diff --git a/runtime/runtime-core/api/runtime-core.api b/runtime/runtime-core/api/runtime-core.api
index 0e8f85de3a..e488735251 100644
--- a/runtime/runtime-core/api/runtime-core.api
+++ b/runtime/runtime-core/api/runtime-core.api
@@ -1097,6 +1097,7 @@ public abstract interface class aws/smithy/kotlin/runtime/io/SdkSource : java/io
 
 public final class aws/smithy/kotlin/runtime/io/SdkSourceKt {
 	public static final fun readFully (Laws/smithy/kotlin/runtime/io/SdkSource;Laws/smithy/kotlin/runtime/io/SdkBuffer;J)V
+	public static final fun readRemaining (Laws/smithy/kotlin/runtime/io/SdkSource;Laws/smithy/kotlin/runtime/io/SdkBuffer;)J
 	public static final fun readToByteArray (Laws/smithy/kotlin/runtime/io/SdkSource;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public static final fun toSdkByteReadChannel (Laws/smithy/kotlin/runtime/io/SdkSource;Lkotlinx/coroutines/CoroutineScope;)Laws/smithy/kotlin/runtime/io/SdkByteReadChannel;
 	public static synthetic fun toSdkByteReadChannel$default (Laws/smithy/kotlin/runtime/io/SdkSource;Lkotlinx/coroutines/CoroutineScope;ILjava/lang/Object;)Laws/smithy/kotlin/runtime/io/SdkByteReadChannel;
diff --git a/runtime/runtime-core/common/src/aws/smithy/kotlin/runtime/io/SdkSource.kt b/runtime/runtime-core/common/src/aws/smithy/kotlin/runtime/io/SdkSource.kt
index aefb75dc08..4aa8e9fc4c 100644
--- a/runtime/runtime-core/common/src/aws/smithy/kotlin/runtime/io/SdkSource.kt
+++ b/runtime/runtime-core/common/src/aws/smithy/kotlin/runtime/io/SdkSource.kt
@@ -110,3 +110,23 @@ public fun SdkSource.readFully(sink: SdkBuffer, byteCount: Long) {
         totalBytesRead += rc
     }
 }
+
+/**
+ * **Caution** Reads the entire contents of the source into [sink].
+ * This function will read until the source is exhausted and no bytes remain
+ *
+ * @param sink the buffer that data read from the source will be appended to
+ */
+@InternalApi
+public fun SdkSource.readRemaining(sink: SdkBuffer): Long {
+    var totalReadBytes: Long = 0
+    var readBytes: Long
+
+    do {
+        // ensure any errors are propagated by attempting to read at least once
+        readBytes = read(sink, Long.MAX_VALUE)
+        totalReadBytes += readBytes
+    } while (readBytes != -1L)
+
+    return totalReadBytes + 1L // Account for last -1 read
+}