diff --git a/src/compiler/irgen.js b/src/compiler/irgen.js
index 39707ef5c6c..cb6f2a17226 100644
--- a/src/compiler/irgen.js
+++ b/src/compiler/irgen.js
@@ -664,7 +664,7 @@ class ScriptTreeGenerator {
                 const blockInfo = this.getBlockInfo(block.opcode);
                 if (blockInfo) {
                     const type = blockInfo.info.blockType;
-                    if (type === BlockType.REPORTER || type === BlockType.BOOLEAN) {
+                    if (type === BlockType.REPORTER || type === BlockType.BOOLEAN || type === BlockType.INLINE) {
                         return this.descendCompatLayer(block);
                     }
                 }
@@ -1416,7 +1416,7 @@ class ScriptTreeGenerator {
         const blockInfo = this.getBlockInfo(block.opcode);
         const blockType = (blockInfo && blockInfo.info && blockInfo.info.blockType) || BlockType.COMMAND;
         const substacks = {};
-        if (blockType === BlockType.CONDITIONAL || blockType === BlockType.LOOP) {
+        if (blockType === BlockType.CONDITIONAL || blockType === BlockType.LOOP || blockType === BlockType.INLINE) {
             for (const inputName in block.inputs) {
                 if (!inputName.startsWith('SUBSTACK')) continue;
                 const branchNum = inputName === 'SUBSTACK' ? 1 : +inputName.substring('SUBSTACK'.length);
diff --git a/src/compiler/jsgen.js b/src/compiler/jsgen.js
index d3e7784d81f..4fec750b5ed 100644
--- a/src/compiler/jsgen.js
+++ b/src/compiler/jsgen.js
@@ -439,9 +439,29 @@ class JSGenerator {
             return new TypedInput(`p${node.index}`, TYPE_UNKNOWN);
 
         case 'compat':
+            if (node.blockType === BlockType.INLINE) {
+                const branchVariable = this.localVariables.next();
+                const returnVariable = this.localVariables.next();
+                let source = '(yield* (function*() {\n';
+                source += `let ${returnVariable} = undefined;\n`;
+                source += `const ${branchVariable} = createBranchInfo(false);\n`;
+                source += `${returnVariable} = (${this.generateCompatibilityLayerCall(node, false, branchVariable)});\n`;
+                source += `${branchVariable}.branch = globalState.blockUtility._startedBranch[0];\n`;
+                source += `switch (${branchVariable}.branch) {\n`;
+                for (const index in node.substacks) {
+                    source += `case ${+index}: {\n`;
+                    source += this.descendStackForSource(node.substacks[index], new Frame(false));
+                    source += `break;\n`;
+                    source += `}\n`; // close case
+                }
+                source += '}\n'; // close switch
+                source += `return ${returnVariable};\n`;
+                source += '})())'; // close function and yield
+                return new TypedInput(source, TYPE_UNKNOWN);
+            }
             // Compatibility layer inputs never use flags.
             return new TypedInput(`(${this.generateCompatibilityLayerCall(node, false)})`, TYPE_UNKNOWN);
-
+          
         case 'constant':
             return this.safeConstantInput(node.value);
 
@@ -768,7 +788,7 @@ class JSGenerator {
             const blockType = node.blockType;
             if (blockType === BlockType.COMMAND || blockType === BlockType.HAT) {
                 this.source += `${this.generateCompatibilityLayerCall(node, isLastInLoop)};\n`;
-            } else if (blockType === BlockType.CONDITIONAL || blockType === BlockType.LOOP) {
+            } else if (blockType === BlockType.CONDITIONAL || blockType === BlockType.LOOP || blockType === BlockType.INLINE) {
                 const branchVariable = this.localVariables.next();
                 this.source += `const ${branchVariable} = createBranchInfo(${blockType === BlockType.LOOP});\n`;
                 this.source += `while (${branchVariable}.branch = +(${this.generateCompatibilityLayerCall(node, false, branchVariable)})) {\n`;
@@ -1192,6 +1212,16 @@ class JSGenerator {
         this.variableInputs = {};
     }
 
+    descendStackForSource (nodes, frame) {
+        // Wrapper for descendStack to get the source
+        const oldSource = this.source;
+        this.source = '';
+        this.descendStack(nodes, frame);
+        const stackSource = this.source;
+        this.source = oldSource;
+        return stackSource;
+    }
+
     descendStack (nodes, frame) {
         // Entering a stack -- all bets are off.
         // TODO: allow if/else to inherit values
diff --git a/src/engine/runtime.js b/src/engine/runtime.js
index 169c880f7d7..520f966f49a 100644
--- a/src/engine/runtime.js
+++ b/src/engine/runtime.js
@@ -1427,6 +1427,12 @@ class Runtime extends EventEmitter {
                 blockJSON.nextStatement = null; // null = available connection; undefined = terminal
             }
             break;
+        case BlockType.INLINE:
+            blockJSON.output = null;
+            blockInfo.disableMonitor = true;
+            blockInfo.branchCount = blockInfo.branchCount || 1;
+            blockJSON.outputShape = ScratchBlocksConstants.OUTPUT_SHAPE_SQUARE;
+            break;
         }
 
         const blockText = Array.isArray(blockInfo.text) ? blockInfo.text : [blockInfo.text];
diff --git a/src/extension-support/block-type.js b/src/extension-support/block-type.js
index ecaf70754dc..4680ef4af10 100644
--- a/src/extension-support/block-type.js
+++ b/src/extension-support/block-type.js
@@ -54,7 +54,13 @@ const BlockType = {
     /**
      * Arbitrary scratch-blocks XML.
      */
-    XML: 'xml'
+    XML: 'xml',
+
+    /**
+     * Specialized reporter block that allows for the insertion and evaluation
+     * of a substack.
+     */
+    INLINE: 'inline'
 };
 
 module.exports = BlockType;