diff --git a/CMakeLists.txt b/CMakeLists.txt
index f6d1f71299f..93ea10b07b4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -417,6 +417,7 @@ append("-DOPAQUE_VTBLS" LDC_CXXFLAGS)
 append("\"-DLDC_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}\"" LDC_CXXFLAGS)
 append("-DLDC_LLVM_VER=${LDC_LLVM_VER}" LDC_CXXFLAGS)
 append("\"-DLDC_LIBDIR_SUFFIX=\\\"${LIB_SUFFIX}\\\"\"" LDC_CXXFLAGS)
+append("-DLDC_HOST_FE_VER=${D_COMPILER_FE_VERSION}" LDC_CXXFLAGS)
 
 if(GENERATE_OFFTI)
     append("-DGENERATE_OFFTI" LDC_CXXFLAGS)
diff --git a/cmake/Modules/FindDCompiler.cmake b/cmake/Modules/FindDCompiler.cmake
index 61c2277b520..8c19d841e1f 100644
--- a/cmake/Modules/FindDCompiler.cmake
+++ b/cmake/Modules/FindDCompiler.cmake
@@ -8,6 +8,7 @@
 #  D_COMPILER_FLAGS    - D compiler flags (could be passed in the DMD environment variable)
 #  D_COMPILER_ID       = {"DigitalMars", "LDMD", "LDC", "GDC"}
 #  D_COMPILER_VERSION_STRING - String containing the compiler version, e.g. "DMD64 D Compiler v2.070.2"
+#  D_COMPILER_FE_VERSION - compiler front-end version, e.g. "2070"
 #  D_COMPILER_DMD_COMPAT - true if the D compiler cmdline interface is compatible with DMD
 
 
@@ -64,6 +65,8 @@ if (D_COMPILER)
                     OUTPUT_VARIABLE D_COMPILER_VERSION_STRING
                     ERROR_VARIABLE D_COMPILER_VERSION_STRING
                     ERROR_QUIET)
+    string(REGEX MATCH " (D Compiler|based on DMD) v([0-9]+)\\.([0-9]+)" D_COMPILER_FE_VERSION "${D_COMPILER_VERSION_STRING}")
+    math(EXPR D_COMPILER_FE_VERSION ${CMAKE_MATCH_2}*1000+${CMAKE_MATCH_3}) # e.g., 2079
     string(REGEX MATCH "^[^\r\n:]*" D_COMPILER_VERSION_STRING "${D_COMPILER_VERSION_STRING}")
 endif()
 
@@ -71,6 +74,7 @@ endif()
 if (D_COMPILER_FOUND)
     message(STATUS "Found host D compiler ${D_COMPILER}, with default flags '${D_COMPILER_FLAGS}'")
     message(STATUS "Host D compiler version: ${D_COMPILER_VERSION_STRING}")
+    message(STATUS "Host D compiler front-end version: ${D_COMPILER_FE_VERSION}")
 else()
     message(FATAL_ERROR "No D compiler found! Try setting the 'D_COMPILER' variable or 'DMD' environment variable.")
 endif()
diff --git a/dmd/cppmangle.d b/dmd/cppmangle.d
index 85122773760..18d4f344f28 100644
--- a/dmd/cppmangle.d
+++ b/dmd/cppmangle.d
@@ -943,7 +943,7 @@ public:
         if (t.isImmutable() || t.isShared())
             return error(t);
 
-        /* __c_long and __c_ulong get special mangling
+        /* magic structs __c_(u)long(long) get special mangling
          */
         const id = t.sym.ident;
         //printf("struct id = '%s'\n", id.toChars());
@@ -951,6 +951,10 @@ public:
             return writeBasicType(t, 0, 'l');
         else if (id == Id.__c_ulong)
             return writeBasicType(t, 0, 'm');
+        else if (id == Id.__c_longlong)
+            return writeBasicType(t, 0, 'x');
+        else if (id == Id.__c_ulonglong)
+            return writeBasicType(t, 0, 'y');
 
         //printf("TypeStruct %s\n", t.toChars());
         doSymbol(t);
diff --git a/dmd/cppmanglewin.d b/dmd/cppmanglewin.d
index e411c8256a2..0f89872951b 100644
--- a/dmd/cppmanglewin.d
+++ b/dmd/cppmanglewin.d
@@ -374,16 +374,18 @@ public:
     override void visit(TypeStruct type)
     {
         const id = type.sym.ident;
-        char c;
+        string c;
         if (id == Id.__c_long_double)
-            c = 'O'; // VC++ long double
+            c = "O"; // VC++ long double
         else if (id == Id.__c_long)
-            c = 'J'; // VC++ long
+            c = "J"; // VC++ long
         else if (id == Id.__c_ulong)
-            c = 'K'; // VC++ unsigned long
-        else
-            c = 0;
-        if (c)
+            c = "K"; // VC++ unsigned long
+        else if (id == Id.__c_longlong)
+            c = "_J"; // VC++ long long
+        else if (id == Id.__c_ulonglong)
+            c = "_K"; // VC++ unsigned long long
+        if (c.length)
         {
             if (type.isImmutable() || type.isShared())
             {
@@ -396,7 +398,7 @@ public:
                     return;
             }
             mangleModifier(type);
-            buf.writeByte(c);
+            buf.writestring(c);
         }
         else
         {
@@ -1025,7 +1027,8 @@ private:
             if (rettype.ty == Tstruct || rettype.ty == Tenum)
             {
                 const id = rettype.toDsymbol(null).ident;
-                if (id != Id.__c_long_double && id != Id.__c_long && id != Id.__c_ulong)
+                if (id != Id.__c_long_double && id != Id.__c_long && id != Id.__c_ulong &&
+                    id != Id.__c_longlong && id != Id.__c_ulonglong)
                 {
                     tmp.buf.writeByte('?');
                     tmp.buf.writeByte('A');
diff --git a/dmd/id.d b/dmd/id.d
index b7d2d435a07..dd6f9dfd7e1 100644
--- a/dmd/id.d
+++ b/dmd/id.d
@@ -111,6 +111,8 @@ immutable Msgtable[] msgtable =
     { "gate", "__gate" },
     { "__c_long" },
     { "__c_ulong" },
+    { "__c_longlong" },
+    { "__c_ulonglong" },
     { "__c_long_double" },
     { "cpp_type_info_ptr", "__cpp_type_info_ptr" },
     { "_assert", "assert" },
diff --git a/dmd/id.h b/dmd/id.h
index 81d30105eb5..39ac12a3e70 100644
--- a/dmd/id.h
+++ b/dmd/id.h
@@ -31,6 +31,8 @@ struct Id
     static Identifier *offsetof;
     static Identifier *__c_long;
     static Identifier *__c_ulong;
+    static Identifier *__c_longlong;
+    static Identifier *__c_ulonglong;
     static Identifier *__c_long_double;
     static Identifier *__switch;
     static Identifier *crt_constructor;
diff --git a/dmd/mars.d b/dmd/mars.d
index 9166b94d9c3..2dc4306e667 100644
--- a/dmd/mars.d
+++ b/dmd/mars.d
@@ -551,7 +551,14 @@ extern (C++) int mars_mainBody(ref Strings files, ref Strings libmodules)
     Objc._init();
     builtin_init();
 
-  version (IN_LLVM) {} else
+  version (IN_LLVM)
+  {
+    // LDC prints binary/version/config before entering this function.
+    // DMD prints the predefined versions as part of addDefaultVersionIdentifiers().
+    // Let's do it here after initialization, as e.g. Objc.init() may add `D_ObjectiveC`.
+    printPredefinedVersions();
+  }
+  else
   {
     printPredefinedVersions();
 
@@ -1610,8 +1617,7 @@ void addDefaultVersionIdentifiers()
 
 } // !IN_LLVM
 
-// IN_LLVM replaced: `private` by `extern (C++)`
-extern (C++) void printPredefinedVersions()
+private void printPredefinedVersions()
 {
     if (global.params.verbose && global.versionids)
     {
diff --git a/dmd/mars.h b/dmd/mars.h
index 31fee5e86e9..b775a7ce1ca 100644
--- a/dmd/mars.h
+++ b/dmd/mars.h
@@ -102,7 +102,6 @@ void ensurePathToNameExists(Loc loc, const char *name);
 
 #if IN_LLVM
 int mars_mainBody(Strings &files, Strings &libmodules);
-void printPredefinedVersions();
 #endif
 
 const char *importHint(const char *s);
diff --git a/driver/main.cpp b/driver/main.cpp
index 2a9f0b74b65..10fa5fbcc65 100644
--- a/driver/main.cpp
+++ b/driver/main.cpp
@@ -1123,7 +1123,6 @@ int cppmain(int argc, char **argv) {
 
 void addDefaultVersionIdentifiers() {
   registerPredefinedVersions();
-  printPredefinedVersions();
 }
 
 void codegenModules(Modules &modules) {
diff --git a/gen/abi.cpp b/gen/abi.cpp
index c7735746047..62855c00dad 100644
--- a/gen/abi.cpp
+++ b/gen/abi.cpp
@@ -197,6 +197,7 @@ bool TargetABI::isMagicCppStruct(Type *t) {
 
   Identifier *id = static_cast<TypeStruct *>(t)->sym->ident;
   return (id == Id::__c_long) || (id == Id::__c_ulong) ||
+         (id == Id::__c_longlong) || (id == Id::__c_ulonglong) ||
          (id == Id::__c_long_double);
 }
 
diff --git a/gen/abi.h b/gen/abi.h
index 89ad1175c8b..5fa553d4290 100644
--- a/gen/abi.h
+++ b/gen/abi.h
@@ -181,8 +181,8 @@ struct TargetABI {
   /// * complex number
   static bool isAggregate(Type *t);
 
-  /// The frontend uses magic structs to express the variable-sized C types
-  /// ((unsigned) long, long double) for C++ mangling purposes.
+  /// The frontend uses magic structs to express some primitive C types
+  /// ((unsigned) long (long), long double) for C++ mangling purposes.
   static bool isMagicCppStruct(Type *t);
 
   /// Returns true if the D type is a Plain-Old-Datatype, optionally excluding
diff --git a/gen/target.cpp b/gen/target.cpp
index 6eec49d28b9..c1b5091d16f 100644
--- a/gen/target.cpp
+++ b/gen/target.cpp
@@ -39,13 +39,15 @@ void Target::_init() {
 
   cppExceptions = true;
 
-  c_longsize = global.params.is64bit ? 8 : 4;
+  c_longsize =
+      global.params.is64bit && !triple.isWindowsMSVCEnvironment() ? 8 : 4;
   c_long_doublesize = realsize;
   classinfosize = 0; // unused
   maxStaticDataSize = std::numeric_limits<unsigned long long>::max();
 
-  int64Mangle = triple.isOSDarwin() ? 'x' : 'l';
-  uint64Mangle = triple.isOSDarwin() ? 'y' : 'm';
+  // These C++ mangling characters are only used for 64-bit POSIX targets.
+  int64Mangle = 'l';  // C++ long
+  uint64Mangle = 'm'; // C++ unsigned long
 
   // {Float,Double,Real}Properties have been initialized with the D host
   // compiler's properties.
diff --git a/runtime/druntime b/runtime/druntime
index 3cca35e7457..b12b0142f31 160000
--- a/runtime/druntime
+++ b/runtime/druntime
@@ -1 +1 @@
-Subproject commit 3cca35e7457643e88ae285cfd9150a5634c5f50b
+Subproject commit b12b0142f312d81771395024daf87c2f11becaa6
diff --git a/tests/d2/dmd-testsuite b/tests/d2/dmd-testsuite
index 4f08cfc4e17..187c6313531 160000
--- a/tests/d2/dmd-testsuite
+++ b/tests/d2/dmd-testsuite
@@ -1 +1 @@
-Subproject commit 4f08cfc4e17bc0b2d5e56eb35c0a1f5de26674ee
+Subproject commit 187c631353192339e5dabf44655c303bb6b22af7