @test_tailpad4_uninit()
@@ -1073,7 +942,7 @@
 // CHECK-LABEL: @test_tailpad4_custom()
 // CHECK:       %custom = alloca [4 x %struct.tailpad], align
 // CHECK-NEXT:  bitcast
-// CHECK-NEXT:  call void @llvm.memcpy
+// CHECK-NEXT:  call void @llvm.memset
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%custom)
 
 TEST_UNINIT(tailpad9, tailpad[9]);
@@ -1132,7 +1001,7 @@
 // CHECK:       %uninit = alloca %struct.notlockfree, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_atomicnotlockfree_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_atomicnotlockfree_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 32, i1 false)
 // PATTERN-O1: bitcast
 // PATTERN-O1: call void @llvm.memset{{.*}}({{.*}}, i8 -86, i64 32
 // ZERO-LABEL: @test_atomicnotlockfree_uninit()
@@ -1143,7 +1012,7 @@
 // CHECK:       %uninit = alloca %struct.padded, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_atomicpadded_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_atomicpadded_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 8, i1 false)
 // PATTERN-O1: store i64 -6148914691236517206, i64* %uninit, align 8
 // ZERO-LABEL: @test_atomicpadded_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
@@ -1154,7 +1023,7 @@
 // CHECK:       %uninit = alloca %struct.tailpad, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_atomictailpad_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_atomictailpad_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 4, i1 false)
 // ZERO-LABEL: @test_atomictailpad_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
 // ZERO-O1: store i32 0, i32* %uninit, align 4
@@ -1164,11 +1033,8 @@
 // CHECK:       %uninit = alloca { float, float }, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_complexfloat_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_complexfloat_uninit.uninit
-// PATTERN-O1:  %[[F1:[^ ]*]] = getelementptr inbounds {{.*}}%uninit, i64 0, i32 0
-// PATTERN-O1  store float 0xFFFFFFFFE0000000, float* %[[F1]], align
-// PATTERN-O1:  %[[F2:[^ ]*]] = getelementptr inbounds {{.*}}%uninit, i64 0, i32 1
-// PATTERN-O1: store float 0xFFFFFFFFE0000000, float* %[[F2]], align
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -1, i64 8, i1 false)
+// PATTERN-O1: store i64 -1, i64* %uninit, align 8
 
 // ZERO-LABEL: @test_complexfloat_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
@@ -1197,7 +1063,7 @@
 // CHECK:       %uninit = alloca { double, double }, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_complexdouble_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_complexdouble_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -1, i64 16, i1 false)
 // ZERO-LABEL: @test_complexdouble_uninit()
 // ZERO: call void @llvm.memset{{.*}}, i8 0,
 
@@ -1240,7 +1106,7 @@
 // CHECK:       %uninit = alloca %struct.semivolatile, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_semivolatile_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_semivolatile_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 8, i1 false)
 // ZERO-LABEL: @test_semivolatile_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
 // ZERO-O1: store i64 0, i64* %uninit, align 8
@@ -1256,7 +1122,7 @@
 // CHECK-LABEL: @test_semivolatile_custom()
 // CHECK:       %custom = alloca %struct.semivolatile, align
 // CHECK-O0:  bitcast
-// CHECK-O0:  call void @llvm.memcpy
+// CHECK-O0:  call void @llvm.memset
 // CHECK-O0:  call void @{{.*}}used{{.*}}%custom)
 // CHECK-O1:  store i64 4919131752989213764, i64* %custom, align 8
 
@@ -1291,7 +1157,7 @@
 // CHECK-NEXT:  call void @{{.*}}base{{.*}}%uninit)
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_base_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_base_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 8, i1 false)
 // ZERO-LABEL: @test_base_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
 // ZERO-O1-LEGACY: store i64 0, {{.*}} align 8
@@ -1311,7 +1177,7 @@
 // CHECK-NEXT:  call void @{{.*}}derived{{.*}}%uninit)
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_derived_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_derived_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 8, i1 false)
 // ZERO-LABEL: @test_derived_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
 // ZERO-O1-LEGACY: store i64 0, {{.*}} align 8
@@ -1331,7 +1197,7 @@
 // CHECK-NEXT:  call void @{{.*}}virtualderived{{.*}}%uninit)
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_virtualderived_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_virtualderived_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 16, i1 false)
 // ZERO-LABEL: @test_virtualderived_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
 // ZERO-O1-LEGACY: call void @llvm.memset{{.*}}, i8 0,
@@ -1354,7 +1220,7 @@
 // CHECK:       %uninit = alloca %union.matching, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_matching_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_matching_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 4, i1 false)
 // ZERO-LABEL: @test_matching_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
 // ZERO-O1: store i32 0, {{.*}} align 4
@@ -1380,8 +1246,9 @@
 // CHECK:       %uninit = alloca %union.matchingreverse, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_matchingreverse_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_matchingreverse_uninit.uninit
-// PATTERN-O1: store float 0xFFFFFFFFE0000000
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -1, i64 4, i1 false)
+// PATTERN-O1: [[F:%[0-9]+]] = bitcast %union.matchingreverse* %uninit to i32*
+// PATTERN-O1: store i32 -1, i32* [[F]], align 4
 // ZERO-LABEL: @test_matchingreverse_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
 // ZERO-O1: store i32 0, {{.*}} align 4
@@ -1406,7 +1273,7 @@
 // CHECK:       %uninit = alloca %union.unmatched, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_unmatched_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_unmatched_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 4, i1 false)
 // ZERO-LABEL: @test_unmatched_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
 // ZERO-O1: store i32 0, {{.*}} align 4
@@ -1415,7 +1282,7 @@
 // CHECK-LABEL: @test_unmatched_braces()
 // CHECK:       %braces = alloca %union.unmatched, align
 // CHECK-NEXT:  bitcast
-// CHECK-NEXT:  call void @llvm.memcpy
+// CHECK-NEXT:  call void @llvm.memset
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%braces)
 
 TEST_CUSTOM(unmatched, unmatched, { .i = 0x3badbeef });
@@ -1431,7 +1298,7 @@
 // CHECK:       %uninit = alloca %union.unmatchedreverse, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_unmatchedreverse_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_unmatchedreverse_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -86, i64 4, i1 false)
 // ZERO-LABEL: @test_unmatchedreverse_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
 // ZERO-O1:  store i32 0, {{.*}} align 4
@@ -1447,7 +1314,7 @@
 // CHECK-LABEL: @test_unmatchedreverse_custom()
 // CHECK:       %custom = alloca %union.unmatchedreverse, align
 // CHECK-O0:    bitcast
-// CHECK-O0:    call void @llvm.memcpy
+// CHECK-O0:    call void @llvm.memset
 // CHECK-O0:    call void @{{.*}}used{{.*}}%custom)
 // PATTERN-O1:  store i32 -1431655894, i32* {{.*}}, align 4
 // ZERO-O1:     store i32 42, i32* {{.*}}, align 4
@@ -1457,7 +1324,7 @@
 // CHECK:       %uninit = alloca %union.unmatchedfp, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_unmatchedfp_uninit()
-// PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_unmatchedfp_uninit.uninit
+// PATTERN-O0: call void @llvm.memset{{.*}}, i8 -1, i64 8, i1 false)
 // ZERO-LABEL: @test_unmatchedfp_uninit()
 // ZERO-O0: call void @llvm.memset{{.*}}, i8 0,
 // ZERO-O1: store i64 0, {{.*}} align 8
@@ -1466,7 +1333,7 @@
 // CHECK-LABEL: @test_unmatchedfp_braces()
 // CHECK:       %braces = alloca %union.unmatchedfp, align
 // CHECK-NEXT:  bitcast
-// CHECK-NEXT:  call void @llvm.memcpy
+// CHECK-NEXT:  call void @llvm.memset
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%braces)
 
 TEST_CUSTOM(unmatchedfp, unmatchedfp, { .d = 3.1415926535897932384626433 });
diff --git a/clang/test/CodeGenCXX/references.cpp b/clang/test/CodeGenCXX/references.cpp
--- a/clang/test/CodeGenCXX/references.cpp
+++ b/clang/test/CodeGenCXX/references.cpp
@@ -281,7 +281,7 @@
   struct a { int a : 10, b : 10; };
   // CHECK-LABEL: define void @_ZN6PR95651fEv()
   void f() {
-    // CHECK: call void @llvm.memcpy
+    // CHECK: call void @llvm.memset
     a x = { 0, 0 };
     // CHECK: [[WITH_SEVENTEEN:%[.a-zA-Z0-9]+]] = or i32 [[WITHOUT_SEVENTEEN:%[.a-zA-Z0-9]+]], 17
     // CHECK: store i32 [[WITH_SEVENTEEN]], i32* [[XA:%[.a-zA-Z0-9]+]]