diff --git a/README.markdown b/README.markdown
index e17b218..e8ff8b3 100644
--- a/README.markdown
+++ b/README.markdown
@@ -422,6 +422,10 @@ The following Unix compiler cc/gcc options are understood by cccl:
  - **-dumpversion** Version of cl.exe based on info in copyright banner
  - **-g**[0-9] Converts to cl.exe's **/Zi**
  - **-O0** Converts to cl.exe's **/Ot** optimization option
+ - **-O2** and **-O3** Converts to cl.exe's **/O2** optimization option
+ - **-Ofast** Converts to cl.exe's **/O2** and **/fp:fast** optimization option
+ - **-Os** Converts to cl.exe's **/O1** optimization option
+ - **-Oz** Converts to cl.exe's **/Os** optimization option
  - **-L<i>path</i>** Converts to linker option **/LIBPATH:_path_**
  - **-l<i>library</i>** Converts to **lib_library_.lib** (except **-link**)
  - **-m386** Converts to cl.exe's **/G3**
diff --git a/cccl b/cccl
index e977449..4038046 100755
--- a/cccl
+++ b/cccl
@@ -175,6 +175,22 @@ EOF
         clopt+=("${slash}O2")
         ;;
 
+    -O3)
+        clopt+=("${slash}O2")
+        ;;
+
+    -Ofast)
+        clopt+=("${slash}O2" "${slash}fp:fast")
+        ;;
+
+    -Os)
+        clopt+=("${slash}O1")
+        ;;
+
+    -Oz)
+        clopt+=("${slash}Os")
+        ;;
+
     -L)
         shift
         path=`echo "$1"`
@@ -310,12 +326,7 @@ EOF
         #ignore aliasing
         ;;
 
-    -isystem)
-        shift
-        clopt+=("${slash}I$1")
-        ;;
-
-    -I)
+    -isystem | -I)
         shift
         clopt+=("${slash}I$1")
         ;;
@@ -351,7 +362,7 @@ EOF
         fi
         ;;
 
-    *.cc | *.cxx | *.C)
+    *.cc | *.cxx | *.C | *.c++)
         # C++ source file with non .cpp extension, make sure cl understand 
         # that it is C++
         clopt+=("${slash}Tp$1")