diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -2492,6 +2492,30 @@
     if (!CI->getArgOperand(2)->getType()->isPointerTy())
       return nullptr;
 
+    if (CI->use_empty())
+      // sprintf(dest, "%s", str) -> strcpy(dest, str)
+      return emitStrCpy(CI->getArgOperand(0), CI->getArgOperand(2), B, TLI);
+
+    uint64_t SrcLen = GetStringLength(CI->getArgOperand(2));
+    if (SrcLen) {
+      B.CreateMemCpy(
+          CI->getArgOperand(0), Align(1), CI->getArgOperand(2), Align(1),
+          ConstantInt::get(DL.getIntPtrType(CI->getContext()), SrcLen));
+      // Returns total number of characters written without null-character.
+      return ConstantInt::get(DL.getIntPtrType(CI->getContext()), SrcLen - 1);
+    } else if (Value *V = emitStpCpy(CI->getArgOperand(0), CI->getArgOperand(2),
+                                     B, TLI)) {
+      // sprintf(dest, "%s", str) -> stpcpy(dest, str) - dest
+      Value *PtrDiff = B.CreatePtrDiff(V, CI->getArgOperand(0));
+      return B.CreateIntCast(PtrDiff, CI->getType(), false);
+    }
+
+    bool OptForSize = CI->getFunction()->hasOptSize() ||
+                      llvm::shouldOptimizeForSize(CI->getParent(), PSI, BFI,
+                                                  PGSOQueryType::IRPass);
+    if (OptForSize)
+      return nullptr;
+
     Value *Len = emitStrLen(CI->getArgOperand(2), B, DL, TLI);
     if (!Len)
       return nullptr;
diff --git a/llvm/test/Transforms/InstCombine/2010-05-30-memcpy-Struct.ll b/llvm/test/Transforms/InstCombine/2010-05-30-memcpy-Struct.ll
--- a/llvm/test/Transforms/InstCombine/2010-05-30-memcpy-Struct.ll
+++ b/llvm/test/Transforms/InstCombine/2010-05-30-memcpy-Struct.ll
@@ -1,3 +1,4 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt -instcombine -S < %s | FileCheck %s
 ; PR7265
 
@@ -9,10 +10,14 @@
 @.str = private constant [3 x i8] c"%s\00"
 
 define void @CopyEventArg(%union.anon* %ev) nounwind {
+; CHECK-LABEL: @CopyEventArg(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CSTR:%.*]] = bitcast %union.anon* [[EV:%.*]] to i8*
+; CHECK-NEXT:    [[STRCPY:%.*]] = call i8* @strcpy(i8* nonnull dereferenceable(1) undef, i8* nonnull dereferenceable(1) [[CSTR]])
+; CHECK-NEXT:    ret void
+;
 entry:
   %call = call i32 (i8*, i8*, ...) @sprintf(i8* undef, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), %union.anon* %ev) nounwind
-; CHECK: bitcast %union.anon* %ev to i8*
-; CHECK: call void @llvm.memcpy.p0i8.p0i8.i64
   ret void
 }
 
diff --git a/llvm/test/Transforms/InstCombine/sprintf-1.ll b/llvm/test/Transforms/InstCombine/sprintf-1.ll
--- a/llvm/test/Transforms/InstCombine/sprintf-1.ll
+++ b/llvm/test/Transforms/InstCombine/sprintf-1.ll
@@ -2,7 +2,8 @@
 ; Test that the sprintf library call simplifier works correctly.
 ;
 ; RUN: opt < %s -instcombine -S | FileCheck %s
-; RUN: opt < %s -mtriple xcore-xmos-elf -instcombine -S | FileCheck %s -check-prefix=CHECK-IPRINTF
+; RUN: opt < %s -mtriple xcore-xmos-elf -instcombine -S | FileCheck %s -check-prefixes=CHECK,CHECK-IPRINTF
+; RUN: opt < %s -mtriple=i386-pc-windows-msvc -instcombine -S | FileCheck %s --check-prefixes=CHECK,WIN
 
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
 
@@ -23,10 +24,6 @@
 ; CHECK-LABEL: @test_simplify1(
 ; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i32(i8* nonnull align 1 dereferenceable(13) [[DST:%.*]], i8* nonnull align 1 dereferenceable(13) getelementptr inbounds ([13 x i8], [13 x i8]* @hello_world, i32 0, i32 0), i32 13, i1 false)
 ; CHECK-NEXT:    ret void
-;
-; CHECK-IPRINTF-LABEL: @test_simplify1(
-; CHECK-IPRINTF-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i32(i8* nonnull align 1 dereferenceable(13) [[DST:%.*]], i8* nonnull align 1 dereferenceable(13) getelementptr inbounds ([13 x i8], [13 x i8]* @hello_world, i32 0, i32 0), i32 13, i1 false)
-; CHECK-IPRINTF-NEXT:    ret void
 ;
   %fmt = getelementptr [13 x i8], [13 x i8]* @hello_world, i32 0, i32 0
   call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt)
@@ -37,10 +34,6 @@
 ; CHECK-LABEL: @test_simplify2(
 ; CHECK-NEXT:    store i8 0, i8* [[DST:%.*]], align 1
 ; CHECK-NEXT:    ret void
-;
-; CHECK-IPRINTF-LABEL: @test_simplify2(
-; CHECK-IPRINTF-NEXT:    store i8 0, i8* [[DST:%.*]], align 1
-; CHECK-IPRINTF-NEXT:    ret void
 ;
   %fmt = getelementptr [1 x i8], [1 x i8]* @null, i32 0, i32 0
   call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt)
@@ -51,10 +44,6 @@
 ; CHECK-LABEL: @test_simplify3(
 ; CHECK-NEXT:    store i8 0, i8* [[DST:%.*]], align 1
 ; CHECK-NEXT:    ret void
-;
-; CHECK-IPRINTF-LABEL: @test_simplify3(
-; CHECK-IPRINTF-NEXT:    store i8 0, i8* [[DST:%.*]], align 1
-; CHECK-IPRINTF-NEXT:    ret void
 ;
   %fmt = getelementptr [7 x i8], [7 x i8]* @null_hello, i32 0, i32 0
   call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt)
@@ -69,32 +58,18 @@
 ; CHECK-NEXT:    [[NUL:%.*]] = getelementptr i8, i8* [[DST]], i32 1
 ; CHECK-NEXT:    store i8 0, i8* [[NUL]], align 1
 ; CHECK-NEXT:    ret void
-;
-; CHECK-IPRINTF-LABEL: @test_simplify4(
-; CHECK-IPRINTF-NEXT:    store i8 104, i8* [[DST:%.*]], align 1
-; CHECK-IPRINTF-NEXT:    [[NUL:%.*]] = getelementptr i8, i8* [[DST]], i32 1
-; CHECK-IPRINTF-NEXT:    store i8 0, i8* [[NUL]], align 1
-; CHECK-IPRINTF-NEXT:    ret void
 ;
   %fmt = getelementptr [3 x i8], [3 x i8]* @percent_c, i32 0, i32 0
   call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt, i8 104)
   ret void
 }
 
-; Check sprintf(dst, "%s", str) -> llvm.memcpy(dest, str, strlen(str) + 1, 1).
+; Check sprintf(dst, "%s", str) -> strcpy(dst, "%s", str) if result is unused.
 
 define void @test_simplify5(i8* %dst, i8* %str) {
 ; CHECK-LABEL: @test_simplify5(
-; CHECK-NEXT:    [[STRLEN:%.*]] = call i32 @strlen(i8* nonnull dereferenceable(1) [[STR:%.*]])
-; CHECK-NEXT:    [[LENINC:%.*]] = add i32 [[STRLEN]], 1
-; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 1 [[DST:%.*]], i8* align 1 [[STR]], i32 [[LENINC]], i1 false)
+; CHECK-NEXT:    [[STRCPY:%.*]] = call i8* @strcpy(i8* nonnull dereferenceable(1) [[DST:%.*]], i8* nonnull dereferenceable(1) [[STR:%.*]])
 ; CHECK-NEXT:    ret void
-;
-; CHECK-IPRINTF-LABEL: @test_simplify5(
-; CHECK-IPRINTF-NEXT:    [[STRLEN:%.*]] = call i32 @strlen(i8* nonnull dereferenceable(1) [[STR:%.*]])
-; CHECK-IPRINTF-NEXT:    [[LENINC:%.*]] = add i32 [[STRLEN]], 1
-; CHECK-IPRINTF-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 1 [[DST:%.*]], i8* align 1 [[STR]], i32 [[LENINC]], i1 false)
-; CHECK-IPRINTF-NEXT:    ret void
 ;
   %fmt = getelementptr [3 x i8], [3 x i8]* @percent_s, i32 0, i32 0
   call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt, i8* %str)
@@ -104,27 +79,77 @@
 ; Check sprintf(dst, format, ...) -> siprintf(str, format, ...) if no floating.
 
 define void @test_simplify6(i8* %dst) {
-; CHECK-LABEL: @test_simplify6(
-; CHECK-NEXT:    [[TMP1:%.*]] = call i32 (i8*, i8*, ...) @sprintf(i8* nonnull dereferenceable(1) [[DST:%.*]], i8* nonnull dereferenceable(1) getelementptr inbounds ([3 x i8], [3 x i8]* @percent_d, i32 0, i32 0), i32 187)
-; CHECK-NEXT:    ret void
-;
 ; CHECK-IPRINTF-LABEL: @test_simplify6(
 ; CHECK-IPRINTF-NEXT:    [[TMP1:%.*]] = call i32 (i8*, i8*, ...) @siprintf(i8* [[DST:%.*]], i8* getelementptr inbounds ([3 x i8], [3 x i8]* @percent_d, i32 0, i32 0), i32 187)
 ; CHECK-IPRINTF-NEXT:    ret void
+;
+; WIN-LABEL: @test_simplify6(
+; WIN-NEXT:    [[TMP1:%.*]] = call i32 (i8*, i8*, ...) @sprintf(i8* nonnull dereferenceable(1) [[DST:%.*]], i8* nonnull dereferenceable(1) getelementptr inbounds ([3 x i8], [3 x i8]* @percent_d, i32 0, i32 0), i32 187)
+; WIN-NEXT:    ret void
 ;
   %fmt = getelementptr [3 x i8], [3 x i8]* @percent_d, i32 0, i32 0
   call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt, i32 187)
   ret void
 }
 
+; Check sprintf(dst, "%s", str) -> llvm.memcpy(dest, str, strlen(str) + 1, 1).
+
+define i32 @test_simplify7(i8* %dst, i8* %str) {
+; CHECK-IPRINTF-LABEL: @test_simplify7(
+; CHECK-IPRINTF-NEXT:    [[STPCPY:%.*]] = call i8* @stpcpy(i8* [[DST:%.*]], i8* [[STR:%.*]])
+; CHECK-IPRINTF-NEXT:    [[TMP1:%.*]] = ptrtoint i8* [[STPCPY]] to i32
+; CHECK-IPRINTF-NEXT:    [[TMP2:%.*]] = ptrtoint i8* [[DST]] to i32
+; CHECK-IPRINTF-NEXT:    [[TMP3:%.*]] = sub i32 [[TMP1]], [[TMP2]]
+; CHECK-IPRINTF-NEXT:    ret i32 [[TMP3]]
+;
+; WIN-LABEL: @test_simplify7(
+; WIN-NEXT:    [[STRLEN:%.*]] = call i32 @strlen(i8* nonnull dereferenceable(1) [[STR:%.*]])
+; WIN-NEXT:    [[LENINC:%.*]] = add i32 [[STRLEN]], 1
+; WIN-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 1 [[DST:%.*]], i8* align 1 [[STR]], i32 [[LENINC]], i1 false)
+; WIN-NEXT:    ret i32 [[STRLEN]]
+;
+  %fmt = getelementptr [3 x i8], [3 x i8]* @percent_s, i32 0, i32 0
+  %r = call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt, i8* %str)
+  ret i32 %r
+}
+
+; Check sprintf(dst, "%s", str) -> llvm.memcpy(dest, str, strlen(str) + 1, 1).
+define i32 @test_simplify8(i8* %dst) {
+; CHECK-LABEL: @test_simplify8(
+; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i32(i8* nonnull align 1 dereferenceable(13) [[DST:%.*]], i8* nonnull align 1 dereferenceable(13) getelementptr inbounds ([13 x i8], [13 x i8]* @hello_world, i32 0, i32 0), i32 13, i1 false)
+; CHECK-NEXT:    ret i32 12
+;
+  %fmt = getelementptr [3 x i8], [3 x i8]* @percent_s, i32 0, i32 0
+  %str = getelementptr [13 x i8], [13 x i8]* @hello_world, i32 0, i32 0
+  %r = call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt, i8* %str)
+  ret i32 %r
+}
+
+; Check sprintf(dst, "%s", str) -> stpcpy(dest, str) - dest
+
+define i32 @test_simplify9(i8* %dst, i8* %str) {
+; CHECK-IPRINTF-LABEL: @test_simplify9(
+; CHECK-IPRINTF-NEXT:    [[STPCPY:%.*]] = call i8* @stpcpy(i8* [[DST:%.*]], i8* [[STR:%.*]])
+; CHECK-IPRINTF-NEXT:    [[TMP1:%.*]] = ptrtoint i8* [[STPCPY]] to i32
+; CHECK-IPRINTF-NEXT:    [[TMP2:%.*]] = ptrtoint i8* [[DST]] to i32
+; CHECK-IPRINTF-NEXT:    [[TMP3:%.*]] = sub i32 [[TMP1]], [[TMP2]]
+; CHECK-IPRINTF-NEXT:    ret i32 [[TMP3]]
+;
+; WIN-LABEL: @test_simplify9(
+; WIN-NEXT:    [[STRLEN:%.*]] = call i32 @strlen(i8* nonnull dereferenceable(1) [[STR:%.*]])
+; WIN-NEXT:    [[LENINC:%.*]] = add i32 [[STRLEN]], 1
+; WIN-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 1 [[DST:%.*]], i8* align 1 [[STR]], i32 [[LENINC]], i1 false)
+; WIN-NEXT:    ret i32 [[STRLEN]]
+;
+  %fmt = getelementptr [3 x i8], [3 x i8]* @percent_s, i32 0, i32 0
+  %r = call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt, i8* %str)
+  ret i32 %r
+}
+
 define void @test_no_simplify1(i8* %dst) {
 ; CHECK-LABEL: @test_no_simplify1(
 ; CHECK-NEXT:    [[TMP1:%.*]] = call i32 (i8*, i8*, ...) @sprintf(i8* nonnull dereferenceable(1) [[DST:%.*]], i8* nonnull dereferenceable(1) getelementptr inbounds ([3 x i8], [3 x i8]* @percent_f, i32 0, i32 0), double 1.870000e+00)
 ; CHECK-NEXT:    ret void
-;
-; CHECK-IPRINTF-LABEL: @test_no_simplify1(
-; CHECK-IPRINTF-NEXT:    [[TMP1:%.*]] = call i32 (i8*, i8*, ...) @sprintf(i8* nonnull dereferenceable(1) [[DST:%.*]], i8* nonnull dereferenceable(1) getelementptr inbounds ([3 x i8], [3 x i8]* @percent_f, i32 0, i32 0), double 1.870000e+00)
-; CHECK-IPRINTF-NEXT:    ret void
 ;
   %fmt = getelementptr [3 x i8], [3 x i8]* @percent_f, i32 0, i32 0
   call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt, double 1.87)
@@ -135,11 +160,24 @@
 ; CHECK-LABEL: @test_no_simplify2(
 ; CHECK-NEXT:    [[TMP1:%.*]] = call i32 (i8*, i8*, ...) @sprintf(i8* nonnull dereferenceable(1) [[DST:%.*]], i8* nonnull dereferenceable(1) [[FMT:%.*]], double [[D:%.*]])
 ; CHECK-NEXT:    ret void
-;
-; CHECK-IPRINTF-LABEL: @test_no_simplify2(
-; CHECK-IPRINTF-NEXT:    [[TMP1:%.*]] = call i32 (i8*, i8*, ...) @sprintf(i8* nonnull dereferenceable(1) [[DST:%.*]], i8* nonnull dereferenceable(1) [[FMT:%.*]], double [[D:%.*]])
-; CHECK-IPRINTF-NEXT:    ret void
 ;
   call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt, double %d)
   ret void
 }
+
+define i32 @test_no_simplify3(i8* %dst, i8* %str) minsize {
+; CHECK-IPRINTF-LABEL: @test_no_simplify3(
+; CHECK-IPRINTF-NEXT:    [[STPCPY:%.*]] = call i8* @stpcpy(i8* [[DST:%.*]], i8* [[STR:%.*]])
+; CHECK-IPRINTF-NEXT:    [[TMP1:%.*]] = ptrtoint i8* [[STPCPY]] to i32
+; CHECK-IPRINTF-NEXT:    [[TMP2:%.*]] = ptrtoint i8* [[DST]] to i32
+; CHECK-IPRINTF-NEXT:    [[TMP3:%.*]] = sub i32 [[TMP1]], [[TMP2]]
+; CHECK-IPRINTF-NEXT:    ret i32 [[TMP3]]
+;
+; WIN-LABEL: @test_no_simplify3(
+; WIN-NEXT:    [[R:%.*]] = call i32 (i8*, i8*, ...) @sprintf(i8* nonnull dereferenceable(1) [[DST:%.*]], i8* nonnull dereferenceable(1) getelementptr inbounds ([3 x i8], [3 x i8]* @percent_s, i32 0, i32 0), i8* [[STR:%.*]])
+; WIN-NEXT:    ret i32 [[R]]
+;
+  %fmt = getelementptr [3 x i8], [3 x i8]* @percent_s, i32 0, i32 0
+  %r = call i32 (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt, i8* %str)
+  ret i32 %r
+}