Index: include/clang/Basic/Sanitizers.def
===================================================================
--- include/clang/Basic/Sanitizers.def
+++ include/clang/Basic/Sanitizers.def
@@ -159,6 +159,9 @@
 SANITIZER_GROUP("efficiency-all", Efficiency,
                 EfficiencyCacheFrag | EfficiencyWorkingSet)
 
+// Initialize local variables.
+SANITIZER("init-locals", InitLocals)
+
 // Scudo hardened allocator
 SANITIZER("scudo", Scudo)
 
Index: lib/CodeGen/CGDecl.cpp
===================================================================
--- lib/CodeGen/CGDecl.cpp
+++ lib/CodeGen/CGDecl.cpp
@@ -1434,7 +1434,8 @@
     return;
   }
 
-  if (isTrivialInitializer(Init))
+  bool trivial = isTrivialInitializer(Init);
+  if (trivial && !getLangOpts().Sanitize.has(SanitizerKind::InitLocals))
     return;
 
   // Check whether this is a byref variable that's potentially
@@ -1445,8 +1446,15 @@
   Address Loc =
     capturedByInit ? emission.Addr : emission.getObjectAddress(*this);
 
+  bool constantAggregate = emission.IsConstantAggregate;
+
   llvm::Constant *constant = nullptr;
-  if (emission.IsConstantAggregate || D.isConstexpr()) {
+  if (trivial) {
+    QualType Ty = D.getType();
+    constant = CGM.EmitNullConstant(Ty);
+    if (Ty->isArrayType() || Ty->isRecordType())
+      constantAggregate = true;
+  } else if (emission.IsConstantAggregate || D.isConstexpr()) {
     assert(!capturedByInit && "constant init contains a capturing block?");
     constant = ConstantEmitter(*this).tryEmitAbstractForInitializer(D);
   }
@@ -1457,7 +1465,7 @@
     return EmitExprAsInit(Init, &D, lv, capturedByInit);
   }
 
-  if (!emission.IsConstantAggregate) {
+  if (!constantAggregate) {
     // For simple scalar/complex initialization, store the value directly.
     LValue lv = MakeAddrLValue(Loc, type);
     lv.setNonGC(true);
Index: lib/Driver/ToolChain.cpp
===================================================================
--- lib/Driver/ToolChain.cpp
+++ lib/Driver/ToolChain.cpp
@@ -819,7 +819,7 @@
 
   SanitizerMask Res = (Undefined & ~Vptr & ~Function) | (CFI & ~CFIICall) |
                       CFICastStrict | UnsignedIntegerOverflow |
-                      ImplicitConversion | Nullability | LocalBounds;
+                      ImplicitConversion | Nullability | LocalBounds | InitLocals;
   if (getTriple().getArch() == llvm::Triple::x86 ||
       getTriple().getArch() == llvm::Triple::x86_64 ||
       getTriple().getArch() == llvm::Triple::arm ||
Index: test/CodeGen/sanitize-init-locals.c
===================================================================
--- test/CodeGen/sanitize-init-locals.c
+++ test/CodeGen/sanitize-init-locals.c
@@ -0,0 +1,42 @@
+// Test for -fsanitize=init-locals.
+
+// RUN: %clang_cc1 %s -O0 -triple x86_64-unknown-linux-gnu -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 %s -O0 -triple x86_64-unknown-linux-gnu -fsanitize=init-locals -emit-llvm -o - | FileCheck -check-prefixes=CHECK,CHECK-INIT-LOCALS %s
+// RUN: %clang_cc1 %s -O0 -triple x86_64-unknown-linux-gnu -Wuninitialized -emit-llvm -o - 2>&1 | FileCheck -check-prefix=CHECK-WUNINITIALIZED %s
+// RUN: %clang_cc1 %s -O0 -triple x86_64-unknown-linux-gnu -Wuninitialized -fsanitize=init-locals -emit-llvm -o - 2>&1 | FileCheck -check-prefix=CHECK-WUNINITIALIZED %s
+
+
+// CHECK: @testSanitizeInitLocals.local_array_init_part = private unnamed_addr constant [5 x i32] [i32 0, i32 1, i32 2, i32 0, i32 0], align 16
+// CHECK: @testSanitizeInitLocals.local_array_init = private unnamed_addr constant [5 x i32] [i32 0, i32 1, i32 2, i32 3, i32 4], align 16
+
+// CHECK: %local_int_uninit = alloca i32, align 4
+// CHECK: %local_int_init_0 = alloca i32, align 4
+// CHECK: %local_int_init = alloca i32, align 4
+// CHECK: %local_array_uninit = alloca [5 x i32], align 16
+// CHECK: %local_array_init_part = alloca [5 x i32], align 16
+// CHECK: %local_array_init = alloca [5 x i32], align 16
+
+// CHECK-INIT-LOCALS: store i32 0, i32* %local_int_uninit, align 4
+// CHECK: store i32 0, i32* %local_int_init_0, align 4
+// CHECK: store i32 1, i32* %local_int_init, align 4
+//
+// CHECK-INIT-LOCALS: [[CAST0:%.*]] = {{.*}}%local_array_uninit
+// CHECK-INIT-LOCALS: call void @llvm.memset{{.*}}({{.*}}[[CAST0]], i8 0, i64 20
+// CHECK: [[CAST1:%.*]] = {{.*}}%local_array_init_part
+// CHECK: call void @llvm.memcpy{{.*}}({{.*}}[[CAST1]], {{.*}}@testSanitizeInitLocals.local_array_init_part{{.*}}, {{.*}} 20
+// CHECK: [[CAST2:%.*]] = {{.*}}%local_array_init
+// CHECK: call void @llvm.memcpy{{.*}}({{.*}}[[CAST2]], {{.*}}@testSanitizeInitLocals.local_array_init{{.*}}, {{.*}} 20
+
+// CHECK-WUNINITIALIZED: warning: variable 'local_int_uninit' is uninitialized when used here
+
+int testSanitizeInitLocals(void)
+{
+  const int local_int_uninit;
+  const int local_int_init_0 = 0;
+  const int local_int_init = 1;
+  const int local_array_uninit[5];
+  const int local_array_init_part[5] = {0, 1, 2};
+  const int local_array_init[5] = {0, 1, 2, 3, 4};
+  return local_int_uninit;
+}
+