diff --git a/toolsrc/include/vcpkg/base/optional.h b/toolsrc/include/vcpkg/base/optional.h
index fc3733ead4..50586ecc8d 100644
--- a/toolsrc/include/vcpkg/base/optional.h
+++ b/toolsrc/include/vcpkg/base/optional.h
@@ -283,6 +283,21 @@ namespace vcpkg
             }
         }
 
+        friend bool operator==(const Optional& lhs, const Optional& rhs)
+        {
+            if (lhs.m_base.has_value())
+            {
+                if (rhs.m_base.has_value())
+                {
+                    return lhs.m_base.value() == rhs.m_base.value();
+                }
+
+                return false;
+            }
+
+            return !rhs.m_base.has_value();
+        }
+
     private:
         details::OptionalStorage<T> m_base;
     };
@@ -317,4 +332,27 @@ namespace vcpkg
         if (auto p = o.get()) return t != *p;
         return true;
     }
+
+    template<class Container, class Projection>
+    auto common_projection(const Container& input, Projection proj)
+        -> Optional<std::decay_t<decltype(proj(*(input.begin())))>>
+    {
+        const auto last = input.end();
+        auto first = input.begin();
+        if (first == last)
+        {
+            return nullopt;
+        }
+
+        const auto& prototype = proj(*first);
+        while (++first != last)
+        {
+            if (prototype != proj(*first))
+            {
+                return nullopt;
+            }
+        }
+
+        return prototype;
+    }
 }
diff --git a/toolsrc/include/vcpkg/base/system.h b/toolsrc/include/vcpkg/base/system.h
index 907a692a27..4172f0c500 100644
--- a/toolsrc/include/vcpkg/base/system.h
+++ b/toolsrc/include/vcpkg/base/system.h
@@ -21,6 +21,8 @@ namespace vcpkg::System
 
     Optional<CPUArchitecture> to_cpu_architecture(StringView arch);
 
+    ZStringView to_zstring_view(CPUArchitecture arch) noexcept;
+
     CPUArchitecture get_host_processor();
 
     std::vector<CPUArchitecture> get_supported_host_architectures();
@@ -30,4 +32,6 @@ namespace vcpkg::System
     const Optional<fs::path>& get_program_files_platform_bitness();
 
     int get_num_logical_cores();
+
+    Optional<CPUArchitecture> guess_visual_studio_prompt_target_architecture();
 }
diff --git a/toolsrc/include/vcpkg/triplet.h b/toolsrc/include/vcpkg/triplet.h
index 8d8c3e8798..d836dd2302 100644
--- a/toolsrc/include/vcpkg/triplet.h
+++ b/toolsrc/include/vcpkg/triplet.h
@@ -1,6 +1,8 @@
 #pragma once
 
 #include <string>
+#include <vcpkg/base/system.h>
+#include <vcpkg/base/optional.h>
 
 namespace vcpkg
 {
@@ -15,17 +17,18 @@ namespace vcpkg
 
         static const Triplet X86_WINDOWS;
         static const Triplet X64_WINDOWS;
+        static const Triplet ARM_WINDOWS;
+        static const Triplet ARM64_WINDOWS;
         static const Triplet X86_UWP;
         static const Triplet X64_UWP;
         static const Triplet ARM_UWP;
         static const Triplet ARM64_UWP;
-        static const Triplet ARM_WINDOWS;
-        static const Triplet ARM64_WINDOWS;
 
         const std::string& canonical_name() const;
         const std::string& to_string() const;
         void to_string(std::string& out) const;
         size_t hash_code() const;
+        Optional<System::CPUArchitecture> guess_architecture() const noexcept;
 
         bool operator==(Triplet other) const { return this->m_instance == other.m_instance; }
         bool operator<(Triplet other) const { return canonical_name() < other.canonical_name(); }
diff --git a/toolsrc/src/vcpkg-test/optional.cpp b/toolsrc/src/vcpkg-test/optional.cpp
new file mode 100644
index 0000000000..ce728208f4
--- /dev/null
+++ b/toolsrc/src/vcpkg-test/optional.cpp
@@ -0,0 +1,39 @@
+#include <catch2/catch.hpp>
+#include <vcpkg/base/optional.h>
+#include <vector>
+
+namespace
+{
+    struct identity_projection
+    {
+        template<class T>
+        const T& operator()(const T& val) noexcept
+        {
+            return val;
+        }
+    };
+}
+
+TEST_CASE ("equal", "[optional]")
+{
+    using vcpkg::Optional;
+
+    CHECK(Optional<int>{} == Optional<int>{});
+    CHECK(!(Optional<int>{} == Optional<int>{42}));
+    CHECK(!(Optional<int>{42} == Optional<int>{}));
+    CHECK(!(Optional<int>{1729} == Optional<int>{42}));
+    CHECK(Optional<int>{42} == Optional<int>{42});
+}
+
+TEST_CASE ("common_projection", "[optional]")
+{
+    using vcpkg::common_projection;
+    std::vector<int> input;
+    CHECK(!common_projection(input, identity_projection{}).has_value());
+    input.push_back(42);
+    CHECK(common_projection(input, identity_projection{}).value_or_exit(VCPKG_LINE_INFO) == 42);
+    input.push_back(42);
+    CHECK(common_projection(input, identity_projection{}).value_or_exit(VCPKG_LINE_INFO) == 42);
+    input.push_back(1729);
+    CHECK(!common_projection(input, identity_projection{}).has_value());
+}
diff --git a/toolsrc/src/vcpkg-test/system.cpp b/toolsrc/src/vcpkg-test/system.cpp
new file mode 100644
index 0000000000..41e27fe6d9
--- /dev/null
+++ b/toolsrc/src/vcpkg-test/system.cpp
@@ -0,0 +1,159 @@
+#include <catch2/catch.hpp>
+
+#include <Windows.h>
+#include <string>
+#include <vcpkg/base/optional.h>
+#include <vcpkg/base/stringview.h>
+#include <vcpkg/base/zstringview.h>
+#include <vcpkg/base/strings.h>
+#include <vcpkg/base/system.h>
+
+using vcpkg::Optional;
+using vcpkg::StringView;
+using vcpkg::ZStringView;
+using vcpkg::Checks::check_exit;
+using vcpkg::System::get_environment_variable;
+using vcpkg::System::to_cpu_architecture;
+using vcpkg::System::guess_visual_studio_prompt_target_architecture;
+using vcpkg::nullopt;
+using vcpkg::System::CPUArchitecture;
+
+namespace
+{
+    void set_environment_variable(StringView varname, Optional<std::string> value)
+    {
+#if defined(_WIN32)
+        const auto w_varname = vcpkg::Strings::to_utf16(varname);
+        const auto w_varcstr = w_varname.c_str();
+        BOOL exit_code;
+        if (value)
+        {
+            const auto w_value = vcpkg::Strings::to_utf16(value.value_or_exit(VCPKG_LINE_INFO));
+            exit_code = SetEnvironmentVariableW(w_varcstr, w_value.c_str());
+        }
+        else
+        {
+            exit_code = SetEnvironmentVariableW(w_varcstr, nullptr);
+        }
+
+        check_exit(VCPKG_LINE_INFO, exit_code != 0);
+#else  // ^^^ defined(_WIN32) / !defined(_WIN32) vvv
+        std::string tmp;
+        tmp.reserve(varname.size() + value.size() + 1);
+        tmp.append(varname.data(), varname.size());
+        tmp.push_back('=');
+        if (value)
+        {
+            const auto& unpacked = value.value_or_exit(VCPKG_LINE_INFO);
+            tmp.append(unpacked);
+        }
+
+        const int exit_code = putenv(tmp.c_str());
+        check_exit(VCPKG_LINE_INFO, exit_code == 0);
+#endif // defined(_WIN32)
+    }
+
+    struct environment_variable_resetter
+    {
+        explicit environment_variable_resetter(ZStringView varname_)
+            : varname(varname_), old_value(get_environment_variable(varname))
+        {
+        }
+
+        ~environment_variable_resetter() { set_environment_variable(varname, old_value); }
+
+        environment_variable_resetter(const environment_variable_resetter&) = delete;
+        environment_variable_resetter& operator=(const environment_variable_resetter&) = delete;
+
+    private:
+        ZStringView varname;
+        Optional<std::string> old_value;
+    };
+}
+
+TEST_CASE ("[to_cpu_architecture]", "system")
+{
+    struct test_case
+    {
+        Optional<CPUArchitecture> expected;
+        StringView input;
+    };
+
+    const test_case test_cases[] = {
+        {CPUArchitecture::X86, "x86"},
+        {CPUArchitecture::X86, "X86"},
+        {CPUArchitecture::X64, "x64"},
+        {CPUArchitecture::X64, "X64"},
+        {CPUArchitecture::X64, "AmD64"},
+        {CPUArchitecture::ARM, "ARM"},
+        {CPUArchitecture::ARM64, "ARM64"},
+        {nullopt, "ARM6"},
+        {nullopt, "AR"},
+        {nullopt, "Intel"},
+    };
+
+    for (auto&& instance : test_cases)
+    {
+        CHECK(to_cpu_architecture(instance.input) == instance.expected);
+    }
+}
+
+TEST_CASE ("from_cpu_architecture", "[system]")
+{
+    struct test_case
+    {
+        CPUArchitecture input;
+        ZStringView expected;
+    };
+
+    const test_case test_cases[] = {
+        {CPUArchitecture::X86, "x86"},
+        {CPUArchitecture::X64, "x64"},
+        {CPUArchitecture::ARM, "arm"},
+        {CPUArchitecture::ARM64, "arm64"},
+    };
+
+    for (auto&& instance : test_cases)
+    {
+        CHECK(to_zstring_view(instance.input) == instance.expected);
+    }
+}
+
+TEST_CASE ("guess_visual_studio_prompt", "[system]")
+{
+    environment_variable_resetter reset_VSCMD_ARG_TGT_ARCH{"VSCMD_ARG_TGT_ARCH"};
+    environment_variable_resetter reset_VCINSTALLDIR{"VCINSTALLDIR"};
+    environment_variable_resetter reset_Platform{"Platform"};
+
+    set_environment_variable("Platform", "x86"); // ignored if VCINSTALLDIR unset
+    set_environment_variable("VCINSTALLDIR", nullopt);
+    set_environment_variable("VSCMD_ARG_TGT_ARCH", nullopt);
+    CHECK(!guess_visual_studio_prompt_target_architecture().has_value());
+    set_environment_variable("VSCMD_ARG_TGT_ARCH", "x86");
+    CHECK(guess_visual_studio_prompt_target_architecture()
+        .value_or_exit(VCPKG_LINE_INFO) == CPUArchitecture::X86);
+    set_environment_variable("VSCMD_ARG_TGT_ARCH", "x64");
+    CHECK(guess_visual_studio_prompt_target_architecture()
+        .value_or_exit(VCPKG_LINE_INFO) == CPUArchitecture::X64);
+    set_environment_variable("VSCMD_ARG_TGT_ARCH", "arm");
+    CHECK(guess_visual_studio_prompt_target_architecture()
+        .value_or_exit(VCPKG_LINE_INFO) == CPUArchitecture::ARM);
+    set_environment_variable("VSCMD_ARG_TGT_ARCH", "arm64");
+    CHECK(guess_visual_studio_prompt_target_architecture()
+        .value_or_exit(VCPKG_LINE_INFO) == CPUArchitecture::ARM64);
+
+    // check that apparent "nested" prompts defer to "vsdevcmd"
+    set_environment_variable("VCINSTALLDIR", "anything");
+    CHECK(guess_visual_studio_prompt_target_architecture()
+        .value_or_exit(VCPKG_LINE_INFO) == CPUArchitecture::ARM64);
+    set_environment_variable("VSCMD_ARG_TGT_ARCH", nullopt);
+    set_environment_variable("Platform", nullopt);
+    CHECK(guess_visual_studio_prompt_target_architecture()
+        .value_or_exit(VCPKG_LINE_INFO) == CPUArchitecture::X86);
+    set_environment_variable("Platform", "x86");
+    CHECK(guess_visual_studio_prompt_target_architecture()
+        .value_or_exit(VCPKG_LINE_INFO) == CPUArchitecture::X86);
+    set_environment_variable("Platform", "x64");
+    CHECK(guess_visual_studio_prompt_target_architecture()
+        .value_or_exit(VCPKG_LINE_INFO) == CPUArchitecture::X64);
+}
diff --git a/toolsrc/src/vcpkg/base/checks.cpp b/toolsrc/src/vcpkg/base/checks.cpp
index 6093b5188e..42e0835c6b 100644
--- a/toolsrc/src/vcpkg/base/checks.cpp
+++ b/toolsrc/src/vcpkg/base/checks.cpp
@@ -15,7 +15,7 @@ namespace vcpkg
         g_shutdown_handler = func;
     }
 
-    void Checks::final_cleanup_and_exit(const int exit_code)
+    [[noreturn]] void Checks::final_cleanup_and_exit(const int exit_code)
     {
         static std::atomic<bool> have_entered{false};
         if (have_entered.exchange(true))
@@ -37,7 +37,7 @@ namespace vcpkg
         std::exit(exit_code);
     }
 
-    void Checks::unreachable(const LineInfo& line_info)
+    [[noreturn]] void Checks::unreachable(const LineInfo& line_info)
     {
         System::print2(System::Color::error, "Error: Unreachable code was reached\n");
         System::print2(System::Color::error, line_info, '\n'); // Always print line_info here
@@ -48,13 +48,13 @@ namespace vcpkg
 #endif
     }
 
-    void Checks::exit_with_code(const LineInfo& line_info, const int exit_code)
+    [[noreturn]] void Checks::exit_with_code(const LineInfo& line_info, const int exit_code)
     {
         Debug::print(System::Color::error, line_info, '\n');
         final_cleanup_and_exit(exit_code);
     }
 
-    void Checks::exit_with_message(const LineInfo& line_info, StringView error_message)
+    [[noreturn]] void Checks::exit_with_message(const LineInfo& line_info, StringView error_message)
     {
         System::print2(System::Color::error, error_message, '\n');
         exit_fail(line_info);
diff --git a/toolsrc/src/vcpkg/base/system.cpp b/toolsrc/src/vcpkg/base/system.cpp
index 96cdeb84af..f49632cac0 100644
--- a/toolsrc/src/vcpkg/base/system.cpp
+++ b/toolsrc/src/vcpkg/base/system.cpp
@@ -22,6 +22,18 @@ namespace vcpkg
         return nullopt;
     }
 
+    ZStringView System::to_zstring_view(CPUArchitecture arch) noexcept
+    {
+        switch (arch)
+        {
+            case CPUArchitecture::X86: return "x86";
+            case CPUArchitecture::X64: return "x64";
+            case CPUArchitecture::ARM: return "arm";
+            case CPUArchitecture::ARM64: return "arm64";
+            default: Checks::exit_with_message(VCPKG_LINE_INFO, "unexpected vcpkg::System::CPUArchitecture");
+        }
+    }
+
     CPUArchitecture System::get_host_processor()
     {
 #if defined(_WIN32)
@@ -30,7 +42,7 @@ namespace vcpkg
 
         const auto procarch = get_environment_variable("PROCESSOR_ARCHITECTURE").value_or_exit(VCPKG_LINE_INFO);
         return to_cpu_architecture(procarch).value_or_exit(VCPKG_LINE_INFO);
-#else
+#else // ^^^ defined(_WIN32) / !defined(_WIN32) vvv
 #if defined(__x86_64__) || defined(_M_X64)
         return CPUArchitecture::X64;
 #elif defined(__x86__) || defined(_M_X86)
@@ -39,10 +51,10 @@ namespace vcpkg
         return CPUArchitecture::ARM;
 #elif defined(__aarch64__) || defined(_M_ARM64)
         return CPUArchitecture::ARM64;
-#else
+#else // choose architecture
 #error "Unknown host architecture"
-#endif
-#endif
+#endif // choose architecture
+#endif // defined(_WIN32)
     }
 
     std::vector<CPUArchitecture> System::get_supported_host_architectures()
@@ -67,7 +79,7 @@ namespace vcpkg
         {
             supported_architectures.push_back(CPUArchitecture::X86);
         }
-#endif
+#endif // defined(_WIN32)
 
         return supported_architectures;
     }
@@ -86,11 +98,11 @@ namespace vcpkg
         Checks::check_exit(VCPKG_LINE_INFO, sz2 + 1 == sz);
         ret.pop_back();
         return Strings::to_utf8(ret.c_str());
-#else
+#else  // ^^^ defined(_WIN32) / !defined(_WIN32) vvv
         auto v = getenv(varname.c_str());
         if (!v) return nullopt;
         return std::string(v);
-#endif
+#endif // defined(_WIN32)
     }
 
 #if defined(_WIN32)
@@ -125,13 +137,13 @@ namespace vcpkg
         ret.pop_back(); // remove extra trailing null byte
         return Strings::to_utf8(ret);
     }
-#else
+#else // ^^^ defined(_WIN32) / !defined(_WIN32) vvv
     Optional<std::string> System::get_registry_string(void*, StringView, StringView) { return nullopt; }
-#endif
+#endif // defined(_WIN32)
 
     static const Optional<fs::path>& get_program_files()
     {
-        static const auto PATH = []() -> Optional<fs::path> {
+        static const auto PROGRAMFILES = []() -> Optional<fs::path> {
             auto value = System::get_environment_variable("PROGRAMFILES");
             if (auto v = value.get())
             {
@@ -141,12 +153,12 @@ namespace vcpkg
             return nullopt;
         }();
 
-        return PATH;
+        return PROGRAMFILES;
     }
 
     const Optional<fs::path>& System::get_program_files_32_bit()
     {
-        static const auto PATH = []() -> Optional<fs::path> {
+        static const auto PROGRAMFILES_x86 = []() -> Optional<fs::path> {
             auto value = System::get_environment_variable("ProgramFiles(x86)");
             if (auto v = value.get())
             {
@@ -154,12 +166,12 @@ namespace vcpkg
             }
             return get_program_files();
         }();
-        return PATH;
+        return PROGRAMFILES_x86;
     }
 
     const Optional<fs::path>& System::get_program_files_platform_bitness()
     {
-        static const auto PATH = []() -> Optional<fs::path> {
+        static const auto ProgramW6432 = []() -> Optional<fs::path> {
             auto value = System::get_environment_variable("ProgramW6432");
             if (auto v = value.get())
             {
@@ -167,10 +179,36 @@ namespace vcpkg
             }
             return get_program_files();
         }();
-        return PATH;
+        return ProgramW6432;
     }
 
     int System::get_num_logical_cores() { return std::thread::hardware_concurrency(); }
+
+    Optional<CPUArchitecture> System::guess_visual_studio_prompt_target_architecture()
+    {
+        // Check for the "vsdevcmd" infrastructure used by Visual Studio 2017 and later
+        const auto VSCMD_ARG_TGT_ARCH = System::get_environment_variable("VSCMD_ARG_TGT_ARCH");
+        if (VSCMD_ARG_TGT_ARCH)
+        {
+            return to_cpu_architecture(VSCMD_ARG_TGT_ARCH.value_or_exit(VCPKG_LINE_INFO));
+        }
+
+        // Check for the "vcvarsall" infrastructure used by Visual Studio 2015
+        if (System::get_environment_variable("VCINSTALLDIR"))
+        {
+            const auto Platform = System::get_environment_variable("Platform");
+            if (Platform)
+            {
+                return to_cpu_architecture(Platform.value_or_exit(VCPKG_LINE_INFO));
+            }
+            else
+            {
+                return CPUArchitecture::X86;
+            }
+        }
+
+        return nullopt;
+    }
 }
 
 namespace vcpkg::Debug
diff --git a/toolsrc/src/vcpkg/install.cpp b/toolsrc/src/vcpkg/install.cpp
index 2874f39f49..3d6e4c2d93 100644
--- a/toolsrc/src/vcpkg/install.cpp
+++ b/toolsrc/src/vcpkg/install.cpp
@@ -699,15 +699,49 @@ namespace vcpkg::Install
         std::string specs_string;
         for (auto&& remove_action : action_plan.remove_actions)
         {
-            if (!specs_string.empty()) specs_string += ",";
+            if (!specs_string.empty()) specs_string.push_back(',');
             specs_string += "R$" + Hash::get_string_hash(remove_action.spec.to_string(), Hash::Algorithm::Sha256);
         }
+
         for (auto&& install_action : action_plan.install_actions)
         {
-            if (!specs_string.empty()) specs_string += ",";
+            if (!specs_string.empty()) specs_string.push_back(',');
             specs_string += Hash::get_string_hash(install_action.spec.to_string(), Hash::Algorithm::Sha256);
         }
 
+#if defined(_WIN32)
+        const auto maybe_common_triplet = common_projection(
+            action_plan.install_actions, [](const InstallPlanAction& to_install) { return to_install.spec.triplet(); });
+        if (maybe_common_triplet)
+        {
+            const auto& common_triplet = maybe_common_triplet.value_or_exit(VCPKG_LINE_INFO);
+            const auto maybe_common_arch = common_triplet.guess_architecture();
+            if (maybe_common_arch)
+            {
+                const auto maybe_vs_prompt = System::guess_visual_studio_prompt_target_architecture();
+                if (maybe_vs_prompt)
+                {
+                    const auto common_arch = maybe_common_arch.value_or_exit(VCPKG_LINE_INFO);
+                    const auto vs_prompt = maybe_vs_prompt.value_or_exit(VCPKG_LINE_INFO);
+                    if (common_arch != vs_prompt)
+                    {
+                        const auto vs_prompt_view = to_zstring_view(vs_prompt);
+                        System::print2(vcpkg::System::Color::warning,
+                                        "warning: vcpkg appears to be in a Visual Studio prompt targeting ",
+                                       vs_prompt_view,
+                                       " but is installing packages for ",
+                                       common_triplet.to_string(),
+                                       ". Consider using --triplet ",
+                                       vs_prompt_view,
+                                       "-windows or --triplet ",
+                                       vs_prompt_view,
+                                       "-uwp.\n");
+                    }
+                }
+            }
+        }
+#endif // defined(_WIN32)
+
         Metrics::g_metrics.lock()->track_property("installplan_1", specs_string);
 
         Dependencies::print_plan(action_plan, is_recursive, paths.ports);
diff --git a/toolsrc/src/vcpkg/triplet.cpp b/toolsrc/src/vcpkg/triplet.cpp
index 4bc684d0b6..8026baa8a8 100644
--- a/toolsrc/src/vcpkg/triplet.cpp
+++ b/toolsrc/src/vcpkg/triplet.cpp
@@ -32,12 +32,12 @@ namespace vcpkg
 
     const Triplet Triplet::X86_WINDOWS = from_canonical_name("x86-windows");
     const Triplet Triplet::X64_WINDOWS = from_canonical_name("x64-windows");
+    const Triplet Triplet::ARM_WINDOWS = from_canonical_name("arm-windows");
+    const Triplet Triplet::ARM64_WINDOWS = from_canonical_name("arm64-windows");
     const Triplet Triplet::X86_UWP = from_canonical_name("x86-uwp");
     const Triplet Triplet::X64_UWP = from_canonical_name("x64-uwp");
     const Triplet Triplet::ARM_UWP = from_canonical_name("arm-uwp");
     const Triplet Triplet::ARM64_UWP = from_canonical_name("arm64-uwp");
-    const Triplet Triplet::ARM_WINDOWS = from_canonical_name("arm-windows");
-    const Triplet Triplet::ARM64_WINDOWS = from_canonical_name("arm64-windows");
 
     Triplet Triplet::from_canonical_name(std::string&& triplet_as_string)
     {
@@ -51,4 +51,27 @@ namespace vcpkg
     const std::string& Triplet::to_string() const { return this->canonical_name(); }
     void Triplet::to_string(std::string& out) const { out.append(this->canonical_name()); }
     size_t Triplet::hash_code() const { return m_instance->hash; }
+
+    Optional<System::CPUArchitecture> Triplet::guess_architecture() const noexcept
+    {
+        using System::CPUArchitecture;
+        if (*this == X86_WINDOWS || *this == X86_UWP)
+        {
+            return CPUArchitecture::X86;
+        }
+        else if (*this == X64_WINDOWS || *this == X64_UWP)
+        {
+            return CPUArchitecture::X64;
+        }
+        else if (*this == ARM_WINDOWS || *this == ARM_UWP)
+        {
+            return CPUArchitecture::ARM;
+        }
+        else if (*this == ARM64_WINDOWS || *this == ARM64_UWP)
+        {
+            return CPUArchitecture::ARM64;
+        }
+
+        return nullopt;
+    }
 }