auto import from //depot/cupcake/@135843
diff --git a/core/combo/javac.mk b/core/combo/javac.mk
new file mode 100644
index 0000000..d4c04e7
--- /dev/null
+++ b/core/combo/javac.mk
@@ -0,0 +1,37 @@
+# Selects a Java compiler.
+#
+# Inputs:
+# CUSTOM_JAVA_COMPILER -- "eclipse", "openjdk". or nothing for the system
+# default
+#
+# Outputs:
+# COMMON_JAVAC -- Java compiler command with common arguments
+
+# Whatever compiler is on this system.
+ifeq ($(HOST_OS), windows)
+ COMMON_JAVAC := development/host/windows/prebuilt/javawrap.exe -J-Xmx256m \
+ -target 1.5 -Xmaxerrs 9999999
+else
+ COMMON_JAVAC := javac -J-Xmx512M -target 1.5 -Xmaxerrs 9999999
+endif
+
+# Eclipse.
+ifeq ($(CUSTOM_JAVA_COMPILER), eclipse)
+ COMMON_JAVAC := java -Xmx256m -jar prebuilt/common/ecj/ecj.jar -5 \
+ -maxProblems 9999999 -nowarn
+ $(info CUSTOM_JAVA_COMPILER=eclipse)
+endif
+
+# OpenJDK.
+ifeq ($(CUSTOM_JAVA_COMPILER), openjdk)
+ # We set the VM options (like -Xmx) in the javac script.
+ COMMON_JAVAC := prebuilt/common/openjdk/bin/javac -target 1.5 \
+ -Xmaxerrs 9999999
+ $(info CUSTOM_JAVA_COMPILER=openjdk)
+endif
+
+HOST_JAVAC ?= $(COMMON_JAVAC)
+TARGET_JAVAC ?= $(COMMON_JAVAC)
+
+#$(info HOST_JAVAC=$(HOST_JAVAC))
+#$(info TARGET_JAVAC=$(TARGET_JAVAC))